Map of Philosophy v0.10.0

Key ideas:

• Ma'at: Ma'at joined ideas of truth, justice, right conduct, and cosmic and social order. Egyptian moral instruction framed good action as sustaining that order.
• Personhood and Afterlife: Mortuary texts distinguish the ka, ba, and akh among several aspects of a person. In the judgment scene preserved in Spell 125 of the Book of the Dead, the deceased's heart is weighed against Ma'at.
• Wisdom Literature: The Instruction of Ptahhotep belongs to Egyptian wisdom or didactic literature. It offers practical instruction about speech, restraint, justice, and conduct; calling it philosophy without qualification would prejudge the wider debate over how to classify the corpus.

Key ideas:

• Mortality in Gilgamesh: After Enkidu's death, Gilgamesh seeks escape from death and fails to secure lasting immortality. The epic keeps mortality, loss, fame, and the limits of human life in view without reducing them to a single maxim.
• Suffering and Divine Justice: Works collected as Babylonian wisdom literature, including the Babylonian Theodicy, stage disputes about undeserved suffering and the justice or inscrutability of the gods.
• Cuneiform Knowledge: Scribal word lists, omen series, legal texts, and other learned compilations organized knowledge through the structures of cuneiform writing. Treating these practices as philosophical is a modern scholarly argument, not an uncontested ancient classification.

Key ideas:

• Inquiry into Nature: The Milesians sought explanations in the world's own principles and processes while investigating celestial and terrestrial phenomena. This was not a simple one-step replacement of myth by reason, and their philosophical and scientific concerns were not separate disciplines.
• Originating Principles: Aristotle's later reconstruction presents water, the apeiron, and air as originating principles. Whether the Milesians also treated each as one material substance persisting through every change is disputed.
• Anaximander's Apeiron: Testimony describes the apeiron as an indefinite or boundless originating nature from which worlds and opposed qualities arise. Its exact character remains a matter of interpretation, and the fragmentary evidence cannot support claims of conceptual priority.

Influenced by:

• Mesopotamian Thought — Babylonian astronomical records and cosmogonical myth reached the Ionian coast, and the eclipse prediction that fixes Thales's acme is usually explained by access to them, though the method he used is unknown. — Uncertain: How much passed from Babylonia to Ionia is debated, and the parallels may reflect a shared Near Eastern milieu rather than direct borrowing.
• Egyptian Thought — Egyptian land measurement, redone after each inundation of the Nile, is the practical geometry that ancient sources say Thales met in Egypt and brought back to Greece. — Uncertain: The ancient reports that Thales studied in Egypt are later than the events and partly legendary, so what actually passed from Egyptian practice into Greek inquiry is contested.

Responds to:

• How Many Fundamental Substances? — Thales, Anaximander, and Anaximenes each proposed one originating stuff, water, the boundless, or air, from which everything else arises. Aristotle read these as the earliest answers, each naming one basic substance, though whether the Milesians held that stuff to persist through every change is disputed.

Key ideas:

• Brahman and Atman: The Upanishads relate Brahman (the ultimate, infinite reality) to Atman (the individual self) in sayings such as 'Tat tvam asi' (Thou art that); later interpreters disagreed over whether this means strict identity.
• Karma and Samsara: Actions (karma) generate consequences that bind the soul to the cycle of death and rebirth (samsara). The Upanishads teach that liberation (moksha) comes through knowledge; paths of devotion and disciplined action were added by later texts.
• Nasadiya Sukta: The famous 'Creation Hymn' of the Rig Veda (10.129) questions the very possibility of knowing the origin of existence — a remarkably skeptical and open-ended inquiry for its time.

Key ideas:

• Asha and Druj: The early hymns contrast truth and right order with falsehood and call people to align their thought, speech, and action with Asha.
• Moral Choice: Human choices carry consequences for the person and participate in the wider struggle between good and evil.
• Developed Cosmic Dualism: Later sources give a fuller cosmology of conflict between Ohrmazd and Ahriman than the early hymns alone provide.
• Judgment and Final Renovation: Zoroastrian eschatology developed accounts of judgment after death, resurrection, and a final restored world in which evil no longer causes harm.

Key ideas:

• Against the Stoic Criterion: Academic arguments deny that any sense-impression carries the self-guaranteeing mark of truth claimed by the Stoics. On a dialectical reading, these arguments expose consequences of Stoic premises without stating the Academics' own doctrine.
• Persuasive Impressions: Carneades distinguished grades of persuasiveness and described how a person could examine and act on the strongest impressions. Whether this was his own doctrine or a dialectical reply to the Stoics is disputed.
• Academic Dialectic: The Academics used Academic Dialectic, arguing on both sides and from opponents' premises, to test positions without thereby adopting the resulting conclusions.

Influenced by:

• Platonism — Arcesilaus claimed as his model Socrates' practice in Plato's dialogues, which refutes a claim to knowledge using only premises the claimant accepts, and Cicero's history has him following Socrates and Plato in concluding that nothing can be known.

Reacts to:

• Stoicism

Holds:

• Academic Fallibilism — Question scope: The Possibility of Knowledge — Carneades developed the persuasive-impression criterion in reply to Stoic objections that skepticism made action impossible. Whether he endorsed it as his own doctrine or advanced it dialectically remains disputed.

Key ideas:

• Atoms and Void: Reality consists entirely of an infinite number of indivisible, eternal particles (atoms) differing only in shape, size, and arrangement, moving through empty space.
• Mechanical Causation: Everything occurs by necessity through the collision and combination of atoms. There is no teleology or design — only matter in motion.
• Cheerfulness (Euthymia): Democritus held that the goal of life is tranquility of mind, achieved through moderation and an understanding of the natural world.

Influenced by:

• Eleaticism
• Pluralists — Extended the pluralist response to Parmenides — Empedocles' roots and Anaxagoras' seeds — replacing qualitatively distinct principles with uniform atoms moving in the void.

Responds to:

• How Many Fundamental Substances? — As Aristotle reports them, Leucippus and Democritus answered with infinitely many substances of one kind: indivisible atoms of a single uniform stuff, differing only in shape, arrangement and position. Beside them is the void, which they called 'what is not' yet held to be no less real than what is. Everything else is the atoms' arrangement.

Key ideas:

• Four Noble Truths: Life involves suffering (dukkha); suffering arises from craving (tanha); suffering can cease; the path to cessation is the Noble Eightfold Path.
• Anatta (No-Self): There is no permanent, unchanging self or soul. What we call 'self' is a constantly changing stream of physical and mental processes (the five aggregates).
• Dependent Origination: Conditioned phenomena arise and cease in dependence on specific causes and conditions. Applied to suffering, this teaching explains both its continuation and the possibility of its cessation.

Reacts to:

• Vedic Philosophy — Rejected the authority and efficacy of Vedic sacrificial ritual and the Brahminical order, replacing them with a path of insight open to all.
• Jainism

Holds:

• Dependent Origination — Question scope: The Origin and Cessation of Suffering
• No-Self — Question scope: Existence of the Self

Key ideas:

• Ren (Benevolence): A central Confucian virtue encompassing humaneness and care for others, cultivated through conduct such as reciprocity.
• Li 禮 (Ritual Propriety): The network of social rituals, customs, and norms that structure harmonious human relationships — from family life to statecraft.
• Self-Cultivation: Moral development is a lifelong process of study, reflection, and practice. The junzi (exemplary person) leads by moral example, not coercion.

Holds:

• Virtue Ethics — Question scope: The Basis of Right Action

Key ideas:

• Life According to Nature: Happiness comes from living in harmony with nature, stripping away the artificial needs created by society — wealth, reputation, comfort are chains, not goods.
• Askesis: Rigorous self-discipline and voluntary hardship strengthen the soul. The Cynic trains to need nothing and fear nothing.
• Cosmopolitanism: Diogenes declared himself a 'citizen of the world' (kosmopolites), rejecting the boundaries of city-states — one of the earliest expressions of universal human kinship.

Responds to:

• The Basis of Right Action — The Cynics answered that virtue is sufficient for happiness and consists in living according to nature, in self-sufficiency and the disregard of convention; they taught it by example and by shocking practice rather than as a theory, so no named position is attributed.

Key ideas:

• The Way of Truth: Parmenides argued that 'what is' must be eternal, unchanging, and one — for nothing can come from nothing, and being cannot become non-being.
• Zeno's Paradoxes: Zeno crafted ingenious arguments showing that our common-sense notions of motion, space, and plurality lead to contradictions, defending Parmenides' monism.
• Reason vs. Senses: The Eleatics established a fundamental distinction between the deliverances of reason (truth) and the appearances given by the senses (opinion).

Influenced by:

• Milesians
• Pythagoreanism

Holds:

• Eleatic Monism — Question scope: Permanence and Change

Key ideas:

• Ataraxia: The goal of life is tranquility — freedom from anxiety (ataraxia) and bodily pain (aponia). Simple pleasures, friendship, and philosophical contemplation are the path.
• Death is Nothing: "When we are, death is not come, and, when death is come, we are not" (Letter to Menoeceus 125, tr. Hicks). Since we cannot experience death, fearing it is irrational.
• Atomic Swerve: Atoms occasionally swerve unpredictably, introducing indeterminacy into the cosmos and grounding human free will against strict determinism.

Influenced by:

• Atomism — Epicurus took over Democritus' indivisible bodies moving in empty space, where shape, size and arrangement explain everything else. He then gave those atoms weight and an unpredictable swerve, so that motion would not run by the strict necessity Democritus accepted.

Holds:

• Physicalism — Question scope: The Mind–Body Problem — Epicurus held the soul to be a body of very fine atoms spread through the whole frame, which scatters when the body dies.
• Libertarian Free Will — Question scope: Free Will — The swerve is not in Epicurus's surviving writings; Lucretius and Cicero attribute it to him. — Uncertain: Scholars dispute what freedom the swerve was meant to secure: some read it as the ability to do otherwise, while others argue that it protects our control over how our character develops (Furley, Bobzien) or only keeps the future open (O'Keefe), which is not free will in the modern sense.

Key ideas:

• Universal Flux: All things are in perpetual change. The world is a process rather than a collection of fixed objects, and what looks like a stable thing is a pattern held steady within that change.
• Logos: A rational principle governing all change — the hidden harmony behind the apparent chaos. Most people fail to perceive it, living as if asleep.
• Unity of Opposites: Opposites are interdependent: 'The road up and the road down are one and the same.' Conflict and tension are not defects but the very structure of reality.

Influenced by:

• Milesians

Holds:

• Universal Flux — Question scope: Permanence and Change

Key ideas:

• Ahimsa: Non-violence is the supreme ethical principle. Jain monks sweep the path before them and strain water to avoid harming even the smallest creatures.
• Anekantavada: Reality is complex and many-sided; no single viewpoint captures the whole truth. This doctrine of non-absolutism encourages intellectual humility and tolerance.
• Karma as Substance: Uniquely, Jainism treats karma as fine material particles that cling to the soul, weighing it down. Ascetic practice burns off karmic matter, gradually liberating the soul.

Reacts to:

• Vedic Philosophy — A heterodox (nāstika) tradition that explicitly rejects Vedic authority while absorbing the shared Indian conceptual milieu of karma, moksha, and saṃsāra.

Key ideas:

• Rule by Law: Laws must be clear, public, and impartially enforced. The ruler governs through an impersonal legal system, not personal virtue or relationships.
• Self-Interest: Han Feizi argued that people act from self-interest, not benevolence. Effective governance aligns individual self-interest with the state's goals through rewards and punishments.
• The Two Handles: The ruler's essential tools are reward and punishment. Used consistently, they make the state a self-regulating mechanism that requires no moral exhortation.

Influenced by:

• Taoism — Han Feizi borrowed the Laozi's language of the Way and of the ruler's non-action for a ruler who stays empty and still, hides his preferences, and lets impersonal laws govern; the borrowing framed his statecraft without being fully assimilated into it.

Reacts to:

• Confucianism — Against Confucian moral cultivation, Han Feizi argued that relying on virtue to govern is naive and that only impersonal law can secure order.

Key ideas:

• Universal Love: Mozi argued that partiality — loving one's own family or state more than others — is the root of conflict. Impartial concern for all would create a harmonious world.
• Consequentialism: Actions and policies should be judged by their outcomes: do they benefit the people, enrich the state, and increase the population? This is a remarkably early form of utilitarian reasoning.
• Anti-Fatalism: Mozi rejected belief in fate (ming), arguing that human effort determines outcomes and that fatalism leads to moral laziness.

Reacts to:

• Confucianism — Mozi trained in the Confucian tradition but rejected its partiality, elaborate ritual, and fatalism in favor of impartial care and consequentialist reasoning.

Holds:

• Consequentialism — Question scope: The Basis of Right Action — Mohist consequentialism judges acts and policies by their benefit to the world, counted as wealth, population, and order, rather than by individual happiness.

Key ideas:

• Four Causes: To explain anything fully requires identifying its material, formal, efficient, and final causes — what it's made of, its structure, what produced it, and its purpose.
• Hylomorphism: Aristotle analyzes perceptible substances as compounds of matter (hyle) and form (morphe), locating their forms in the substances themselves.
• Eudaimonia and Virtue: The good life consists in flourishing (eudaimonia), achieved by developing virtues — stable dispositions to act in accordance with reason, hitting the mean between extremes.
• Formal Logic: Aristotle's logical works contain the earliest surviving formal study of logic. Their account of syllogistic deduction shaped later ancient, Arabic, and Latin logical traditions.

Influenced by:

• Platonism — Aristotle trained in Plato's Academy for about twenty years, and Platonic questions and methods remained a major point of departure even where his own school rejected Plato's answers.

Reacts to:

• Platonism — Aristotle's rejection of separately existing Forms — locating form in the particular substance rather than a transcendent realm — is his defining departure from his teacher.

Holds:

• Virtue Ethics — Question scope: The Basis of Right Action

Key ideas:

• Forms: Plato's middle dialogues distinguish intelligible Forms from the changing particulars that participate in them; later Platonists developed and disputed how this account should be understood.
• Allegory of the Cave: The Republic compares ordinary understanding to prisoners seeing shadows and philosophical education to an ascent toward the light of the Good.
• Tripartite Soul: The Republic distinguishes reason, spirit, and appetite, and links justice to their ordered relation.
• Anamnesis: The Meno and Phaedo present learning as recollection, connecting inquiry with the soul's prior knowledge.

Influenced by:

• Pythagoreanism

Reacts to:

• Sophism — Plato's dialogues argue sustainedly against Sophistic relativism and rhetoric, defending objective truth and the good against 'man is the measure'.

Synthesizes:

• Heracliteanism — Plato assigned Heraclitus's ceaseless flux to the world of the senses: because particulars never stay the same, they cannot be what knowledge is about.
• Eleaticism — Plato kept the Parmenidean demand that whatever truly is must be one, changeless and reached by reason rather than the senses, and made that the character of the Forms.

Holds:

• Platonic Realism — Question scope: The Problem of Universals
• Substance Dualism — Question scope: The Mind–Body Problem — The arguments are Plato's own, in the Phaedo, Meno and Phaedrus; later Platonist accounts of the soul descend from them.

Key ideas:

• Four Elements: Empedocles' earth, water, air, and fire are eternal and unchanging; all change is mixture and separation driven by the cosmic forces of Love (attraction) and Strife (repulsion).
• Nous (Mind): Anaxagoras introduced Mind as an ordering principle — infinite, self-ruling, and unmixed — that initiated cosmic rotation and continues to govern the arrangement of matter.

Influenced by:

• Milesians
• Eleaticism

Responds to:

• How Many Fundamental Substances? — Empedocles answered Parmenides with four permanent roots, earth, water, air, and fire, mixed and parted by Love and Strife, and Anaxagoras with unlimited seeds of every kind ordered by Mind: many basic substances, none of which comes to be or perishes.

Key ideas:

• Epoché: Suspension of judgment: when opposing arguments appear equally balanced, the Pyrrhonist neither affirms nor denies but suspends judgment on every non-evident matter, while still going along with how things appear.
• The Ten Modes: Aenesidemus cataloged ten types of disagreement (cultural, perceptual, circumstantial) that leave the arguments on either side of a question balanced, so that suspension of judgment follows. The modes induce suspension; they do not prove that knowledge is impossible, which would itself be a dogma.
• Ataraxia through Skepticism: Tranquility follows suspension of judgment as a shadow follows the body — when we stop insisting on dogmatic beliefs, anxiety dissolves.

Influenced by:

• Atomism — Drew on the Atomist emphasis on the unreliability of the senses; Pyrrho was a pupil of the Democritean Anaxarchus.

Reacts to:

• Stoicism — The engagement is that of the later Pyrrhonists: Aenesidemus and Sextus Empiricus argued against the Stoics as dogmatists who claim to have found the truth, setting against that claim the skeptic who is still investigating and suspends judgment.

Holds:

• Epistemic Skepticism
• Pyrrhonian Suspension — Question scope: The Possibility of Knowledge

Key ideas:

• Number and Order: Fifth-century Pythagoreans, especially Philolaus, developed accounts in which limiters, unlimiteds, harmony, and number make an ordered cosmos intelligible. These developed teachings should not be read back wholesale into Pythagoras.
• Music and Ratio: The tradition connected musical concords with whole-number ratios. The earliest secure evidence for demonstrating these relations belongs to later Pythagoreans, so the discovery cannot confidently be credited to Pythagoras himself.
• Transmigration and a Way of Life: Early testimony associates Pythagoras and his followers with transmigration of souls and a disciplined communal life. The surviving evidence does not establish a detailed theory of the soul or a complete program of spiritual purification taught by Pythagoras himself.

Responds to:

• How Many Fundamental Substances? — The fifth-century Pythagoreans, above all Philolaus, held that the world is fitted together from limiters and unlimiteds by a harmony, and that number is what makes anything knowable, so that ordered structure rather than any material stuff is what is basic.

Key ideas:

• Relativism: Protagoras declared 'man is the measure of all things' — truth and value are relative to the perceiver, not fixed by nature or the gods.
• Nomos vs. Physis: The Sophists debated whether justice, morality, and law (nomos) are natural or merely conventional — a question that remains central to political philosophy.
• Power of Rhetoric: Gorgias called speech 'a powerful lord' that works on the soul as a drug works on the body, persuading independently of what is true — which raises questions about the relationship between persuasion, truth, and power.

Reacts to:

• Eleaticism — Gorgias' On Not-Being turned rigorous Eleatic argument against Parmenides' conclusions — that nothing is, that if it is it cannot be known, and that if known it cannot be communicated.

Holds:

• Relativism
• Protagorean Relativism — Question scope: The Nature of Truth

Key ideas:

• Virtue as the Sole Good: External circumstances — wealth, health, reputation — are 'preferred indifferents.' Only virtue (wisdom, courage, justice, temperance) constitutes genuine good.
• Dichotomy of Control: Distinguish what is 'up to us' (our judgments, intentions) from what is not (events, others' actions). Freedom and tranquility come from focusing only on what we can control.
• Logos and Providence: The universe is governed by a rational principle (Logos). Everything that happens is part of a rational, deterministic order — the wise person embraces this with willing acceptance of fate.
• Cosmopolitanism: All humans share in the universal Logos and are fellow citizens of the cosmos. Stoic ethics extends naturally to universal human dignity and brotherhood.

Influenced by:

• Heracliteanism
• Platonism
• Cynicism

Reacts to:

• Epicureanism — The two schools competed directly on ethics (virtue versus pleasure) and physics (a providential logos versus the random swerve of atoms).

Holds:

• Virtue Ethics — Question scope: The Basis of Right Action
• Suffering as False Judgment — Question scope: The Origin and Cessation of Suffering
• Compatibilism — Question scope: Free Will — Chrysippus held that every action is fated, yet our assent to what appears to us is up to us, so we are rightly held responsible even though we could not have done otherwise.

Key ideas:

• Dao: The Daodejing uses the Way to discuss how the world unfolds and how guidance can resist capture by fixed names.
• Wu Wei: Non-coercive or effortless action avoids forcing outcomes and allows conduct to respond to how situations develop.
• Zhuangzi's Shifting Perspectives: The Zhuangzi uses humor, paradox, and changing viewpoints to unsettle rigid distinctions and claims to uniquely authoritative guidance.
• Later Religious Traditions: Daoist communities developed ritual, revelation, bodily cultivation, and institutional lineages while continually reinterpreting the early texts.

Reacts to:

• Confucianism

Responds to:

• The Meaning of Life — Early Daoist texts approach a good life through wu-wei (non-coercive action) and ziran (naturalness), questioning fixed social values and imposed standards rather than supplying one final purpose for every life.

Key ideas:

• Pali Canon: The Tipitaka ('Three Baskets') — the oldest complete Buddhist scripture, comprising the Buddha's discourses (Suttas), monastic rules (Vinaya), and systematic philosophy (Abhidhamma).
• Abhidhamma Analysis: A minute analysis of experience into ultimate constituents (dhammas) — momentary mental and physical events that arise and pass away in rapid succession.
• Vipassana: Insight meditation: the systematic observation of body and mind to directly see impermanence, suffering, and non-self — leading to liberation.

Influenced by:

• Buddhism — Carries forward the Buddha's own teaching as its doctrinal core: the four noble truths, the eightfold path, dependent origination, and no-self.

Holds:

• No-Self — Question scope: Existence of the Self — Theravada Abhidhamma explains how one life continues without an enduring self through the life-continuum mind (bhavanga), itself a series of separate mental moments.

Key ideas:

• Purusha and Prakriti: Classical Samkhya distinguishes many eternal purushas (pure, inactive consciousnesses) from a single eternal prakriti (active, unconscious nature). Their conjunction accounts for experience and the evolution of the manifest world.
• Three Gunas: All of material nature is composed of three qualities (gunas): sattva (light, goodness), rajas (activity, passion), and tamas (darkness, inertia). Their interplay drives all change.
• Discriminative Knowledge: Liberation (kaivalya) occurs when purusha recognizes its complete distinction from prakriti — 'I am not this body, these thoughts, these emotions.'

Influenced by:

• Vedic Philosophy — Took from the Vedas and Upanishads the term puruṣa for the conscious self, together with the framework in which action binds one to rebirth and knowledge wins release.

Responds to:

• Existence of the Self — Sāṃkhya answers with a plurality of eternal conscious selves, the puruṣas, each distinct from the mind and body that unconscious prakṛti evolves: the self exists, but as a witness, not as the thinking and feeling person.

Key ideas:

• Emptiness of Emptiness: Nagarjuna insists that emptiness itself is not a thing or a substance — it is simply the absence of inherent existence. Even emptiness is empty.
• Two Truths: Conventional truth (samvriti-satya) operates at the everyday level; ultimate truth (paramartha-satya) reveals the emptiness of all things. Both are necessary; neither is discarded.
• Tetralemma: Nagarjuna systematically negates four possible positions on any claim: it is, it is not, it both is and is not, it neither is nor is not — dissolving all conceptual fixation.

Influenced by:

• Mahayana

Key ideas:

• Bodhisattva Ideal: Rather than seeking liberation for oneself alone, the bodhisattva vows to attain full awakening for the sake of all beings, and treats compassion as the supreme virtue.
• Sunyata (Emptiness): All phenomena are empty of inherent, independent existence. Emptiness is not nothingness but the absence of fixed essence — everything exists dependently.
• Skillful Means (Upaya): The Buddha adapts his teaching to the capacities of each listener. Different doctrines and practices are appropriate for different people at different stages.

Influenced by:

• Buddhism — Mahayana was not a separate ordination lineage: its followers kept the same monastic rule and the same teaching of no-self and dependent origination as other Buddhists, and pushed that teaching further, from the absence of a self in the person to the emptiness of every thing.

Holds:

• No-Self — Question scope: Existence of the Self — Nagarjuna's Madhyamaka denies the self as one case of emptiness: like every other phenomenon, the self lacks an inherent nature of its own.

Key ideas:

• The One: The ultimate principle beyond being and thought — absolutely simple, infinite, and the source from which all reality emanates, as light radiates from the sun.
• Emanation: Reality flows outward from the One in a necessary, eternal process: One → Nous (Intellect) → World Soul → Nature → Matter, each level less perfect than its source.
• Contemplative Return: The soul can ascend back through the levels of reality via philosophical contemplation and purification, ultimately achieving mystical union with the One.

Influenced by:

• Stoicism
• Pythagoreanism — Iamblichus placed Limit and the Unlimited, the paired principles of Philolaus's Pythagoreanism, at the top of his system just below the One, and treated mathematics practised in a Pythagorean manner as a purifying ascent of the soul.

Synthesizes:

• Platonism — Plotinus read the Good beyond being of the Republic and the first hypothesis of the Parmenides as one and the same first principle, and placed Plato's Forms inside Intellect rather than in a realm of their own.
• Peripatetic School — Plotinus made Aristotle's self-thinking divine intellect the model for Nous, the second level of reality, and used the matter-and-form analysis throughout, while denying that the first principle could be an intellect at all.

Responds to:

• The Existence of God — Plotinus answers with the One: an ineffable first principle beyond being and intellect, the source from which all reality emanates and to which the soul ascends — the divine understood as absolute unity rather than a being among beings.

Key ideas:

• Faith Seeking Understanding: Augustine established the model: faith precedes but does not exclude reason. Philosophy serves theology, and the tools of Greek thought illuminate Christian doctrine.
• The Problem of Evil: Evil is not a positive substance but a privation of good (privatio boni). God permits evil because free will — which makes genuine love possible — also makes sin possible.
• Divine Illumination: Just as the sun enables sight, God illuminates the mind to grasp eternal truths. Human knowledge ultimately depends on divine light.

Influenced by:

• Neoplatonism — The engagement is that of the later Fathers, Augustine above all: Confessions VII.9 records that the books of the Platonists, read in Latin translation, taught him to conceive God as incorporeal and gave him the eternal Word, though not the Incarnation.
• Stoicism
• Zoroastrianism — Zoroastrian eschatology, cosmic dualism, and angelology may have shaped early Christian thought through centuries of Persian–Jewish contact. — Uncertain: The extent of direct Zoroastrian influence is contested; the parallels may reflect a shared Near Eastern milieu rather than borrowing.

Holds:

• Theism — Question scope: The Existence of God

Key ideas:

• Chitta Vritti Nirodha: Yoga is the stilling of mental fluctuations. When the mind ceases its restless activity, pure consciousness (purusha) is revealed in its own nature.
• Eight Limbs (Ashtanga): The path proceeds through: ethical restraints, observances, posture, breath control, sense withdrawal, concentration, meditation, and finally samadhi (absorption).
• Samadhi: The highest state of consciousness — complete absorption in which the distinction between knower, known, and knowing dissolves, revealing the true Self.

Influenced by:

• Vedic Philosophy
• Classical Samkhya — Vyāsa's commentary on the Yoga Sūtras draws on the Sāṃkhya teachers whose system Īśvarakṛṣṇa's Kārikā summarizes, which is the school's documented contact with the classical school; the dualism of puruṣa and prakṛti that Patanjali's sūtras already presuppose belongs to the older Sāṃkhya current that predates it.

Key ideas:

• Consciousness-Only: In the strands that defend this teaching, sensible objects are known as appearances within cognition and experiences arise through mental causes. Whether this denies a mind-independent reality or instead limits what can be claimed about it remains disputed.
• Alaya-Vijnana: The storehouse consciousness underlies all experience, containing 'seeds' (bija) deposited by past actions that ripen into future perceptions and experiences.
• Three Natures: This teaching distinguishes the imagined nature of false projections, the dependent nature of causally conditioned experience, and the perfected nature disclosed when the imagined is absent from the dependent.

Influenced by:

• Mahayana

Key ideas:

• Advaita (Non-Dualism): Śaṅkara's radical teaching: the distinction between self and Brahman is caused by ignorance (avidya). In truth, there is only one reality — Brahman — and 'you are that.'
• Maya: The world of multiplicity is not ultimately real but a superimposition (adhyasa) of ignorance upon Brahman — like mistaking a rope for a snake.
• Three Levels of Reality: Advaita distinguishes paramarthika (absolute reality — Brahman), vyavaharika (empirical reality — the everyday world), and pratibhasika (illusory — dreams, mirages).

Influenced by:

• Vedic Philosophy — Treats the Upaniṣadic sentences as the only means of knowing brahman, which reasoning alone cannot reach; Śaṅkara's argument accordingly turns on reading identity statements such as 'that thou art'.

Reacts to:

• Buddhism
• Classical Samkhya — Śaṅkara's Brahma-Sūtra commentary rejects Sāṃkhya's claim that unconscious prakṛti could produce an ordered cosmos, arguing that only conscious Brahman can be its source.

Responds to:

• Existence of the Self — Against no-self views, Vedānta affirms a real, enduring self (ātman) established by the Upaniṣads; its schools then differ on the self's relation to brahman — strict identity in Advaita, distinct-yet-dependent in Viśiṣṭādvaita and Dvaita.

Key ideas:

• Direct Pointing: 'A special transmission outside the scriptures; not depending on words and letters; pointing directly at the mind; seeing into one's nature and attaining Buddhahood.'
• Koan Practice: Recorded cases like 'What is the sound of one hand clapping?' are held until ordinary explanation is exhausted and the student can answer from insight (satori) rather than from reasoning.
• Everyday Mind: Enlightenment is not otherworldly but found in ordinary activities — chopping wood, carrying water. The sacred is not separate from the mundane.

Influenced by:

• Taoism — Chinese Chan fitted Buddhism's denial of the ego into the practical naturalism of the Laozi and Zhuangzi, and shared the Zhuangzi's ideal of losing oneself in a perfected everyday skill.
• Mahayana
• Madhyamaka — Chan received Madhyamaka through its Chinese transmission: Sengzhao, Kumārajīva's pupil and the chief transmitter of Madhyamaka teaching in China, wrote on emptiness in a paradoxical style that made him a favorite of the later Chan school, which counted him among its unofficial patriarchs.

Holds:

• No-Self — Question scope: Existence of the Self — Zen seeks direct, non-conceptual realization of no-self: 'to study the self is to forget the self' — in zazen the boundary between subject and object drops away, disclosing the emptiness of any fixed, separate self.

Key ideas:

• Autonomy of Philosophy: Latin Averroists held that philosophy has its own domain and methods, independent of theology. Where they overlap, both pursue truth — contradiction between them is only apparent.
• Unity of the Intellect: On the Latin Averroist reading of Aristotle, the material (or possible) intellect is single, separate, and shared by all humans. Scholars dispute exactly what this account entails for personal immortality; it puts ordinary individual survival under pressure, but the consequence is not settled.
• Eternity of the World: Latin Averroists held that the world has no temporal beginning — it is eternal, sustained in existence by God as its eternal cause.

Influenced by:

• Medieval Islamic Philosophy — Siger of Brabant and other Paris arts masters read Aristotle with Ibn Rushd's commentaries, in Latin from about 1230, and took from them his thesis that there is one intellect for all human beings; Siger also took his view that human happiness lies in conjunction with the active intellect.
• Peripatetic School — Siger of Brabant and Boethius of Dacia developed Aristotle's philosophy on its own terms even where it contradicted Christian teaching; Boethius held that Aristotelian natural science must deny that the world had a beginning.

Key ideas:

• Sefirot (Divine Emanations): Ten luminous attributes through which the infinite Godhead (Ein Sof) manifests itself, forming a dynamic structure that mediates between divine transcendence and the created world.
• Tsimtsum (Divine Contraction): Isaac Luria's concept that creation required God's voluntary withdrawal, making space for a finite world — a radical inversion of emanation as expansion.
• Tikkun (Repair of the World): The redemptive task of gathering scattered sparks of divine light through ethical and spiritual practice, restoring wholeness to a fractured cosmos.

Influenced by:

• Neoplatonism — Absorbed Neoplatonic emanation theology through Islamic and Jewish intermediaries: the sefirot echo Plotinus's hypostases, though Kabbalah, unlike Neoplatonism, gives the divine life a personal and morally charged character.
• Medieval Jewish Philosophy
• Sufism — Sufi mystical practice and theosophical vocabulary reached Jewish mystical writing through contact with the Islamicate world. — Uncertain: The route by which Sufi practice reached Jewish mystical writing is debated.

Key ideas:

• Essence and Existence: Avicenna's groundbreaking distinction: in all beings except God, essence (what a thing is) is distinct from existence (that it is). Only in God are essence and existence identical.
• Philosophy and Revelation: Islamic philosophers debated whether philosophical reason and Quranic revelation are compatible. Averroes argued they are two paths to the same truth; Al-Ghazali defended revelation's supremacy.
• Emanation: Al-Farabi and Avicenna described creation as an eternal emanation from God through successive intellects — reconciling Greek cosmology with Islamic theology.

Influenced by:

• Peripatetic School — Once the whole of Aristotle's corpus had been translated into Arabic, al-Farabi and Avicenna read it as one system of demonstrative science crowned by the Metaphysics, and Alexander of Aphrodisias's treatises shaped their cosmology and their account of the intellect.
• Neoplatonism — Arabic versions of Plotinus and Proclus, circulating under Aristotle's name as the Theology of Aristotle and the Book on the Pure Good, gave falsafa the hierarchy of One, Intellect, and Soul, and al-Farabi built on it his account of the world arising from the First by necessary, eternal emanation.

Holds:

• Theism — Question scope: The Existence of God

Key ideas:

• Reason and Revelation: Medieval Jewish philosophers disputed how far philosophical demonstration could interpret scripture and religious law. Maimonides defended their compatibility when each was properly understood, while other thinkers placed different limits on reason's authority.
• Language about God: Maimonides's negative theology held that positive descriptions cannot state God's essence; his account was one influential contribution to a wider medieval debate about divine attributes.
• Prophecy, Providence, and Law: The tradition used philosophical arguments to examine prophecy, divine knowledge and care, human freedom, and the relationship between divine and human law.

Influenced by:

• Medieval Islamic Philosophy
• Peripatetic School — Maimonides used Aristotelian logic and metaphysics to reinterpret Scripture, reconciling revelation with demonstrative reason in the Guide of the Perplexed.

Holds:

• Theism — Question scope: The Existence of God

Key ideas:

• Via Negativa: God transcends all human concepts. We approach the divine not by affirming attributes but by denying that any of our concepts adequately applies to God, entering the 'divine darkness.'
• Gelassenheit (Releasement): Eckhart's key concept: letting go of self-will, attachments, and even the desire for God — creating an inner emptiness in which the divine can be born in the soul.
• Unio Mystica: The ultimate goal: mystical union with God in which the distinction between the soul and the divine dissolves — 'The eye with which I see God is the same eye with which God sees me.'

Influenced by:

• Neoplatonism
• Patristics
• Sufism — Direct borrowing is documented for Ramon Llull, who wrote that his Book of the Lover and the Beloved followed the manner of the Sufis. — Uncertain: Wider claims of Sufi influence on Christian mystics such as John of the Cross go back to Asín Palacios and remain debated.

Holds:

• Mystical Knowledge

Key ideas:

• Ockham's Razor: plurality is not to be posited without necessity. The simplest explanation sufficient to account for the facts is to be preferred. A powerful principle of parsimony, named after Ockham but given its familiar Latin wording by later scholastics.
• Rejection of Universals: Only individual, particular things exist. 'Humanity' is not a thing shared by all humans but a term we use to group similar individuals — universals are in the mind, not in reality.
• Ockham on Divine Will: Ockham paired his nominalism with a strong voluntarism: no eternal natures stand over God's will, so an act is obligatory because God commands it and God could have commanded otherwise. The two commitments reinforce each other in his work, but neither entails the other — Buridan was a nominalist who did not follow him here.

Reacts to:

• Medieval Realism

Holds:

• Nominalism — Question scope: The Problem of Universals

Key ideas:

• Universals as Real: General knowledge is not explained by words alone; particulars have real features that can be understood universally.
• Several Realist Accounts: Medieval realists disagreed about whether and how universals exist before, in, or after particular things.
• A Historical Camp: The current was defined partly through its dispute with nominalist approaches, not by one uniform doctrine.

Influenced by:

• Platonism

Holds:

• Scholastic Realism

Key ideas:

• Li and Qi: Zhu Xi's framework: li 理 (principle, pattern; a different word from the li 禮 of ritual propriety in classical Confucianism) gives things their nature and structure; qi (material force) gives them their physical existence. Together they constitute all reality.
• Investigation of Things: Zhu Xi's Investigation of Things extends knowledge through careful study of patterns in things, events, and classics. Wang Yangming later rejected Zhu's version of this inquiry.
• Unity of Knowledge and Action: Wang Yangming argued that knowing the good and doing the good are one and the same — if you truly know something is right, you act on it. Inaction reveals incomplete knowledge.

Influenced by:

• Confucianism — Zhu Xi fixed the canon on four texts — the Analects, the Mencius, the Great Learning and the Doctrine of the Mean — and wrote the commentaries read alongside them; the programme of investigating things is drawn from a line in the Great Learning.
• Buddhism — Zhu Xi studied Chan Buddhism in his youth, and traces of Huayan Buddhism's holistic thought can be discerned in the way he built his synthesis.
• Taoism — Zhou Dunyi's Explanation of the Diagram of the Supreme Ultimate adapts a diagram of Taoist origin, and the Neo-Confucian cosmology of the Supreme Ultimate and qi draws on Taoist cosmological thought.

Key ideas:

• Scholastic Disputation: In Scholastic Disputation, a question is posed, objections are listed, a determination is given, and each objection is answered.
• Aquinas's Five Ways: Five arguments for God's existence from motion, causation, contingency, degrees of perfection, and teleology — grounding natural theology in Aristotelian philosophy.
• Natural Law: Aquinas argued that moral law is discoverable by reason, not only by revelation. The natural law participates in God's eternal law and is accessible to all rational beings.

Influenced by:

• Patristics
• Peripatetic School — The twelfth- and thirteenth-century Latin recovery of Aristotle's works gave the schools the framework they worked in — hylomorphism, the four causes, and demonstration from prior premises — and theological questions were then posed in those terms.
• Medieval Islamic Philosophy — From about 1230 Latin masters read Aristotle through Averroes's commentaries, which became the principal secondary literature of the universities once the Paris arts faculty made all of Aristotle's known works required reading in 1255.
• Medieval Jewish Philosophy — Maimonides' Guide of the Perplexed shaped Aquinas's handling of faith and reason and of proofs for God's existence.

Reacts to:

• Averroism — The engagement is that of thirteenth-century theologians with the Paris arts masters: Aquinas's De unitate intellectus contra Averroistas (1270) rebutted Siger of Brabant's thesis of one intellect shared by all humans, and Bishop Étienne Tempier's condemnations of 1270 and 1277 censured it along with the eternity of the world.

Holds:

• Moderate Realism — Question scope: The Problem of Universals
• Theism — Question scope: The Existence of God

Key ideas:

• Fana (Annihilation): The dissolution of the ego-self in God. As Al-Hallaj declared, 'Ana al-Haqq' (I am the Truth/God) — not self-aggrandizement but the complete disappearance of self.
• Wahdat al-Wujud: The doctrine drawn from Ibn Arabi — there is only one Being (God), and the world is the self-disclosure of the divine names and attributes. Multiplicity is the mirror of divine unity. Ibn Arabi never used the phrase himself; his later followers and critics coined it as the name for his teaching.
• Divine Love: Rabia al-Adawiyya pioneered the Sufi theology of pure love: 'O God, if I worship You for fear of Hell, burn me in Hell. If I worship You in hope of Paradise, exclude me from Paradise.'

Influenced by:

• Medieval Islamic Philosophy — The engagement is that of the later Sufis, Ibn Arabi above all, who cast his teaching in the philosophers' technical vocabulary — wujud for being, and the distinction between what exists necessarily and what exists only possibly — turning those terms to mystical ends.
• Neoplatonism — Ibn Arabi drew on Neoplatonic terminology to support his teaching of the unity of being. — Uncertain: How far this makes his thought Neoplatonic is disputed: his account of the world as a series of divine self-manifestations does not follow a Plotinian scheme of emanation.

Holds:

• Mystical Knowledge

Key ideas:

• Vajrayana: The 'Diamond Vehicle' — a set of advanced practices (deity yoga, mantra, visualization) that can accelerate the path to enlightenment within a single lifetime.
• Lamrim: The 'stages of the path' systematize the entire Buddhist path from initial motivation to full enlightenment, making the vast teachings accessible and progressive.
• Bardo: The intermediate states between death and rebirth — described in the Tibetan Book of the Dead as opportunities for liberation through recognition of the mind's true nature.

Influenced by:

• Mahayana
• Madhyamaka — Tibetan translators preserved a large body of Indian Madhyamaka treatises, which shaped Tibetan scholastic thought, and Tibetan scholars later named Chandrakirti's line of interpretation the Prāsaṅgika school.
• Yogacara — Tibetan doxographers sorted Indian Yogācāra into its branches and classed the synthesis of Śāntarakṣita and Kamalaśīla, which treats mind-only as a provisional teaching on the way to Madhyamaka emptiness, as Yogācāra-Svātantrika-Madhyamaka.

Key ideas:

• Virtù: Machiavellian virtù is the flexible skill, energy, and judgment needed to act effectively as fortune and political circumstances change; it is not the same as conventional moral virtue.
• Effectual Truth: Machiavelli turns from imagined ideal regimes to the observable conduct and historical experience of political life, especially when asking how rulers acquire and maintain power.
• Republican Liberty: In the Discourses, liberty depends on laws and institutions that channel participation and conflict between the people and elites instead of eliminating political disagreement.

Influenced by:

• Renaissance Humanism

Key ideas:

• Microcosm and Macrocosm: Renaissance and later Hermetic reception linked the human being and the larger cosmos through relations of correspondence. The familiar phrase "as above, so below" is a modern paraphrase of the Emerald Tablet rather than a sentence from the Corpus Hermeticum.
• Prisca Theologia: The belief that a single, ancient theology was given to humanity at the dawn of time and fragments of it are preserved in all wisdom traditions.
• Spiritual Transformation: Through gnosis (direct spiritual knowledge), the adept can ascend through the celestial spheres, shedding material limitations and reuniting with the divine source.

Influenced by:

• Neoplatonism
• Platonism — Ficino translated the Corpus Hermeticum for Cosimo de' Medici in 1463, before the Plato he had been hired to translate, and read the Hermetica as the ancient theology from which Plato had learned; the Renaissance current was Platonist in its reading of Hermes from the start.

Key ideas:

• Dignity of Man: Pico's vision: God placed humans at the center of creation with no fixed nature, free to ascend to the divine or descend to the bestial. We are the sculptors of ourselves.
• Studia Humanitatis: The core humanist curriculum — grammar, rhetoric, poetry, history, and moral philosophy — drawn from classical sources. Education forms the complete, virtuous human being.
• Critical Philology: Valla and Erasmus applied rigorous textual criticism to classical and biblical texts, demonstrating that careful reading of sources can overturn centuries of received opinion.

Influenced by:

• Platonism

Reacts to:

• Scholasticism — The humanists defined their programme of eloquence and classical learning against scholastic dialectic and its Latin, from Petrarch's attack on the schoolmen to Valla's assault on scholastic logic, though, as Kristeller showed, the two remained parallel strains with different subjects.

Key ideas:

• Tabula Rasa: Locke's image: the mind at birth is a blank slate. All ideas come from sensation (external experience) or reflection (internal experience). There are no innate ideas.
• Hume's Fork: All genuine propositions are either 'relations of ideas' (mathematics, logic — certain but empty) or 'matters of fact' (empirical — informative but uncertain). Everything else is sophistry.
• Problem of Induction: Hume showed that no amount of past experience logically guarantees future events. That the sun has risen every day gives no logical proof it will rise tomorrow.

Influenced by:

• Medieval Nominalism — Inherited the nominalist rejection of real universals and its restriction of knowledge to particular things, which empiricism recast as knowledge grounded in particular sense experience.
• Pyrrhonism — The early-modern revival of Pyrrhonian skepticism (via Sextus) sharpened empiricism's doubts about how far the senses warrant knowledge; Hume presented his own mitigated skepticism as, in part, the result of Pyrrhonian doubt corrected by common sense and reflection.

Holds:

• Humean Regularity — Question scope: The Nature of Causation — This is Hume's view: the idea of necessary connection comes not from anything observed in the objects but from the mind's habit of expecting the usual effect once it has seen two kinds of event constantly joined.
• Empiricism — Question scope: Experience or Reason?
• Bundle Theory — Question scope: Persistence of the Self — This is Hume's view, not Locke's: looking inward, Hume reported that he could never catch himself without a perception, and could observe nothing but the perceptions themselves.
• Psychological Continuity — Question scope: Persistence of the Self — This is Locke's view, not Hume's: a person reaches as far back as consciousness can extend to past thoughts and actions, whether or not the same substance underlies them.

Key ideas:

• Cogito Ergo Sum: Descartes's foundational insight: even if an evil demon deceives me about everything, the very act of doubting proves that I, the thinker, must exist.
• Innate Ideas: The mind possesses ideas not derived from experience — concepts of God, substance, infinity, and mathematical truths are innate, placed in us by God or inherent in reason.
• Method of Doubt: Systematically doubt everything that can possibly be doubted — only what survives this radical skepticism can serve as a foundation for certain knowledge.

Influenced by:

• Scholasticism

Reacts to:

• Pyrrhonism — Descartes' methodic doubt confronted the revived Pyrrhonian skepticism head-on, pushing doubt to its limit to reach an indubitable foundation that would answer it.

Holds:

• Rationalism — Question scope: Experience or Reason?
• Substantial Self — Question scope: Existence of the Self

Key ideas:

• State of Nature: A thought experiment: what would life be like without government? Hobbes saw war; Locke saw freedom constrained by inconveniences; Rousseau saw noble simplicity corrupted by civilization.
• Consent of the Governed: Legitimate political authority derives not from divine right or force but from the rational consent of the people who are governed.
• Natural Rights: Locke argued that individuals possess inherent rights to life, liberty, and property that no government may violate — ideas that shaped the American Revolution and its declarations of rights.

Influenced by:

• Stoicism
• Machiavelli's Political Thought — Took the realist account of power and self-interested human nature — sharpened by Machiavelli — as the pre-political condition the contract is designed to master, most directly in Hobbes.

Holds:

• Contractarianism

Key ideas:

• Substance Monism: There is only one substance — God or Nature — with infinite attributes, of which we know two: thought and extension. Everything that exists is a mode of this single substance.
• Conatus: Every being strives to persist in its own being (conatus). This striving is the essence of each thing and the foundation of Spinoza's psychology and ethics.
• Freedom Through Understanding: We are 'free' not by escaping determinism but by understanding our place in nature. The more we understand, the less we are enslaved by passive emotions.

Influenced by:

• Continental Rationalism — Spinoza worked inside Descartes' programme before turning it against him, keeping the geometrical order of demonstration and the appeal to clear and distinct ideas while rejecting the plurality of substances they had been used to defend.
• Medieval Jewish Philosophy — Spinoza studied Maimonides' Guide of the Perplexed closely, absorbing its rationalist theology even as he pushed past it to identify God with Nature.

Holds:

• Spinozistic Substance Monism — Question scope: How Many Fundamental Substances?

Key ideas:

• Reason and Criticism: Every institution — religious, political, social — must justify itself before the tribunal of reason rather than rest on tradition or revealed authority alone.
• Religious Toleration: Voltaire's campaigns against intolerance and judicial abuse argued that liberty of conscience is a precondition of a just society, not a threat to it.
• The Encyclopédie: Diderot and d'Alembert's vast collaborative project aimed to compile and popularize human knowledge, treating the spread of reason itself as an engine of progress.

Influenced by:

• British Empiricism — Voltaire's admiration for Locke and Newton carried British empiricism's trust in observation and its critique of inherited authority into the philosophes' program.
• Continental Rationalism

Key ideas:

• Transcendental Idealism: Space and time are the a priori forms of human sensible intuition, while the categories are a priori concepts through which the understanding organizes experience. Neither gives theoretical cognition of things as they are in themselves.
• Categorical Imperative: 'Act only according to that maxim whereby you can at the same time will that it should become a universal law.' Morality is grounded in rational duty, not consequences or desires.
• Synthetic A Priori: Kant argues that some knowledge is both informative about the world (synthetic) and knowable independent of experience (a priori) — mathematics and the principles of natural science.

Influenced by:

• Continental Rationalism
• British Empiricism — Kant took up Hume's problem about cause and effect: reason cannot show a priori why, if one thing is given, another must necessarily follow, so Hume traced the felt necessity to a habit formed by repeated experience. Kant widened the problem from causation to every concept by which the understanding connects things a priori.

Holds:

• Transcendental Idealism — Question scope: Space, Time, and Experience
• Kantian Deontology — Question scope: The Basis of Right Action

Key ideas:

• State and Authority: Some anarchists argue that no state can possess legitimate authority; others make a contingent case against existing states or allow that limited authority could meet a demanding burden of justification.
• Hierarchy and Domination: Anarchist traditions extend criticism beyond government to different forms of domination and oppressive hierarchy, but they do not all draw the boundary of justified authority in the same place.
• Mutual Aid: Kropotkin argued that cooperation is an important factor in evolution and social flourishing, offering it as an alternative to accounts that make competition the sole driver.
• Political Practice: Voluntary association, direct action, and prefigurative organization are important anarchist approaches, while anarchists continue to disagree about nonviolence, revolutionary force, and gradual reform.

Influenced by:

• Classical Utilitarianism

Reacts to:

• Social Contract Tradition — Contested the contract theorists' case that the state rescues people from an anarchic state of nature, answering that the state produces its own oppression and violence. Godwin, the tradition's forerunner, built on Locke's allowance for revolution against a despotic state to argue that government is not necessarily better than anarchy.
• Marxism — The Bakunin–Marx split at the First International crystallized a lasting opposition between libertarian and authoritarian socialism, anarchism rejecting the transitional state Marx accepted.

Key ideas:

• The Absolute: Reality is a single, all-inclusive, rational whole. Individual things, taken in isolation, are abstractions from that whole.
• Internal Relations: Relations help constitute the things they relate rather than merely connecting already independent items.
• Coherence Theory of Truth: Truth is understood through the coherence of beliefs within a comprehensive system.

Influenced by:

• German Idealism — Stirling's The Secret of Hegel (1865) opened a sustained British reception of Hegel, from which Green, Bradley and Bosanquet built their own systems of the Absolute.

Holds:

• Absolute Idealism
• Coherence Theory of Truth — Question scope: The Nature of Truth — Joachim stated it in The Nature of Truth (1906); Bradley is usually counted with him, though one reading credits Bradley with an identity theory of truth instead.

Key ideas:

• Greatest Happiness Principle: Actions are right insofar as they tend to promote happiness (pleasure and absence of pain), wrong insofar as they tend to produce the reverse — calculated impartially across all affected.
• Higher and Lower Pleasures: Mill argued: 'It is better to be Socrates dissatisfied than a fool satisfied.' Intellectual and moral pleasures are qualitatively superior to mere bodily satisfaction.
• Consequentialism: The moral value of an action lies entirely in its consequences — not in the agent's motives, the act's intrinsic nature, or adherence to rules.

Influenced by:

• British Empiricism
• Epicureanism — Mill defended the greatest-happiness principle against the charge of being 'a doctrine worthy only of swine' by invoking the Epicureans, who had answered the same charge; the school's identification of the good with pleasure descends from that hedonist ancestry.
• French Enlightenment

Holds:

• Utilitarian Distribution — Question scope: Distributive Justice
• Consequentialism — Question scope: The Basis of Right Action

Key ideas:

• Hegel's Dialectic: Thought and reality develop through contradiction and resolution. Hegel described that development as a movement of negation and sublation (Aufhebung), in which a concept's own limits drive it into a richer and more concrete form that keeps what the earlier one had established. The familiar "thesis-antithesis-synthesis" formula is not his — the triad is Fichte's language, which Heinrich Moritz Chalybäus later applied to Hegel, and Hegel never used it to describe his own method.
• Absolute Spirit: Hegel's vision: all of history is the progressive self-realization of Spirit (Geist), moving through art, religion, and philosophy toward complete self-knowledge.
• Master-Slave Dialectic: Hegel's famous analysis: self-consciousness arises only through recognition by another. The struggle for recognition between master and slave drives the development of freedom and culture.

Influenced by:

• Kantian Critical Philosophy — Took Kant's transcendental idealism as its starting point and tried to complete it as a system derived from a single first principle, beginning with Fichte's Wissenschaftslehre of 1794; Kant's own critical philosophy is the separate entry it presupposes.
• Spinozism — The young idealists took up Spinoza's monism once the Pantheism Controversy of the 1780s had made it a central question of German philosophy. Schelling above all took from it the demand for a single unconditioned ground of everything, while trying to escape the fatalism Jacobi had found in it.

Holds:

• Idealism — Fichte, Schelling, and Hegel radicalized Kant's transcendental idealism: a thing must be an object for consciousness to be an object at all, so mind or spirit is constitutive of reality's knowable form.

Key ideas:

• Historical Materialism: Modes of production and class relations condition law, politics, and dominant forms of thought. The framework gives material production explanatory importance without reducing every historical change to a one-way, mechanical effect of the economic base.
• Alienation: Under capitalism, workers are alienated from their labor, its products, their fellow workers, and their own human potential — reduced to commodities in the production process.
• Class Struggle: 'The history of all hitherto existing society is the history of class struggles.' Social change comes through conflict between those who own the means of production and those who labor.

Influenced by:

• German Idealism — Took over Hegel's dialectic but inverted it — from the self-movement of spirit to the development of material and economic conditions.

Holds:

• Injustice as Exploitation — Question scope: Structural Injustice — The subject is the tradition rather than Marx alone: his own texts analyse surplus extraction without explicitly calling capitalism unjust, while later Marxists state the wrong itself as unjust appropriation.
• Atheism — Question scope: The Existence of God — Marx took over Feuerbach's view that people invented God in their own image, and treated religion as a response to alienated material life that will wither away once that life is emancipated.

Key ideas:

• Back to Kant: Philosophy is a critical theory of knowledge, independent of psychology, that seeks the a priori concepts and principles that make the sciences possible, without treating Kant's own list of them as complete or fixed.
• Nomothetic vs Idiographic: Windelband's distinction between sciences that seek general laws and those that study unique, unrepeatable phenomena — foundational for the methodology of the human sciences.
• Philosophy of Symbolic Forms: Cassirer's argument that human experience is constituted through diverse symbolic systems — language, myth, art, science — each forming a distinct and valid mode of world-making.

Revives:

• Kantian Critical Philosophy — The rallying cry came from Otto Liebmann's Kant und die Epigonen (1865), which ends each chapter with the demand to go back to Kant — a renewal aimed at the idealist successors who claimed to have completed the critical philosophy.

Key ideas:

• Death of God: Nietzsche's phrase for the collapse of belief in the Christian God. He traced it to Christianity itself: its morality's ever stricter demand for truthfulness, refined into the scientific conscience, made the belief untenable, and the morality built on that belief lost its foundation.
• Devaluation of Values: Nihilism emerges when the highest inherited values cease to command belief or provide an authoritative purpose.
• Overcoming Nihilism: Nietzsche treated the crisis as a challenge to create and reassess values rather than as a conclusion to accept passively.

Responds to:

• The Meaning of Life — The current's answer is a diagnosis rather than a doctrine: the inherited religious and metaphysical sources of meaning have lost their authority, so the question cannot be answered in the old terms. Nietzsche treated that collapse as a crisis to be overcome by a revaluation of values, not as the conclusion that nothing matters — which is why this current is not itself the position that life has no meaning.

Key ideas:

• Will as Thing-in-Itself (Schopenhauer): The inner nature of everything is Will — not rational purpose but blind, irrational striving. Everything in nature, from gravity to human desire, is a manifestation of this Will. Liberation comes through aesthetic contemplation, compassion, and ultimately denial of the will to live.
• Will to Power (Nietzsche): Nietzsche recast willing in terms of competing drives and will to power while rejecting Schopenhauer's unitary metaphysical Will and ideal of its denial.
• The Unconscious Will (Hartmann): Eduard von Hartmann synthesised Schopenhauer's Will with Hegel's Idea, proposing an unconscious absolute that strives blindly but unfolds with logical structure — a bridge between pessimist metaphysics and systematic philosophy.

Influenced by:

• Kantian Critical Philosophy — Schopenhauer builds directly on Kant's distinction between appearance and thing-in-itself, keeping the distinction and identifying the thing-in-itself as Will. He set out the debt and the disagreement together in the Appendix to the first volume.

Responds to:

• Free Will — Schopenhauer denies the liberty of indifference: every act follows necessarily from the character meeting a motive, and freedom belongs not to acting but to being, to the intelligible character that the will is as thing-in-itself.

Key ideas:

• Law of Three Stages: Human thought evolves from theological (divine explanations) through metaphysical (abstract forces) to positive (scientific laws based on observation). Each stage replaces the last.
• Anti-Metaphysics: Questions about ultimate reality, first causes, or essences lie beyond the reach of positive knowledge and belong to a superseded stage of thought. Science describes regularities in observable phenomena — nothing more is needed or possible.
• Positive Method: Scientific value lies in method rather than fixed doctrine. Comte's Positive Method takes different forms across the sciences while seeking observable laws that support prediction.

Influenced by:

• British Empiricism

Key ideas:

• Imagination: Many Romantics treated creative imagination as more than mere fancy: it could bring subject and object, or finite experience and an infinite whole, into a provisional unity.
• The Sublime: Encounters with vast, overwhelming natural phenomena (storms, mountains, oceans) evoke a mixture of terror and awe that reveals the infinite within us.
• Organic Wholeness: Romantic accounts of nature often opposed purely mechanistic explanation by treating parts as intelligible through their relations within a living whole.

Influenced by:

• Kantian Critical Philosophy

Holds:

• Expression Theory of Art — Question scope: The Definition of Art

Key ideas:

• Self-Reliance: Trust your own inner voice over social conformity. 'Whoso would be a man must be a nonconformist.' Imitation is suicide; each person must find and follow their own genius.
• The Oversoul: All individual souls participate in one universal spirit — the Oversoul — connecting every person to every other and to nature itself.
• Civil Disobedience: Thoreau argued that when the law is unjust, the moral individual has a duty to resist. His ideas later inspired Gandhi and Martin Luther King Jr.

Influenced by:

• Romanticism
• Kantian Critical Philosophy — Emerson took three of Kant's claims, learned at second hand through Coleridge, Hedge and de Staël: the mind itself forms experience, that fact answers Locke's skepticism, and 'transcendental' names what makes experience possible rather than what lies beyond it. He blended them with Neoplatonism and post-Kantian idealism, and for many in the movement the word meant confidence in the mind's powers more than an inquiry into the conditions of experience.
• Vedic Philosophy

Key ideas:

• The Absurd: The absurd arises from the gap between humanity's need for order, purpose, and meaning and the world's refusal to provide any. It is not despair but a clear-eyed recognition of the human condition — and it demands an equally clear-eyed response.
• Revolt, Not Resignation: Camus's answer to the absurd is not passive acceptance but active revolt — continuing to live fully without appealing to a final or transcendent meaning.
• Sisyphean Affirmation: The myth of Sisyphus, condemned to push a boulder uphill for eternity, becomes Camus's central image. In the moment Sisyphus walks back down the hill, conscious of his fate, he is superior to it. 'One must imagine Sisyphus happy.'

Influenced by:

• Nineteenth-Century European Nihilism

Reacts to:

• Existentialism — The leap Camus attacks in The Myth of Sisyphus is Kierkegaard's, Shestov's and Jaspers': each of them escapes the absurd by restoring the meaning its recognition had withdrawn. Camus argued that the absurd must be held open instead.

Holds:

• The Absurd — Question scope: The Meaning of Life

Key ideas:

• Changing Methods: Analytic philosophers have used different combinations of formal logic, conceptual analysis, ordinary-language inquiry, scientific evidence, and case-based argument. No single technique defines all analytic philosophy.
• Logical Analysis: Russell and Frege developed formal logic as a tool for philosophical analysis — revealing the true logical form of propositions hidden beneath their grammatical surface.
• Language and Meaning: Work by Russell, Frege, and both the early and later Wittgenstein made language central to major parts of the tradition, but with sharply different accounts of logical form, meaning, and use.

Influenced by:

• British Empiricism — Kept Locke's and Hume's demand that meaningful discourse answer to experience, but made the whole statement, rather than the single idea or term, the unit that must answer to it; Quine later widened that unit to the whole of science.
• Pragmatism

Reacts to:

• British Idealism — Moore and Russell rejected the doctrine of internal relations, on which a relation partly constitutes the terms it relates, and the coherence theory of truth that went with it. They argued instead that relations are external to their terms and that a true proposition can be analysed into independently real constituents rather than judged only by its coherence within a system of belief.

Key ideas:

• Duration: Lived time is a continuous qualitative development rather than a row of interchangeable instants.
• Memory and perception: Conscious experience selects and contracts a richer temporal field in response to the demands of action.
• Creative evolution: Life and novelty cannot be exhaustively represented as the rearrangement of fixed, pre-given possibilities.
• Intuition and intellect: Bergsonism distinguishes the practical, analytic work of intelligence from the direct experiential inquiry represented separately as Bergsonian Intuition.

Reacts to:

• Kantian Critical Philosophy — Time and Free Will is built as an attack on Kant's treatment of time as a homogeneous medium like space, and Bergson offers intuition as the metaphysical knowledge Kant had declared impossible.

Key ideas:

• Falsifiability: A theory earns scientific status by forbidding certain observations — if those observations occur, the theory is refuted. Theories immune to refutation are not thereby confirmed; they are unscientific.
• Conjectures and Refutations: Science proceeds by proposing bold conjectures and subjecting them to the most severe tests available, retaining only what survives — not by inductively generalizing from confirming instances.
• Fallibilism: No theory, however well corroborated, is ever proven true. All knowledge remains provisional and open to future refutation.

Reacts to:

• Logical Positivism — Where the positivists demarcated science by verifiability, Popper argued verification is impossible and that falsifiability is the mark of science, rejecting inductivism as a myth of method.

Holds:

• Falsificationism — Question scope: Science and Pseudoscience

Key ideas:

• Dialectic of Enlightenment: The Enlightenment's drive to dominate nature through reason has turned against itself, producing new forms of domination — bureaucracy, propaganda, the culture industry.
• Culture Industry: Mass culture (film, radio, advertising) is not spontaneous but manufactured to pacify, standardize, and control. Entertainment becomes a tool of social domination.
• Communicative Rationality: Habermas argues that genuine rationality is not instrumental but communicative — grounded in open, undistorted dialogue aimed at mutual understanding and consensus.

Influenced by:

• Marxism — Horkheimer's 1937 essay takes Marx's critique of political economy as its model for what a theory should be: not detached observation, but analysis that knows itself to be produced by the society it examines and aimed at changing it.
• German Idealism
• Phenomenology

Responds to:

• Structural Injustice — Frankfurt School critique treats domination not just as legal inequality but as ideology and administered culture that reproduce unfreedom; its guiding interest is emancipation — the abolition of social injustice and of 'all forms of domination'.

Key ideas:

• Logocentrism: Western thought privileges presence, speech, and the logos (reason) over absence, writing, and the material. Derrida shows this privilege is unjustifiable and self-undermining.
• Trace and Différance: No sign is self-present. Every sign bears the 'trace' of what it differs from and defers to. Meaning is always already contaminated by absence and difference.
• Supplementarity: The 'supplement' (what is supposedly added to something complete) reveals that the original was never complete. Writing 'supplements' speech, exposing speech's own incompleteness.

Influenced by:

• Phenomenology

Reacts to:

• Structuralism — Derrida's 1966 lecture 'Structure, Sign, and Play' attacked the structuralist assumption of a stable center, turning structuralism's own tools against it.

Key ideas:

• Intrinsic Value of Nature: Nature has value in itself, not merely as a resource for human use. Rivers, forests, and species deserve moral consideration independent of their utility.
• Deep Ecology: Naess distinguished 'shallow' environmentalism (protecting nature for human benefit) from 'deep' ecology (recognizing the equal right of all life forms to flourish).
• Land Ethic: Leopold: 'A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise.'

Influenced by:

• Romanticism
• Transcendentalism
• Buddhism — Naess placed Buddhism among the ultimate premises from which the deep ecology platform can be derived, alongside Christianity and Spinoza's philosophy.

Holds:

• Ecocentric Holism — Question scope: Moral Standing in Nature

Key ideas:

• Sartre on Existence and Freedom: Sartre argued that people are not born with a predetermined essence and must define themselves through choices made within the limits of their situation. His language of radical freedom does not erase embodiment, history, or other features of facticity.
• Sartrean Bad Faith: Sartre used this term for self-deception that denies either freedom or the facts and limits of one's situation, as when a person treats a social role as a complete and fixed identity.
• Authenticity: Existentialists used different accounts of authenticity, but commonly opposed passive conformity and asked how a person can own a situated life in the face of anxiety, mortality, and responsibility.

Influenced by:

• Phenomenology — This is the twentieth-century wing rather than Kierkegaard: Heidegger, Sartre and Beauvoir took over Husserl's descriptive study of lived experience and his account of consciousness as always directed at something, and turned both on concrete human existence. Sartre subtitled Being and Nothingness an essay in phenomenological ontology.
• Philosophies of the Will — The twentieth-century existentialists took from Nietzsche an ideal of authenticity as self-creation: the overman who breaks with the herd, creates his own values, and gives his life a style of its own. Camus read that affirmation of life as a form of rebellion against conformity.
• Nineteenth-Century European Nihilism — This is the twentieth-century existentialists' engagement, not Kierkegaard's, whose work came first. Sartre and Beauvoir took the diagnosis that inherited religious and moral values have lost their authority as the predicament a free person must answer by creating values, not as proof that nothing matters.

Reacts to:

• German Idealism

Holds:

• Existential Meaning — Question scope: The Meaning of Life

Key ideas:

• Gender as Construct: De Beauvoir argued that femininity is not a biological given but a social construction. Butler radicalized this insight, arguing that gender is performative — constituted through repeated acts rather than expressing an inner essence.
• Intersectionality: Coined by Kimberlé Crenshaw, this concept insists that gender cannot be understood in isolation from race, class, sexuality, and other axes of oppression. bell hooks and other Black feminist thinkers showed that mainstream feminism often universalized the experience of white, middle-class women.
• Ethics of Care: Carol Gilligan and Nel Noddings challenged the dominance of abstract, rule-based ethics (Kantian and utilitarian) by foregrounding care, relationships, and responsiveness to particular others as central moral concerns.

Influenced by:

• Existentialism — This is Beauvoir's engagement rather than Wollstonecraft's: The Second Sex borrows the vocabulary of freedom, situation and bad faith to argue that women are cast as the Other and held in immanence instead of the open future a free project requires.
• Social Contract Tradition
• Critical Theory — This is the engagement of feminist critical theorists from the 1980s, not of the movement's first writers. Nancy Fraser took up Marx's view that social theory should clarify the struggles of its age to argue that the Frankfurt School must answer to the women's movement, faulting Habermas for leaving gender untheorized, and Seyla Benhabib pressed the same objection.
• Post-Structuralism — Butler took up Foucault's point that systems of power produce the subjects they claim only to represent, and argued from it that sex, not just gender, may be culturally constructed.

Responds to:

• Structural Injustice — Feminist philosophy analyses patriarchy as a structure that distributes advantage and burden by gender across institutions rather than through individual wrongs, so gender injustice is treated as structural; the tradition carries several accounts of what makes the structure unjust rather than one named position.

Key ideas:

• Hermeneutic Circle: We understand the parts through the whole and the whole through the parts. Understanding is circular: every interpretation presupposes prior understanding, which is revised through further interpretation.
• Fusion of Horizons: Understanding is not reproducing an author's original intention but a productive encounter between the reader's 'horizon' (historical situation) and the text's horizon.
• Productive Prejudice: Gadamer rehabilitates 'prejudice' (Vorurteil): pre-understandings are not only obstacles to truth but the very conditions that make understanding possible. Some prejudices do mislead; the text's resistance and the distance of time are what sort the productive ones from the misleading.

Influenced by:

• Phenomenology — This is the twentieth-century phase rather than Schleiermacher's: Heidegger recast understanding as a basic way of being in the world rather than a technique for reading texts, and Gadamer built Truth and Method on that recasting.
• Romanticism

Reacts to:

• Positivism

Key ideas:

• Absolute Nothingness: Nishida's key concept: the ground of reality is not Being (as in Western metaphysics) but absolute nothingness — the 'place' (basho) in which all determinations arise and return.
• Self-Awakening: True self-knowledge is not reflective consciousness but a direct, non-dual awareness — the self knowing itself in and through absolute nothingness.
• Overcoming Nihilism: Nishitani argued that Western nihilism can be overcome not by returning to theism but by passing through nihilism into the Buddhist experience of sunyata (emptiness) — a creative, affirmative nothing.

Influenced by:

• Zen (Chan) — Nishida studied Western philosophy alongside a dedicated practice of Zen, and the school states in Western philosophical terms what Zen approaches through sitting: a nothingness disclosed when the division between knower and known gives way.
• Phenomenology
• Existentialism

Key ideas:

• Verification Principle: A non-tautological statement is meaningful only if observation could in principle verify it conclusively. 'The Absolute is perfect' fails this test.
• Elimination of Metaphysics: Traditional philosophical questions (Does God exist? What is the essence of Being?) are not false but meaningless — they violate the conditions for cognitive significance.
• Unity of Science: All genuine sciences share a common language and method. The distinctions between physics, biology, and psychology are practical, not fundamental.

Influenced by:

• Positivism — The Circle formed around Ernst Mach's legacy — Schlick was appointed to the Vienna chair Mach had held, and the group's public society was named for him — and took over both his demand that scientific claims answer to observation and Comte's verdict that questions about first causes and essences lie outside knowledge.
• British Empiricism
• Neo-Kantianism — Carnap, who studied Kant with Bruno Bauch and heard Rickert lecture, took over the question of how objective knowledge is possible: his dissertation Der Raum (1922) kept a Kantian 'necessary form' of space, and the Aufbau (1928) sought a basis for scientific objectivity despite knowledge's subjective starting point in perception.
• Analytic Philosophy — Frege's logic, Russell's logicism, and Wittgenstein's Tractatus were foundational for the Vienna Circle's programme of logical analysis.

Holds:

• Verificationism — Question scope: Meaningful and Meaningless Statements
• Confirmability Criterion — Question scope: Meaningful and Meaningless Statements — This is the view of the Circle's left wing — Carnap, Hahn, Frank and Neurath — which from about 1931 set itself apart from the more conservative wing around Schlick over how far the criterion should be loosened.

Key ideas:

• Anti-Representationalism: Rorty: the mind does not 'mirror' nature. Knowledge is not a representation of reality but a set of practices for coping with the world. Drop the mirror metaphor.
• Solidarity Over Objectivity: We should not seek to transcend our community's standards to reach 'objective truth' but instead expand the community of conversation and deepen mutual understanding.
• Inferentialism: Brandom: the meaning of a concept is determined by its role in inferences — what it follows from and what follows from it — not by what it refers to.

Influenced by:

• Pragmatism — Rorty called Dewey one of the three most important philosophers of the century, and Philosophy and the Mirror of Nature carries Dewey's attack on the spectator theory of knowledge into its case against analytic epistemology.
• Analytic Philosophy
• Post-Structuralism

Key ideas:

• Moral Metaphysics: Mou Zongsan: Confucianism has a 'moral metaphysics' grounded in the direct experience of the moral mind, which is accessible through self-cultivation.
• Self-Negation of Innate Moral Knowing: Innate moral knowing (liangzhi) must 'negate itself' — temporarily set aside moral subjectivity — to make room for cognitive objectivity, science, and democratic institutions.
• Confucian Modernity: New Confucians argue that modernization need not mean Westernization. Confucian values (community, moral cultivation, filial devotion) can ground a distinctive Asian modernity.

Influenced by:

• Neo-Confucianism — The New Confucians understood themselves as the third era of Confucian thought after the Song–Ming Neo-Confucians, and took their bearings from Wang Yangming's learning of the heart-mind while demoting Zhu Xi.
• Kantian Critical Philosophy — Mou Zongsan translated Kant's three Critiques and built his moral metaphysics as a reconstruction of Kant: where Kant left freedom a postulate that cannot be known, Mou argued that the Confucian heart-mind knows it practically, through intellectual intuition.
• Yogacara — Xiong Shili studied Yogācāra Buddhism before reworking its 'consciousness-only' philosophy into the Confucian metaphysics of his New Treatise (1932), while rejecting the Buddhist view that evil is innate to human nature.

Key ideas:

• Speech Acts: Austin showed that language does not merely describe the world — it acts upon it. 'I promise,' 'I pronounce you married,' and 'I bet you' are performative utterances that accomplish something in their very saying. Austin first set them apart from statements, which are true or false, then gave up the split: stating is also something done with words, and his general theory of speech acts covers both.
• Category Mistakes: Ryle argued that the mind-body problem rests on a category mistake — treating 'the mind' as if it were a thing of the same logical type as 'the body.' Asking where the mind is, is like asking where the university is after being shown all its buildings.
• Therapeutic Dissolution: Following the later Wittgenstein's insight that philosophical problems are often 'bewitchments' of language, ordinary language philosophers aimed not to solve traditional problems but to show them to be illusions born of linguistic confusion.

Influenced by:

• Analytic Philosophy — Took over the founding analytic move of treating philosophical questions as questions about language, and the practice of piecemeal conceptual analysis, applying both to everyday usage rather than to the logical form Russell and Frege sought beneath it.

Reacts to:

• Logical Positivism — Against the positivists' project of an ideal formal language, Austin and Ryle argued that ordinary language works well and that forcing it into a logical calculus creates the very problems it claims to solve.

Holds:

• Meaning as Use — Question scope: The Grounds of Linguistic Meaning

Key ideas:

• Intentionality: Consciousness is always consciousness of something. The mind is not a container: every mental act (perceiving, imagining, judging) is directed at an object.
• Phenomenological Reduction: Husserl's epoché and reduction, the Phenomenological Reduction, suspend use of ordinary commitments about existence in order to examine how objects are given to consciousness.
• Being-in-the-World: Heidegger argued that our primary relation to the world is not theoretical contemplation but practical engagement — we are always already situated in a meaningful context of tools, projects, and others.

Influenced by:

• Kantian Critical Philosophy
• Neo-Kantianism
• British Empiricism — Husserl read Hume's analysis of experience as an unwitting anticipation of phenomenology, and inherited the notion of intentionality from Brentano's descriptive psychology, itself rooted in the empiricist attention to experience, before transforming it into an a priori science of consciousness.

Key ideas:

• Différance: Derrida's neologism: meaning is always deferred, never fully present. Every sign refers to other signs in an endless chain — there is no transcendental signified anchoring the system.
• Power/Knowledge: Foucault: power is not merely repressive but productive — it produces knowledge, truth, and subjects. What counts as 'true' is shaped by systems of power.
• Rhizome: Deleuze and Guattari's alternative to hierarchical thinking: knowledge and reality are rhizomatic — non-hierarchical, multiply connected, with no center or foundation.

Influenced by:

• Phenomenology
• Marxism — Adapted the Marxist analysis of ideology and power — via Althusser — while rejecting its economic determinism and totalizing philosophy of history.

Reacts to:

• Structuralism — Contested the claim that meaning rests on stable, universal, self-contained structures: Derrida and Foucault kept the analysis of systems of difference while arguing that no such system ever closes and that its oppositions are historically produced, not timeless.

Key ideas:

• Incredulity toward Metanarratives: Lyotard used this formulation for skepticism toward the large narratives that legitimate knowledge and institutions, including stories of progress and emancipation.
• Simulacra and Hyperreality: Baudrillard: in consumer society, copies without originals (simulacra) replace reality. Disneyland, media, advertising — the simulation becomes more real than the real.
• High and Popular Culture: In postmodern aesthetics, distinctions between high art and popular culture, original and copy, or depth and surface are often blurred or critically reworked.

Influenced by:

• Post-Structuralism — Extended the post-structuralist attack on totalizing systems and on stable reference: Lyotard turned it against the grand narratives that legitimate knowledge, Baudrillard against the sign that no longer refers to any original.

Key ideas:

• Pragmatic Maxim: Peirce: to clarify an idea, consider what practical effects its object might have. 'Our conception of these effects is the whole of our conception of the object.'
• Different Accounts of Truth: Peirce connected truth with the long-run goal of inquiry, James stressed how true ideas prove themselves within experience, and Dewey emphasized tested or warranted assertion. These views overlap but are not one theory of whatever happens to be useful.
• Inquiry as Problem-Solving: Dewey: thinking begins with a felt difficulty. Through inquiry — observation, hypothesis, experiment — we transform indeterminate situations into resolved ones.

Influenced by:

• British Empiricism
• Transcendentalism — Took from Emerson a way of doing philosophy as cultural criticism that turns away from European philosophy's preoccupation with the foundations of knowledge, together with his stress on human power to transform circumstances.
• Kantian Critical Philosophy — Peirce took the very word 'pragmatic' from Kant, and his system of categories and architectonic method are deeply indebted to the critical philosophy.

Holds:

• Pragmatist Theory of Truth — Question scope: The Nature of Truth — James extended the pragmatic maxim into a theory of truth; it is one of the school's problem-specific positions, not the whole of Pragmatism.

Key ideas:

• Process Over Substance: The basic units of reality are not enduring things but momentary events (actual occasions) that arise, experience, and perish — reality is a process of becoming, not a collection of beings.
• Prehension: Each actual occasion 'prehends' (grasps, incorporates) previous occasions, creating continuity. Experience is not limited to humans — it extends to the most basic events in nature.
• Creative Advance: The universe is fundamentally creative — each moment brings genuine novelty. Process philosophy rejects determinism and embraces the real openness of the future.

Influenced by:

• Pragmatism
• Bergsonism — Whitehead declared himself greatly indebted to Bergson, whose account of duration had already made becoming basic, and set out to rescue that kind of thought from the charge of anti-intellectualism.
• Platonism — Whitehead held that restating Plato's general point of view for two thousand years of later experience would require a philosophy of organism, and he kept Plato's idea of participation: temporal things arise by the ingression of eternal objects, the timeless potentials that give each actual occasion its definite form.
• German Idealism — Drew on Hegel's dialectical conception of becoming for a metaphysics in which reality is fundamentally process rather than static substance.

Holds:

• Process Metaphysics

Key ideas:

• Against Correlationism: Meillassoux's After Finitude (2006) names the trap and argues that the absolute can be thought after all, since mathematics describes a world indifferent to whether anyone thinks it.
• Object-Oriented Ontology: Harman: objects (of all kinds) have a hidden depth that withdraws from every relation. No object is exhausted by its effects on other things — reality exceeds all access.
• Ancestrality: Meillassoux: science tells us about events before any consciousness existed (the formation of stars, the age of rocks). This is a problem for correlationism but not for realism.

Reacts to:

• Kantian Critical Philosophy — Rejects correlationism — the post-Kantian thesis that we can only think the correlation of thought and being, never the world in itself — seeking access to a mind-independent reality.
• Phenomenology

Holds:

• Realism

Key ideas:

• Sign System: Meaning is produced not by the relation between words and things but by differences within a system of signs. Saussure's example: French mouton and English sheep can translate each other yet differ in value, because English also has mutton for the meat and French does not split them. Sounds work the same way: 'cat' is identified by its difference from 'bat' and 'cap'.
• Deep Structures: Beneath the surface variety of myths, kinship systems, and cultural practices lie universal, unconscious structures — binary oppositions that organize human thought.
• Decentering the Subject: The individual is not the author of meaning. Structures — linguistic, social, unconscious — speak through us rather than being created by us.

Influenced by:

• Marxism — Marxism shaped Althusser's and Barthes's structural analyses of ideology and culture, grafting the analysis of power onto the Saussurean model of the sign.

Key ideas:

• Character Over Rules: Ethics is fundamentally about developing virtuous character — courage, temperance, justice, generosity — not about following rules or maximizing outcomes.
• Practical Wisdom (Phronesis): The master virtue: the ability to perceive what the situation requires and respond appropriately. Virtue cannot be reduced to a formula; it requires judgment.
• MacIntyre's Narrative: Human life is a narrative quest for the good. Virtues are qualities that sustain us in that quest, and they can only be understood within specific practices and traditions.

Influenced by:

• Stoicism

Reacts to:

• Classical Utilitarianism — Anscombe's 1958 'Modern Moral Philosophy' argued that a morality fixated on rules and consequences is bankrupt without a prior account of human flourishing and character.
• Kantian Critical Philosophy

Revives:

• Peripatetic School — Anscombe's 1958 essay called for a return to Aristotle's ethical vocabulary — the virtues, practical wisdom (phronesis), and eudaimonia as flourishing — and Foot, MacIntyre and Hursthouse then rebuilt a full normative theory on those concepts.

Holds:

• Virtue Ethics — Question scope: The Basis of Right Action

Characteristic operations:

• Identify what needs explaining: State the observation, pattern, or fact that calls for an account.
• Generate live explanations: Form hypotheses that would make the evidence intelligible if they were true.
• Compare explanatory merits: Assess fit with the evidence together with virtues such as simplicity, scope, and coherence.
• Adopt a provisional hypothesis: Prefer or investigate the strongest explanation while keeping it open to testing and revision.

Characteristic operations:

• Fix the premises: State the starting claims explicitly, including the ones usually left unspoken.
• Check that the form preserves truth: Ensure the conclusion cannot be false while the premises are true.
• Distinguish validity from soundness: Ask separately whether the form is valid and whether the premises are actually true.
• Attack a conclusion at its source: Reject an unwanted valid conclusion by denying a premise, not the inference.

Characteristic operations:

• Assemble the cases: Collect observations, checking how varied and how numerous they are.
• Generalize beyond them: Extend the pattern to cases not yet observed.
• Assess the strength: Judge how strongly the evidence supports the conclusion, since support comes in degrees.
• Confront the justification problem: Face the question of what entitles the projection, given that past success is itself an inductive ground.

Characteristic operations:

• Identify dubitable beliefs: Begin with beliefs that depend on sources capable of error.
• Intensify the test: Use skeptical scenarios to expose assumptions that ordinary doubt leaves untouched.
• Withhold assent: Treat the vulnerable beliefs as unsettled for the purposes of inquiry.
• Find and rebuild: Seek a proposition resistant to the test and reconstruct claims from that basis.

Characteristic operations:

• Assume the claim: Treat the proposition under examination as true without yet endorsing it.
• Derive consequences: Follow what the assumption commits its defender to accepting.
• Expose the failure: Identify a contradiction, impossibility, or consequence the argument has independently shown to be unacceptable.
• Reject or revise: Logic shows only that the assumption and the other premises cannot all be true. Withdraw or qualify the assumption when the other premises are held more secure; otherwise the argument may count against one of them instead.

Characteristic operations:

• Gather considered judgments: Begin with case judgments made under conditions suitable for reflection.
• Formulate principles: Identify general rules that could explain and organize those judgments.
• Locate conflicts: Compare judgments, principles, arguments, and relevant background theories.
• Revise in either direction: Change a judgment, principle, or theory where doing so improves the whole.
• Test the wider view: Consider serious alternatives before treating the resulting coherence as adequate.

Characteristic operations:

• Construct the case: Specify an imagined situation with the features relevant to the question.
• Vary one feature: Hold other conditions steady while changing the point under examination.
• Run the scenario: Work out what would happen or what judgments the case elicits.
• Draw and test the inference: State the proposed lesson, then check whether hidden assumptions or misleading details drove it.

Characteristic operations:

• Fix the starting point: Identify an experience or capacity the inquiry treats as actual.
• Ask what it requires: Determine which structures or commitments would have to hold for that starting point to be possible.
• Rule out alternatives: Show why the phenomenon could not occur without the proposed condition.
• State the scoped conclusion: Claim necessity only relative to the established starting point.

Characteristic operations:

• Identify the target concept: State which concept is under analysis and what work it is meant to do.
• Propose an account: Formulate candidate conditions, components, or relations.
• Test cases: Compare clear, borderline, and imagined cases against the account.
• Revise the proposal: Narrow, broaden, or divide the account in response to counterexamples.

Characteristic operations:

• Identify the troublesome expression: Locate the word or phrase on which the philosophical problem turns.
• Collect ordinary uses: Compare how competent speakers use it across concrete situations.
• Mark distinctions: Notice contrasts, exceptions, and conditions that an abstract formulation suppresses.
• Reframe the problem: Decide whether the puzzle should be clarified, divided, or dissolved in light of those uses.

Characteristic operations:

• Begin from a defended thesis: Let an interlocutor or established school supply the claim under examination.
• Draw out commitments: Use questions or accepted premises to identify what the thesis requires.
• Construct the opposing case: Argue against the thesis, or argue both sides, without treating either case as one's settled doctrine.
• Expose the difficulty: Derive a contradiction, counterexample, or unresolved opposition that keeps inquiry open.

Characteristic operations:

• Begin immanently: Take a concept or form of consciousness on the terms it gives itself.
• Follow its commitments: Work out what the form must include or exclude.
• Expose self-undermining: Show where those commitments contradict or destabilize the original determination.
• Preserve and transform: Develop a richer determination that retains what the earlier form established while overcoming its limit.

Characteristic operations:

• Take up the thesis: Begin from the opponent's stated claim and commitments.
• Trace its consequences: Apply the claim consistently to the case under examination.
• Show the difficulty: Reveal contradiction, circularity, regress, or another consequence the thesis cannot sustain.
• Withhold a reified alternative: Avoid turning the critique into another claim about an intrinsically existing reality.

Characteristic operations:

• Formulate both sides: Consider a claim and a genuinely conflicting alternative.
• Set out the opposition: Gather appearances and arguments that bear on each side.
• Assess their force: Determine whether either account is more convincing than the other.
• Suspend assent: When the considerations remain equipollent, affirm neither conclusion and continue investigating.

Characteristic operations:

• State the question: Formulate a precise issue that admits opposed answers.
• Present objections: Give serious arguments against the position to be defended.
• Set out relevant authority: Record a contrary consideration from an accepted text or thinker where appropriate.
• Determine the question: Offer the central argument for the answer.
• Reply in order: Return to each objection and show why it does not overturn the determination.

Characteristic operations:

• Elicit a claim: Ask the interlocutor to state a definition or belief they endorse.
• Secure related commitments: Use questions to establish further premises the interlocutor accepts.
• Derive a conflict: Show that those commitments contradict the original claim or one another.
• Revise and continue: Withdraw or refine the failed proposal and test the new account.

Characteristic operations:

• Select the target: Identify the claims or inferential structure that the representation must preserve.
• Choose a formal language: Use a logical or mathematical system expressive enough for the relevant distinctions.
• Translate explicitly: Represent the premises, conclusion, operators, and assumptions in that system.
• Test the representation: Derive consequences, search for countermodels, or check consistency and validity.
• Compare and revise: Return to the original argument to see whether the formal result depends on a disputed translation.

Characteristic operations:

• State the starting points: Define the basic terms and set out the axioms on which later claims depend.
• Derive propositions in order: Demonstrate each claim from the definitions, axioms, and propositions already established.
• Expose dependencies: Make it possible to locate the premise on which a disputed conclusion rests.

Characteristic operations:

• Identify the terms: Distinguish the major, minor, and middle terms in the inference.
• Standardize the propositions: Express the premises and conclusion in categorical form.
• Determine figure and mood: Record the position of the middle term and the quantity and quality of each proposition.
• Test validity: Decide whether the form makes the conclusion follow necessarily from the premises.

Characteristic operations:

• Frame an experience-sensitive claim: Identify what observation or experience could bear on the issue.
• Gather evidence: Attend to perception, reflection, records, or relevant findings.
• Compare claim and evidence: Ask what the evidence supports, underdetermines, or conflicts with.
• Revise and repeat: Modify the claim or inquiry in response to what is observed.

Characteristic operations:

• State the theory so it forbids something: Formulate the claim precisely enough that some observable outcome is ruled out.
• Derive a risky prediction: Identify an outcome the theory requires but that is improbable on background knowledge alone, so the theory is exposed if it is wrong.
• Seek the refuting observation: Design the severest test available rather than collecting agreeable examples.
• Corroborate or abandon: Treat survival as provisional standing, and treat a refutation as grounds to revise or drop the theory rather than to rescue it with an ad hoc amendment.

Characteristic operations:

• Study particulars: Attend to concrete things, texts, relationships, and events instead of seeking principle through detached abstraction alone.
• Discern patterns: Identify the structures and tendencies that distinguish one thing or situation from another.
• Extend by comparison: Accumulate observations and connect their patterns through association, analogy, and generalization.
• Refine response: Use the resulting discernment to judge unfamiliar situations with greater fairness and appropriateness.

Characteristic operations:

• Define the phenomena: Begin with an observable field rather than a speculative account of hidden essences or final causes.
• Match technique to subject: Use observation, experiment, or comparison according to what the relevant science can assess.
• Formulate laws: Identify stable relations among phenomena instead of treating description as a list of isolated facts.
• Connect prediction and action: Use established regularities to anticipate phenomena and guide practical intervention.

Characteristic operations:

• Begin from real doubt: Identify a disrupted expectation or unsettled problem that calls for inquiry.
• Trace practical bearings: Ask what experiential differences accepting the claim would make.
• Test through consequences: Compare those expectations with action, observation, and further argument.
• Revise communally: Keep the result open to correction by later inquiry and other investigators.

Characteristic operations:

• Reverse habitual analysis: Notice how practical intelligence divides a moving reality into fixed concepts and external viewpoints.
• Enter duration: Attend sympathetically to experience as a continuous, qualitative movement rather than as a sequence of separate states.
• Extend the starting experience: Follow the differences and tensions within duration instead of treating the first introspective moment as the whole.
• Return to conceptual mixtures: Use the distinctions disclosed by intuition to reconsider the composites that ordinary analysis presents as basic.

Characteristic operations:

• Turn attention inward: Direct awareness to a mental state one is in, or has just been in.
• Report the state: Classify what is found — a sensation, an image, a thought, an emotion.
• Separate observation from theory: Distinguish what is noticed from the account one already holds of the mind.
• Weigh the report's reliability: Treat introspective evidence as defeasible, since attending to a state can alter or misclassify it.

Characteristic operations:

• Identify the natural attitude: Notice the ordinary commitment that the world simply exists as taken for granted.
• Perform the epoché: Suspend use of that commitment without denying the world's existence.
• Redirect attention: Examine the intentional relation between experience and what appears in it.
• Describe structures: Articulate recurring features of givenness without immediately reducing them to external causes.
• Vary the example freely: Change an example's features in imagination until the features it cannot lose without ceasing to be that kind of thing stand out — Husserl's eidetic variation, an operation inside this method rather than a separate one, used to seek essences.

Characteristic operations:

• Attend to the body: Observe breathing, posture, activity, and bodily processes as bodily processes.
• Attend to feeling: Notice pleasant, unpleasant, and neutral feeling without immediately grasping or resisting it.
• Attend to mind: Recognize the presence or absence of states such as desire, aversion, distraction, and concentration.
• Attend to phenomena: Examine recurring patterns and teachings that organize experience and liberation.

Characteristic operations:

• Submit to the forms: Take up established ritual practice before one fully understands or endorses it.
• Attend while performing: Bring genuine feeling to the form, since hollow performance cultivates nothing.
• Extend by analogy: Carry the disposition trained in ritual into situations the forms do not cover.
• Refine over a lifetime: Treat cultivation as continuous, with study and correction alongside practice.

Characteristic operations:

• Notice the impression: Register the appearance before treating it as a settled fact or value.
• State its judgment: Make explicit what the impression says is good, bad, threatening, or necessary.
• Test control and reason: Ask what depends on one's agency and whether the judgment survives examination.
• Give or withhold assent: Accept, revise, or reject the impression's claim before acting on it.

Characteristic operations:

• Receive the case: Take up a specific recorded exchange assigned by a teacher.
• Hold it continuously: Keep the case present in and out of formal sitting, rather than solving it in one attempt.
• Exhaust conceptual escape: Let ordinary explanatory strategies fail instead of settling for a satisfying interpretation.
• Answer and be tested: Present a response in interview, where a teacher judges whether it comes from understanding.

Characteristic operations:

• Receive the teaching: Begin from an Upaniṣadic instruction learned through study and guidance.
• Resolve conceptual doubt: Use reflection and reasoning to clarify what the instruction means.
• Contemplate steadily: Return sustained attention to the teaching and its bearing on self-understanding.
• Assimilate the insight: Work against habitual identification until understanding becomes stable and transformative.

Characteristic operations:

• Choose a stable object: Settle on one support for attention, such as the breath.
• Return without agitation: Notice wandering and come back, repeatedly and without force.
• Calm the disturbance: Let restlessness, craving, and aversion subside rather than suppressing them.
• Stabilize into collectedness: Allow attention to rest continuously, producing the composure that sustained observation requires.

Characteristic operations:

• Settle into stillness: Withdraw from ordinary projects and reactive activity.
• Release bodily fixation: Let attachment to bodily form and status recede.
• Let discriminating knowledge fall away: Stop imposing fixed divisions and evaluations on experience.
• Remain open to transformation: Allow responsive activity to arise without forced control.

Characteristic operations:

• Hear the teaching: Receive an Upaniṣadic instruction through study or guidance.
• Reflect on it: Use reasoning to clarify its meaning and answer conceptual doubt.
• Contemplate it: Sustain attention to the teaching beyond discursive restatement.
• Test assimilation: Examine whether the understanding changes how self and world are apprehended.

Characteristic operations:

• Establish attentive observation: Select bodily or mental processes as the field of examination.
• Track change: Notice arising, alteration, and passing rather than treating experience as static.
• Examine appropriation: Observe how processes are taken as “I” or “mine” and how craving follows.
• Cultivate insight: Understand impermanence, unsatisfactoriness, and non-self through trained observation.

Characteristic operations:

• Restrain mental turning: Work to quiet the fluctuations of ordinary mental activity.
• Fix attention: Bind awareness to one chosen object, holding it in place.
• Sustain unbroken flow: Let fixed attention lengthen into continuous, uninterrupted attending.
• Enter absorption: Allow the distinction between attending and object to fall away, yielding discriminative insight.

Characteristic operations:

• Adjust the body: Take a stable seated posture suited to sustained practice.
• Adjust the breathing: Let breathing become settled and attend to it as the lineage instructs.
• Adjust the mind: Work with distraction through breath, kōan, or just-sitting practice.
• Return through practice: Carry the less dualistic mode of attention into ordinary activity.

Characteristic operations:

• Locate a governing opposition: Identify paired terms whose hierarchy organizes the text.
• Follow the dependence: Show how the privileged term relies on what it excludes or subordinates.
• Read tensions closely: Track passages where the text's operation works against its explicit claim.
• Displace the hierarchy: Recast the opposition without treating a simple reversal as the final result.

Characteristic operations:

• Select a present practice: Begin with a value, institution, identity, or category that now appears settled.
• Reject a single pure origin: Look for heterogeneous beginnings, accidents, conflicts, and reversals.
• Trace embodied practices: Examine the institutions, disciplines, and techniques through which the object took shape.
• Diagnose present stakes: Show how that history still organizes what can be thought, done, or contested.

Characteristic operations:

• Form a provisional whole: Begin with an initial sense of the work, context, or question.
• Interpret a part: Read a passage or feature in light of that provisional whole.
• Let the part revise the whole: Change the larger interpretation when the detail resists it.
• Repeat reflectively: Continue the movement while examining the historical assumptions brought by the interpreter.

Characteristic operations:

• Locate material organization: Examine how production, labor, and property are arranged.
• Map social relations: Identify the classes, institutions, and dependencies formed through that organization.
• Historicize ideas and institutions: Ask how dominant concepts and practices arise from changing social conditions.
• Test mystification: Show where an account hides or naturalizes the relations that sustain it.

Characteristic operations:

• Identify the representation: Select a widespread belief, image, norm, or category with social force.
• Test its account of reality: Examine what the representation reveals, hides, or treats as natural.
• Trace its social production: Relate the belief to institutions, practices, interests, and asymmetries of power.
• Assess its effects: Ask how it supports or contests domination and what emancipation would require.

Characteristic operations:

• Reconstruct the operative standard: Establish the norm the object actually relies on to justify itself, which is not always the one it advertises.
• Grant that standard: Argue from it rather than substituting one the critic prefers, so the criticism cannot be answered by rejecting the critic's values.
• Show the failure is structural: Demonstrate that the object generates the shortfall itself, rather than merely happening to fall short of it.
• Read the contradiction as a direction: Take what the object cannot deliver as an indication of the form that could, instead of stopping at the negative result.

Characteristic operations:

• Define the system: Specify the field of signs, practices, roles, or objects under study.
• Map relations: Identify contrasts, positions, transformations, and rules within that field.
• Test the structure: Compare cases to see whether the proposed relations explain their differences.
• Explain the element relationally: Show what the item is by the position and function it has in the system.

Characteristic operations:

• Establish the text: Settle wording, translation, and the unit being expounded before interpreting it.
• Read in context: Weigh the passage against its immediate setting, the wider work, and the tradition of commentary.
• Resolve difficulty: Where a plain reading conflicts with other commitments, argue for a figurative, analogical, or restricted sense.
• Defend the reading: Present the interpretation as a claim answerable to the text rather than as private insight.