Type Identity Theory

Classification

Position level

specific

Domains

Philosophy of Mind

Overview

Type identity theory holds that each kind of mental state is one kind of brain process: pain, say, is a particular kind of neural activity, as lightning is an electrical discharge. U. T. Place (1956) and J. J. C. Smart (1959) insisted that this is an empirical discovery, not a matter of meaning. "Pain" does not mean "brain process", just as "lightning" does not mean "electrical discharge", yet in each case the two turn out to be one thing. The appeal is economy: Smart found it unbelievable that sensations alone should stand outside the physical account of everything else.

The standard objection comes from Functionalism. If pain is one kind of human brain process, a creature without that process cannot be in pain, yet octopuses, and perhaps machines, seem able to feel it while being built very differently. Identity theorists have replied by limiting each identity to one kind of creature, so that pain in humans is one brain process and pain in octopuses another.

Position on

• What Are Mental States?

Broader position

• Materialism

Rival positions

• Functionalism

  Question scope: What Are Mental States?

References

• U. T. Place, 'Is Consciousness a Brain Process?', British Journal of Psychology 47 (1956), pp. 44–50
• J. J. C. Smart, 'Sensations and Brain Processes', Philosophical Review 68 (1959), pp. 141–156
• Stanford Encyclopedia of Philosophy, Multiple Realizability, §1.2 (the argument from creatures that seem able to feel pain) and §2.2 'Domain-Specific Identities and Reductions'
• Stanford Encyclopedia of Philosophy, The Mind/Brain Identity Theory, opening paragraph (states and processes of the mind are identical to states and processes of the brain) and §6 'Type and Token Identity Theories'
• Stanford Encyclopedia of Philosophy, The Mind/Brain Identity Theory, §1 (identity theorists often describe themselves as 'materialists', though 'physicalists' may be a better word) and §4 (Armstrong preferred to describe the identity theory as 'Central State Materialism')