Physicalist theories of mind
Most contemporary philosophers think the mind is physical in some sense. They disagree sharply about what that means.
Behaviorism and identity theory
Behaviorists claimed that talk of mental states is really talk of behavior or dispositions to behave: being thirsty just is being disposed to seek water. Critics noted that someone can feel pain and hide it. Identity theorists instead said mental states are brain states, so pain simply is a certain pattern of neural activity, much as lightning is electrical discharge.
Functionalism
Functionalism defines a mental state by what it does: its typical causes, effects, and links to other mental states. Pain is whatever state is caused by damage, causes distress, and prompts avoidance. Because the same role could be filled by neurons, silicon chips, or alien biology, functionalism allows minds to be realised in many physical systems.
Worked example: multiple realizability
Suppose an octopus, with a very different nervous system from ours, recoils from a hot surface and afterwards avoids it. If pain were identical to one human brain state, the octopus could not be in pain. A functionalist says it can, because its state plays the same role. This argument helped move many philosophers from identity theory toward functionalism.
Flashcard
Mental states are identical to brain states
Check your understanding
Which theory most easily allows that a well-designed robot could have beliefs?