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Intro to Philosophy Unit 4: Mind and Body

The mind-body problem asks how mental life, such as thoughts, feelings and experiences, relates to the physical brain and body. This unit compares dualism, behaviorism, identity theory and functionalism, and the puzzles of consciousness and personal identity.

Covers: Substance dualism and its arguments, The interaction problem, Behaviorism and identity theory, Functionalism and multiple realizability, Artificial intelligence: Turing test and Chinese Room, Consciousness and qualia, Personal identity

Study guide

René Descartes defended substance dualism: the mind is a thinking, unextended substance and the body an extended, unthinking one. He argued that he could clearly conceive his mind existing without his body, so they must be distinct, and that bodies are divisible while minds are not, so by Leibniz's law they differ. Dualism respects the sense that experience is unlike anything physical, but it faces the interaction problem raised by Princess Elisabeth of Bohemia: how can an unextended mind push a body? Responses include property dualism, which keeps one substance with both physical and mental properties, and epiphenomenalism, which says mental events are caused by the brain but cause nothing.

In the twentieth century many philosophers turned to physicalism, the view that everything is physical. Gilbert Ryle mocked dualism as 'the ghost in the machine' and a category mistake, and logical behaviorists analyzed mental states as dispositions to behave. Behaviorism struggles with cases where feelings and behavior come apart, such as an actor faking pain. Identity theorists, including U. T. Place and J. J. C. Smart, held that mental states are brain states, as lightning turned out to be electrical discharge. Hilary Putnam objected with multiple realizability: octopuses, humans and perhaps robots could all feel pain with very different hardware, so pain cannot be one specific brain state.

Functionalism answers that a mental state is defined by its causal role: what causes it, how it interacts with other states and what behavior it produces. Like software running on different machines, the same mental state can be realized in different physical systems. Functionalism inspired artificial intelligence research. Alan Turing proposed that a machine counts as intelligent if its conversation cannot be told apart from a human's. John Searle's Chinese Room replies that a person could follow rules to produce perfect Chinese answers without understanding a word, so symbol manipulation (syntax) is not understanding (semantics). Ned Block's China Brain asks whether a nation simulating neurons would feel anything.

The deepest challenge is consciousness. Thomas Nagel argued that there is something it is like to be a bat that objective science seems unable to capture. Frank Jackson's Mary knows all physical facts about color but learns something when she first sees red, suggesting physical facts leave out qualia. David Chalmers calls explaining why physical processes are accompanied by experience the hard problem, and imagines zombies physically like us without experience. Physicalists reply in various ways, such as the ability hypothesis or Dennett's denial that there is a separate hard problem. A related question is personal identity: Locke held that you are the same person as someone in the past if you remember their experiences, while Thomas Reid objected that memory connections are not transitive.

Key ideas

• Substance dualism holds that mind and body are different substances but must explain how they interact.
• Behaviorism analyzes mental states as behavior or dispositions, but feelings and behavior can come apart.
• Identity theory equates mental state types with brain state types and is challenged by multiple realizability.
• Functionalism defines mental states by causal role, so different physical systems can share them.
• The Chinese Room argues that running a program is not enough for understanding.
• Mary's Room, zombies and Nagel's bat argue that physical facts may not capture conscious experience.
• Locke's memory theory of personal identity faces Reid's transitivity objection.

Formulas and rules

Common mistakes

• Confusing functionalism with behaviorism; functionalism includes inner states and their relations, not just behavior.
• Saying the Chinese Room shows computers cannot pass the Turing test; Searle grants they might and denies that this proves understanding.
• Treating epiphenomenalism as denying that the brain causes mental states; it denies only that mental states cause anything.
• Thinking multiple realizability supports identity theory, when it is the main argument against it.
• Assuming Mary's Room concludes color is unreal; it concludes physical facts may not be all the facts.

Before the test, make sure you can

• Explain Descartes' arguments for substance dualism and the interaction problem.
• Describe behaviorism and identity theory and an objection to each.
• Explain functionalism and the multiple realizability argument.
• Summarize the Turing test and Searle's Chinese Room, including the systems reply.
• Explain Mary's Room, zombies and Nagel's bat as challenges to physicalism.
• Match each theory of mind with its classic problem.
• Apply Locke's memory theory to a puzzle case and state Reid's objection.

Words to know

Substance dualism

The view that mind and body are two distinct substances, defended by Descartes.

Interaction problem

The problem of how a nonphysical mind could cause changes in a physical body, and vice versa.

Property dualism

The view that there is one kind of substance with both physical and irreducibly mental properties.

Epiphenomenalism

The view that mental events are caused by physical events but have no causal effects.

Category mistake

Ryle's term for treating something as belonging to the wrong logical type, as in 'the ghost in the machine.'

Logical behaviorism

The view that statements about the mind are statements about behavior or dispositions to behave.

Identity theory

The view that mental state types are identical to brain state types.

Multiple realizability

The idea that the same mental state can be realized by different physical systems.

Functionalism

The view that mental states are defined by their causal roles.

Eliminative materialism

The view that folk-psychological concepts like belief may be false and replaced by neuroscience.

Turing test

A test in which a machine counts as intelligent if its conversation is indistinguishable from a human's.

Chinese Room

Searle's thought experiment arguing that symbol manipulation alone does not produce understanding.

Qualia

The subjective, felt qualities of experience.

Knowledge argument

Jackson's Mary's Room argument that physical knowledge does not include all facts about experience.

Hard problem of consciousness

Chalmers' term for explaining why physical processes are accompanied by subjective experience.

Philosophical zombie

A hypothetical being physically identical to a human but with no conscious experience.

Memory theory of personal identity

Locke's view that a person is the same over time as far as memory and consciousness reach.

Sample practice questions

30 more questions like these, from level 1 to 5, are in the practice set.