Questions: Multiple Realizability

Question 1

Multiple realizability is most directly an argument against which view?

• A. Dualism, because it shows minds are not separate from bodies
• B. Type identity theory, because it shows there is no one-to-one mapping between mental types and physical types
• C. Functionalism, because it shows mental states depend on physical substrate
• D. Epiphenomenalism, because it shows mental states are causally efficacious

Answer: (B)

Type identity theory holds that each mental state type (e.g., pain) is identical to a specific neural state type. Multiple realizability shows that pain can be realized by very different physical structures across species — so there is no single physical type to identify pain with. Functionalism is actually supported by multiple realizability, not undermined by it.

Question 2

Multiple realizability shows that mental states are non-physical entities, since they can seldom be identified with any particular physical type.

• T. True
• F. False

Answer: False

This is the key misconception. Multiple realizability only shows that mental states are not type-identical to specific neural types. Each instance of pain is still physically realized — it just may be realized by different physical tokens in different creatures. The conclusion is anti-reductionist about types, not anti-physicalist about tokens.

Question 3

How does multiple realizability support functionalism as a theory of mind?

Model answer: Functionalism identifies mental states by their causal-functional roles — their relationships to inputs, outputs, and other mental states — rather than by their physical substrate. Multiple realizability shows that the same functional role can be filled by very different physical materials, which is exactly what functionalism predicts. This makes functionalism more plausible than identity theory, which requires a single physical type for each mental type.

If pain is defined by its functional role (caused by tissue damage, causes distress and avoidance behavior), then any system that plays that role is in pain, regardless of what it's made of. This is why multiple realizability was so important for functionalism: it showed that what matters for having a mind is the organization of states and processes, not the particular material.