The Mind-Body Problem
Some Theories of Mind
• Dualism
– Substance Dualism: mind and body are differerent substances.
Mind is unextended and not subject to physical laws.
• Interactionism: mind and body interact
• Occasionalism/Parallelism: mind and body don’t interact
– Property/Event Dualism
• Epiphenomenalism: physical events cause mental events
but mental events don’t cause anything (may not be a
substance theory)
• Property Dualism:(some) mental states are irreducibly nonphysical attributes of physical substances
Some Theories of Mind
• Physicalism: mental states are identical to physical states, in
particular, brain states or, minimally, supervene upon physical
states.
– (“Analytical” or “Logical”) Behaviorism: talk about mental
states should be analyzed as talk about behavior and behavioral
dispositions
– The Identity Theory (Type-Physicalism): mental states are
identical to (so nothing more than) brain states
– Functionalism: mental states are to be characterized in terms of
their causal relations to sensory inputs, behavioral outputs and
other mental states, that is, in terms of their functional role.
Dualism(s)
Pro
Con
• Qualia
• Causal closure of the physical
• Irreducibility of psychology
• Simplicity
• The Zombie Argument
• The Cartesian Essentialist
Argument
Descartes’ Arguments for Dualism
• Empirical Argument
– The complexity and flexibility of human behavior, including
linguistic behavior, couldn’t be achieved by mere mechanism so
we need to assume some non-physical substance as an
explanation for such behavior.
• Essentialist Argument
– It is conceivable that one’s mind might exist without one’s body
– Whatever is conceivable is logically possible
– Therefore, it is possible one’s mind might exist without one’s
body
– Therefore one’s mind is a different entity from one’s body
The Zombie Argument
• A (philosophical) zombie is a being which is a perfect duplicate of a
normal human being—including brain and neural activity—but which
is not conscious.
• The Zombie Argument for property dualism
– Zombies are conceivable
– Whatever is conceivable is logically possible
– (Some) mental states/properties/events are not identical to any
brain states/properties/events
• Note: this argument doesn’t purport to establish substance dualism
or, as Descartes wished to show, that minds/persons could exist in a
disembodied state.
Problem with Cartesian Dualism
• “We do not need that hypothesis”: complex behavior can be
explained without recourse to irreducibly non-physical states.
– Contra Descartes, purely physical mechanisms can exhibit the
kind of complex, flexible behavior, including learning (or
“learning”) characteristic of humans.
• All physical events have sufficient causes that are themselves
physical events
– Physicalism is an aggressor hypothesis: we explain more and
more without recourse to non-physical events/states
– Agency explanations are eliminated in favor of mechanistic
explanations—including explanations for agency itself.
– Claims to the effect that non-physical events cause physical
events introduces an even bigger mystery: what is the
mechanism?
Epiphenomenalism
• Motivation for Epiphenomenalism
– All physical events have sufficient causes that are themselves
physical events
– But some mental events—qualitative states, the what-it-is-like
experience—seem to be irreducibly nonphysical: it seems
implausible to identify them with brain events.
• Problem: intuitively some mental states cause behavior
– E. g. pain causes people to wince
– Moreover, part of what we mean by “pain” seems to involve an
association* of with characteristic behavior
*We’ll leave “association” intentionally vague
(Philosophical) Behaviorism
• Motivation
– We want to hold that there are no irreducibly non-physical
causes of physical events
– But we also need to accommodate the fact that what we mean
by terms designating mental states involves an association with
characteristic behavior.
• Problems
– Intuitively, there’s more to some mental states: the problem of
qualia
– Intuitively, there can be less to mental states: it’s conceivable
that one may be in a given state without even being disposed to
characteristic behavior—or that one may be disposed to
uncharacteristic behavior
– Dispositions aren’t causes so, while behaviorism associates
mental states with behavior, they still don’t cause behavior.
The Identity Theory
• Motivation
– We want to hold that there are no irreducibly non-physical
causes of physical events
– But we also want to understand them as “inner states” that are
causally responsible for behavior
• Problems
– Qualia again: intuitively there is more to consciousness than
brain states
– Species chauvinism: if we identify a type of mental state, e.g.
pain, with a type of brain state that is responsible for pain in
humans, e.g. the firing of C-fibers, what do we do about nonhumans who don’t have the same kind of brain states but who,
we believe, can never the less have the same kind of mental
states?
What a theory of mind should do
• Make sense of consciousness: “The Hard Problem”
• Avoid commitment to irreducibly non-physical states, events or
substances
• Explain the causal role of mental states as
– Effects of physical events
– Causes of behavior
– Causes of other mental events
• Allow for multiple realizability in order to avoid species
chauvinism
– We want to be able to ascribe the same kinds of mental states
we have to humans who may be wired differently, other animals
and, possibly to beings that don’t have brains at all, e.g.
Martians, computers
Functionalism
• What makes something a mental state of a particular type does not
depend on its internal constitution, but rather on the way it
functions, or the role it plays, in the system of which it is a part.
• Topic Neutrality: mental state concepts don’t specify their intrinsic
character, whether physical or non-physical—that’s a matter for
empirical investigation.
– So Functionalism is in principle compatible with both physicalism
and dualism
• Multiple Realizability: A single mental kind (property, state, event)
can be "realized" by many distinct physical kinds.
– The same type of mental state could, in principle, be “realized”
by different physical (or non-physical) states
– Disagreement about how “liberal” we should be in this regard
An Example: Pain
• We’re interested in analyzing or ordinary concept of pain
• We understand it in terms of its causal role
– As being typically produced by certain stimuli, e.g. bodily injury
– As tending to produce certain behavior, e.g. wincing
– As producing further mental states, e.g. resolving to avoid those
stimuli in the future
• We recognize that different kinds of physical (of non-physical)
mechanisms may play that role
– Compare to other functional concepts like “can opener”
– We leave empirical questions to empirical investigation
The Big Questions About Functionalism
• Consciousness: some mental states appear to have intrinsic,
introspectable features—and those features seem to be essential
– Inverted Qualia (see Block “Inverted Earth”)
– Zombies
– The Knowledge Argument (see Jackson “What Mary Didn’t
Know”)
• Understanding: controversial whether understanding can be
reduced to the ability to mediate input and output by manipulating
symbols (see Turing “Computing Machinery and Intelligence” vs.
Searle on The Chinese Room
• Some sly questions: Can the program of analysis be plausibly
carried through? Compare to the problem of carrying through the
phenomenalist program. And, if so, could we be stuck with species
chauvinism again?