The Mind-Body Problem:
Summary:
The “mind-body problem”
refers to the difficulty of
explaining how the mental
activities of human beings
relate to their living
physical organisms.
Historically, the most commonly accepted solutions have included mind-body dualism (Descartes),
reductive materialism (Hobbes) or idealism (Berkeley), and the double aspect theory (Spinoza).
This problem has been a major concern of metaphysicians in “modern” times (i.e. since the 17th century):
 arose as a result of certain views of Descartes
 increasing knowledge about both mental and physical worlds has not answered it
 addresses the questions: “What is the fundamental nature of the mind and the body?”
and “How are the mind and the body related?”
 Elementary observation of mental and physical events might lead to the suspicion that
they are quite different; yet, they seem to be in some relation or have some influence on
each other; how do we explain this?
 i.e. our scientific knowledge would seem to suggest that the physical world is
inanimate, without purpose, and yet “determined” or fixed; it operates
according to the laws of science
 the mental world, by contrast, operates through consciousness, planning,
desire, intention, etc.
 though these worlds may seem to be quite different, experience indicates
that they are interrelated or connected – when something happens in the
physical world, this may change one’s thoughts or feelings in the mental
world; similarly, a desire for light may cause one to strike a match in the
physical world
Descartes’ Mind-Body Theory:


often blamed for the difficulties that arose from this problem
o asserted that mind and body are 2 totally different types of being; they are different
substances
o from the “clear and distinct” idea that he had in his own mind, he decided that
 the basic feature of matter was its geometrical qualities (size, shape, etc.)
 the basic feature of mind was thinking
 according to Descartes, the essential property of a mind is that it
thinks, and the essential property of a body is that it is “extended” (in
space)
Descartes further asserted that “mind” is never extended, and that “body” never thinks; in other
words, the 2 realms of thought and extension are completely different
o He went on to insist that all physical
action occurs by the impact of one
“extended object” upon another; since
mental events are (by definition) NOT
extended, how can there be any impact
or contact between that whose nature it
is to exist in space, and that which does
not occur in space?
 How can an idea move a hammer,
or a hammer strike upon an idea?
 Descartes was nevertheless impressed by the
scientific (and common-sense) evidence that
mind and body do affect each other
o A pin jabbed into the physical, “extended” finger is followed by a thought of pain in the
“unextended” mind
o Examining the evidence closely, he concluded that the mind is only aware of physical
events in the brain
 Various motions can take place in the body without being followed by mental
events, unless the physical motions first cause movements in the nervous system
and then in the brain
 e.g. breathing, digestion
 Similarly, one can stimulate thoughts without affecting the body, just by producing
certain physical motions in the brain
 e.g. the phenomenon of “ghost” limbs
o All this led him to conclude there must be some point of contact between the mental and
physical worlds, and that the contact must take place in the brain
 He believed this junction was found in the pineal gland at the base of the brain
 This belief doesn’t really answer the question how the mind and body interact in the
pineal gland
 He became increasingly vague about the matter, and eventually said that,
since we all experience the connection as fact, the question was best
answered by not thinking about it, and just accepting it as one of those
mysteries that can’t be comprehended
The Materialist Theory:

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others weren’t prepared to give up so easily, and identified
the initial separation of mind and body in Descartes’
thoughts as the key problem
o if one refuses to grant that mind and body are 2
different kinds of being, one should have no trouble
accounting for their interaction
one way of avoiding Descartes’ pitfall is to adopt a
completely materialist metaphysics and claim that both
mental and physical events can be explained purely in terms
of physical concepts and laws
o Thomas Hobbes was the key advocate of this
approach in Descartes’ day; some behavioural
psychologists hold it today
o The key idea is that what we call mental events are
really (like physical events) only combinations of matter in motion
The physical movements that occur in the brain are what we call thoughts, and these
are produced by other events in the physical world, whether outside or bodies or
within, and can in turn produce further physical motions in ourselves or outside
ourselves
 Every idea is nothing but a set of physical occurrences in our higher nervous
system and brain
this has the advantage of being very simple
o there is also a vast body of scientific evidence (psychology, psychiatry, physiology) about
the physical basis of many mental events that makes it seem plausible
 e.g. treatments for depression, “brainwashing,” etc.
 work on “artificial intelligence” also suggests there may be some merit in this
there are, however, some criticisms:
o I am aware of sensations, emotions, thoughts – not physical occurrences in my brain; even
if the latter cause the former, it still remains the case that they are different and
distinguishable: hence, the mental world can’t be reduced merely to physical events
o If mental events are all there is to it, how do you explain truth and error? How do you
distinguish them, if they reduce merely to a series of physical events in someone’s brain?
o I am forced into a determinist world view, with no room for free choice

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Further Thoughts on Mind-Body Dualism: (see text pp. 141-45)
Descartes’ insistence that mind and body are 2 essentially different substances (“Substance Dualism”)
leads to a problem that can be diagrammed like this:
Subject
(mental)
Perception
Object
(physical)
What happens here?
How does one substance perceive
a “completely different” kind of substance?
Philosophers have (as usual) tended toward one extreme or the other, depending on which sort of
skepticism they embrace:
1. Idealists (e.g. Descartes, Berkeley) are skeptical about whether we can trust that our perceptions
fit reality, or whether there actually IS any reality outside our minds at all. Idealists think that the
mental is all there is. This is a kind of solipsism: i.e. things have no independent existence outside
of my thoughts about them. (“Subjectivism”). Descartes further believed that mind and matter are
two completely different kinds of thing (“Substance Dualism”).
2. Materialists (e.g. Locke, Hobbes) are skeptical about whether the “mental” is anything other than
the result of purely physical events in our brain. Materialists think that matter is all there is
(“Monism”). This leads to determinism: i.e. there is no freedom; the world unfolds in a purely
material/mechanical way. (includes “identity theorists,” “eliminative materialists,” and
“functionalists”)
Some philosophers have gone through extraordinary gymnastics to try to bring these extremes closer
together.

Epiphenominalists modify materialism and admit that our mental perceptions are more than
physical states in our brain. However, they still judge them to be mere by-products of those
physical states, as smoke is a by-product of fire. This still does not do our mental life justice.
(“Identity theorists”)

Occasionalists argue that, since the mental and physical can’t interact, what must happen is
that, for each event in one realm, GOD makes a corresponding event occur in the other. The one
event doesn’t cause the other; it is merely the occasion of God’s action. This still doesn’t answer
the question of how the mental interacts with the physical (God takes the place of Descartes’
pineal gland), and makes for a “busy-every-minute” God who doesn’t have much in common
with most conceptions of God.

Monadists (e.g. Leibnitz) argue that everything, whether mental or physical, is independent
and constitutes a monad whose actions are wholly determined by its nature, and not by its
interactions with other monads. Monads only appear to interact in relationship because they
have all been created by God in a “pre-established harmony,” so that, without influencing each
other, events in each one nevertheless occur harmoniously with all of the others. While this gets
around the problem of dualism, it is simply … incredible.

Dual-aspect theorists (Spinoza – “the Monist’s solution”) reject dualism, and argue that the
mental and physical are in fact “flip sides of a coin;” i.e. mind and body are both aspects of one
and the same being. Therefore, whenever there is an event in one realm, there must be a
parallel event in the other, since the mental and physical are just different ways of looking at
the same thing. However, Spinoza identified the mental with God and the physical with nature;
by arguing the two are just different aspects of the same thing, he in effect argued that nature is
God (i.e. pantheism), which most philosophers and theologians find unacceptable.