Chapter 2
The Mind-Body Problem
Bodies and Minds
• Modern science has shown that what goes on
in our bodies can be explained in physical
terms, as the result of various electrochemical
or biomechanical interactions.
• But what about what goes on in our minds?
Can our thoughts be explained physically?
Thought Experiment: Descartes’s Mechanical
Moron
• Can we construct a machine that thinks?
• Descartes claims that no machine would be
able to use language or solve problems like we
do.
• Do you agree? Why or why not?
Thought Experiment: Leibniz’s
Mental Mill
• Suppose that we created
a machine that thinks,
and suppose further that
we were able to walk
around inside the
machine.
• Leibniz claims that
explaining the working of
the parts of the machine
would not explain its
thinking.
Thought Probe: Walking Around
Inside the Brain
• Suppose you were able to walk
around inside a brain, like the
crew from the movie Fantastic
Voyage.
• Would you observe thinking?
Theories of Reality
• Idealism: the doctrine that all that exists are
minds and their contents.
• Materialism: the doctrine that all that exists
are material objects.
• Dualism: the doctrine that reality contains
both mental and material things.
Section 2.1
The Ghost in the Machine
Mind as Soul
Cartesian Dualism
• Cartesian dualism is the doctrine that mental
states are states of an immaterial substance
that interacts with the body.
Descartes’s Doubt
• We know something only if it’s certain.
• Most of what we think we know is based on
sense experience.
• But we can’t be certain of anything we’ve
learned through sense experience.
Thought Experiment: Descartes’s Dream
Argument
• “How often has it happened to me that in the
night I dreamt that I found myself in this
particular place…while in reality I was lying
undressed in bed.”
• Can you be certain that you’re not dreaming
right now? If so, how?
Thought Experiment: Descartes’s Evil
Demon
• “How do I know that [an evil demon] has not
brought it to pass that there is no earth, no
heaven, no extended body, no magnitude, no
place, and that nevertheless they seem to me
to exist just exactly as I now see them?”
• Can you be certain that there is no such
demon?
“I think, therefore I am”
• Descartes cannot doubt that he is thinking, for
doubting is a type of thinking.
• And Descartes can’t doubt anything unless he
exists.
• So Descartes claims that he can be absolutely
certain of one thing, namely, “I think,
therefore I am.”
The Conceivability Argument
1. It’s conceivable for me to exist without having a
body.
2. Whatever is conceivable is possible.
3. Therefore, it’s possible for me to exist and not
have a body.
4. If it’s possible for me to exist without having a
body, then having a body is not essential to me.
5. Therefore, having a body is not essential to me.
The Conceivability Argument
6. It’s inconceivable for me to exist without having a
mind.
7. Whatever is inconceivable is impossible.
8. Therefore, it’s impossible for me to exist and not
have a mind.
9. If it’s impossible for me to exist without having a
mind, then having a mind is essential to me.
10. Therefore, having a mind is essential to me.
Cartesian Dualism
• Descartes has proven that he is a thing that
thinks.
• But physical things, he claims, cannot think.
• So, he concludes, he (his mind) is a nonphysical thing.
Thought Probe:
Animal Soul
• Descartes believed that only humans had
souls because, among other things, only
humans have free will.
• Do you agree? Do animals have souls?
Indiscernibility of Identicals
• The indiscernibility of identicals is the
principle that if two things are identical,
then they must both possess the same
properties.
• For example, if Mark Twain is identical to
Samuel Clemens, then whatever is true of
Mark Twain is true of Samuel Clemens
and vice-versa.
The Divisibility Argument
1. If minds are identical to bodies, then
whatever is true of minds is true of bodies,
and vice versa.
2. But minds are indivisible and bodies are
divisible.
3. Therefore, minds are not identical to bodies.
The Problem of Interaction
• Descartes believes
that our minds
affect our bodies,
and vice versa.
• But how can a nonphysical object
affect a physical
one?
Parallelism
• One way to deal with the problem of
interaction is to say that the mind and body
only seem to interact with each other.
• According to parallelism, mental processes
and physical processes run parallel to each
other. There is a correlation between mental
and physical events, but no causal
interaction.
Occasionalism and the
Preestablished Harmony
• Occasionalism is the parallelist theory of the
mind that claims the correlation between mental
and physical events is produced on each occasion
by God.
• Preestablished harmony is the parallelist theory
of mind that claims that the correlation between
mental and physical events was established by
God at the beginning of the universe.
The Causal Closure of the Physical
• Descartes’ dualistic interactionism runs afoul
of a basic principle of materialism known as
the “causal closure of the physical.”
• According to this principle, everything can be
explained in purely physical terms.
• Nevertheless, people do have thoughts,
feelings, and desires, and these things seem to
be nonphysical.
• How can we reconcile these facts?
Epiphenomenalism
• Maybe we can reconcile them by admitting the
existence of Cartesian minds and denying them
any causal power.
• According to epiphenomenalism, the mind is an
ineffective by-product of physical processes; the
body affects the mind, but the mind does not
affect the body.
The Problem of Other Minds
• Because Cartesian minds have no physical
properties, they cannot be sensed or detected
by any physical instruments.
• If so, Descartes cannot know that other
people have minds.
Solipsism
• The only mind that we can know for certain
exists is our own.
• Some have made the further claim that the
only mind that exists is their own. This is
known as solipsism.