Tom Nagel, The Mind-Body Problem
1.
Question addressed: What is the relationship between consciousness and
the brain?
2.
Three answers:
a.
Dualism: Two different kinds of things
b.
Physicalism: Identity; they are the same thing
c.
Dual aspect theory: They are two different aspects of the same thing
3.
4.
WHAT WE KNOW/BELIEVE AS A RESULT OF SCIENCE
We know that what happens in consciousness depends on what happens
to the body/brain
a.
That somehow your conscious experience is at least in part tied to
changes in the body.
b.
Examples: Stub your toe, it hurts; Close your eyes, can’t see; Bite into
Hershey bar, taste chocolate; If someone conks you on head, you pass
out
For anything to happen in your mind/consciousness, something has to
happen in your brain
a.
Would not feel pain from toe stub if nerves to brain cut
b.
Although we don’t know exactly what it is that happens in your brain
when you wonder about getting a haircut
i.
We are pretty sure something electrical/chemical changes in the
billions of nerve cells in your brain.
c.
Not sure how science could show this as a general claim
In some cases we do know (roughly) how the brain affects the mind and
how the mind affects the brain
a.
Stimulation of certain brain cells at back of head produces visual
experience
b.
When you decide to have another piece of cake, certain other brain
cells send out impulses to the muscles in your arm
Above is science
5.
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8.
Philosophical question: Is your mind something different from your
brain, though connected to it, or is it your brain
a.
Are your thoughts, feelings, perceptions, sensations, wishes things that
happen in addition to all the physical processes in your brain,
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b.
Or are they themselves some of those physical processes
Taste of chocolate example
a.
All sorts of things happen after one bites piece of chocolate
b.
Taste buds send electronic impulses to brain and further physical
changes take place there
c.
Finally you taste the taste of chocolate
d.
Is that taste just a physical event in some brain cell
e.
Or is it something of a different kind?
Reason to think experience of taste is not something physical: Not
observable by everyone (and all physical things are observable by all)
a.
Scientists who took off top of your skull and looked inside while you
were eating chocolate would only see grey mass of neurons
b.
Could measure electrical/chemical processes
c.
Would not find the taste of chocolate
Scientist would not observe your experience of chocolate even if she
licked your brain
a.
So it is not simply because the experience is a flavor experience that
has to be tasted and not seen visually
b.
Even if your brain tasted like chocolate, he would not have succeeded
in getting into your mind and observing your experience of chocolate
c.
He would have his taste of chocolate and you would have yours
Your experience of the taste of chocolate is locked inside your mind in a
way that makes it unobservable by anyone else
a.
Your experiences are inside your mind with a kind of insideness that is
different from way your brain is inside your head
i.
Someone else can open up your head and see what is inside, but
they can’t cut open your mind and look into it
b.
A person’s conscious experience is observable only from the inside by
a person’s whose consciousness it is and it is not observable from the
outside
14.
If what happens in your experience is inside your mind in a way in which
what happens in your brain is not
Then our experiences and mental states can’t just be physical states of
our brains
a.
Then there is more to a person than her body
15.
Dualism:
a.
b.
16.
17.
There is a soul (or some non-religious mental substance) attached to
your body in some way which allows them to interact
People made up of two very different things:
i.
Physical organism
ii.
Mental stuff (e.g., soul)
Considerations against dualism (existence of soul/mental stuff)
a.
Belief in a soul is old-fashioned and unscientific
b.
Everything else in the world is made of physical matter (different
combination of chemical elements)
c.
Why shouldn’t people also be made of up of this?
d.
Why can’t a complicated physical system like a human body/brain
give rise to mental life?
How could philosophy show that people aren’t merely physical
a.
Philosophy can’t tell us what stars or diamonds are made of so how
can it tell us what people are made of?
18.
Physicalism/Materialism: People consist of nothing but physical matter
a.
People’s mental states are physical states of their brains
b.
Everything that exists is made of physical matter (and only physical
matter), people are no different
c.
???Science eventually will be able to explain everything
19.
Science will discover which states of the brain can be identified with
which mental states (the experience of tasting chocolate, for example)
a.
We will discover that experiences really are brain processes, just as we
have discovered that other familiar things have a real nature we
couldn’t have guessed until revealed by science
i.
E.g., Diamonds are composed of carbon, same material as coal
ii.
Water is composed of hydrogen and oxygen, even though these
two elements are nothing like water when taken by themselves
b.
Might seem surprising that experience of tasting chocolate is nothing
but complicated physical event in your brain
i.
But no stranger than lots of other scientific discoveries
c.
Only a matter of time before science discovers the biological nature of
the mind
20.
Dualist reply
a.
b.
c.
21.
Dual aspect theory (one thing, two properties view)
i.
Dualism: you consist of a body plus soul and your mental life
goes on in your soul
ii.
Physicalism: your mental life consists of physical processes in
your brain
b.
Dual aspect theory: Mental life goes on in the brain (not in your soul)
but those experiences, feelings, thoughts, desires are not physical
processes in your brain
i.
Our brains are not just physicals objects
ii.
They have lots of physical properties/processes, but also have
mental processes as well
c.
Dual aspect theory: Brain is the seat of consciousness but its conscious
states are not just physical states
d.
Bite into chocolate produces a state in your brain with two aspects
i.
Physical aspect involving electrical and chemical change
ii.
Mental aspect–the flavor experience of the chocolate
e.
Scientist looking into your brain will be able to observe the physical
aspect
f.
You will undergo, from the inside, the mental aspect
g.
Our brains have an inside that can’t be reached by outsider observer
even if cut it open
h.
i.
j.
k.
22.
These other discoveries where simply finding out what smaller
physical things made up a physical substance
To analyze mental states in terms of physical states would involve
analyzing an internal (and private) taste sensation by an externally
observable physical substance
Science will never be able to show that a mental phenomenon is a
physical one
You are not a body plus soul (dualism)
You are just a body, but your body (or brain) is not just a physical
system
Object with both physical and mental aspects
There is something it is like from the inside to taste chocolate because
there’s something it’s like from the inside to have your brain in the
condition that is produced when you eat chocolate
Physicalism:
a.
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Believes nothing exists but physical world studied by science, world of
objective reality
b.
They have to find room for feelings, desires, thoughts, and experiences
(for us) in such a world
Functionalist defense of physicalism
a.
Mental nature of mental states consists in their relation to things that
cause them and things they cause
b.
E.g., feeling of pain involves physical characteristic in our brain but
what makes it pain is that it is the kind of state of your brain that is
usually caused by injury and that usually causes you to yell and hop
around and avoid the thing causing the injury
c.
Pain is whatever is caused by injury and causes pain behavior
Nagel’s response
Not enough to make something pain that it causes you to yell and is usually
caused by injury
Pains are pains also because they feel a certain way
a.
And that is different from all their relations to causes and effects as
well as the physical properties they have (if in fact they are events in
your brain)
Nagel does not believe that inner aspect of pain (how it feels) and (of other
conscious experiences) can be analyzed in terms of any system of causal
relations to physical stimuli and behavior
Nagel’s dualism
a.
Two very different kinds of things going on in the world
i.
Things belonging to physical reality which many people can
observe from the outside
ii.
Other things belonging to mental reality which each of us
experiences from the inside in his own case
(1) Probably some other animals have insides like this too
b.
c.
Won’t have an adequate general conception of the world until we can
explain how when lots of physical elements put together in right way
they form not just biological functioning organism but a conscious
being
If consciousness could be identified with some kind of physical state,
we could develop a unified physical theory of mind and body and
perhaps unified physical theory of the universe
d.
e.
29.
Nagel thinks that reasons against purely physical theory of
consciousness so strong that likely a physical theory of the whole of
reality is impossible
Physical science has progressed by leaving mind out of what it tries to
explain, but there is more to the world than can be understood by
physical science
Additional considerations about dualism versus physicalism
a.
Mental states do not have locations (or other physical characteristics)
like physical states to so they must be different
i.
It makes no sense to say of a mental states (that they are at a
certain location (“Where is my belief nature has intrinsic
value?” “How much does it weight and what shape is it and is
it stationary or moving”)
b.
If mental states are not physical it becomes a mystery as to how
mental states can causally affect physical states (the brain) or how a
physical state can causally affect a mental state (the mind)
i.
Assumption: Only something physical can cause something else
physical
ii.
But we know this causal interaction happens
iii. Thus mental states must be physical states