Transcript What is it to Have a Mind?

What is it to Have a Mind?
What is it to Have a Mind?
Two Central Questions:
(1) What are minds?
(2) How do minds relate to/interact with bodies?
What is it to Have a Mind?
Recall our list of mental states:
• Thoughts
• Beliefs
• Desires
• Current experiences and sensations
• Emotions
What is it to Have a Mind?
A mind is something that can be in such states
as these.
But what is a mind and how does it relate to
physical things like our bodies?
Substance Dualism
It is common to think that we are not just
physical things, but that we have a non-physical
nature.
Substance Dualism
Substance Dualism: There are substances of two
fundamentally and irreducibly distinct kinds in
the word: mental stuff, and material stuff.
Substance Dualism
According to substance dualism minds are
immaterial things that are not made up of
physical matter.
This lines up closely with the idea of that we
have a soul or a spirit.
Substance Dualism
It is probably true that the vast majority of
people are substance dualists:
• Most major religions endorse something of
this kind
• Many people believe they can survive the
death of their bodies
• You see this assumed in fiction all the time
(books and movies about ghosts).
Leibniz’s Law
In order to make sense of Descartes’ arguments
it is useful to have the following principle:
Leibniz’s Law: If A and B are numerically
identical then A and B share all of the same
properties.
Kinds of Identity
Qualitative Identity: A and B are qualitatively
identical if and only if A and B have all the same
properties.
Numerical Identity: A and B are numerically
identical if and only if they are one and the
same thing.
Kinds of Identity
So Leibniz’s law says that if A and B are
numerically identical then they must also be
qualitatively identical.
(Not the reverse)
Leibniz’s Law
In other words, if A and B have different
properties then they cannot be the same thing.
Leibniz’s Law
An example of how you might use the principle:
1. Superman is flying across the sky.
2. Jimmy Olsen is not flying across the sky.
3. Therefore, Superman is not Jimmy Olsen.
Argument from Doubt
Argument from Doubt
1. I can doubt the existence of my brain and
body.
2. I cannot doubt the existence of my mind.
3. Therefore, my mind is not the same thing as
my brain or body.
Argument from Doubt
I can doubt the existence of my brain and body.
This premise is supported by thinking about the
evil demon scenario.
In such a case I don’t have a body or brain, so I
can consistently doubt that I have a body or
brain.
Argument from Doubt
I cannot doubt the existence of my mind.
This follows from Descartes’ cogito. I cannot
consistently doubt that I have a mind, because
doubting is a mental state!
Argument from Doubt
Therefore, my mind is not the same thing as my
brain or body.
Follows from the premises by Leibniz’s law.
My body has a property that my mind lacks
(being able to be doubted by me to exist) so
they can’t be the same thing!
Argument from Doubt
If this argument works, then it establishes that
substance dualism is true:
• My mind is not identical to my body
• Therefore they must be two, different things.
A Fallacious Inference
There is problem with how Leibniz’s Law is
applied in the argument from doubt.
A Fallacious Inference
Consider the following argument:
(1) Lois Lane doubts that Clark Kent can fly.
(2) Lois Lane does not doubt that Superman can
fly.
(3) Therefore Superman is not identical to Clark
Kent.
A Fallacious Inference
What if Manti Te’o reasoned as follows:
(1) I believe that Lennay Kekua is dead.
(2) I don’t believe that Ronaiah Tuiasosopo is
dead.
(3) Therefore, Lennay Kekua is not identical to
Ronaiah Tuiasosopo.
A Fallacious Inference
What is going wrong?
You can’t use what we believe, doubt, or can
doubt about things in order to prove that they
are not identical using Leibniz’s Law.
A Fallacious Inference
So we need an argument that does not make
use of Leibniz’s law in this fallacious manner.
Fortunately Descartes gives us one!
The Conceivability Argument
“First, I know that everything which I can clearly and distinctly
understand is capable of being created by God so as to
correspond exactly with my understanding of it. Hence, the
fact that I can clearly and distinctly understand one thing
apart from another is enough to make me certain that the two
things are distinct, since they are capable of being separated,
at least by God……On the one hand I have a clear and distinct
idea of myself, in so far as I am simply a thinking, nonextended thing; and on the other hand I have a distinct idea of
body, in so far as this is simply an extended, non-thinking
thing. And accordingly, it is certain that I am really distinct
from my body, and can exist without it.” (Sixth Meditation)
The Conceivability Argument
The Conceivability Argument
1. If I can conceive of some state of affairs without
contradiction, then that state of affairs is possible.
2. I can conceive of myself as existing without my body.
3. Therefore, it is possible for me to exist without my
body.
4. It is not possible for my body to exist without my
body existing.
5. Therefore, I am distinct from my body. (by LL)
The Conceivability Argument
The entire force of the argument depends on
premise 1: the claim that conceivability entails
possibility.
Conceivability and Possibility
Despite the claim’s intuitive force, most
philosophers think that it is false.
That is, it is possible for someone to conceive of
something, without that thing being possible.
Arnauld’s Triangle
Steve knows about right triangles, but does not
know the Pythagorean theorem (a2+b2=c2)
Suppose we ask him if it is possible to build a
room in the shape of a right triangle with the
following dimensions: 4x7x10.
He may very well say yes!
Arnauld’s Triangle
Furthermore, he may try to imagine the room,
plan where he would put furniture in it, etc.
But such a room is impossible!
Hence, the fact that Steve can conceive of such a
room does not entail that the room is possible.
Amnesia Case
Suppose I have amnesia and don’t remember
my name.
I hear about this terrible instructor: Tim Butzer.
I imagine a world in which Tim Butzer is dead
and I am attending a party to celebrate his
timely demise.
Amnesia Case
But since I am Tim Butzer, it is impossible for
Tim Butzer to be dead, and for me to be
attending a party!
Hence, conceivability does not entail possibility.
Hesperus and Phosphorus
Hesperus is the first visible star in the evening
and Phosphorus is the last visible star in the
morning.
Someone could imagine a case in which
Hesperus is in the sky while Phosphorus is not.
Indeed they may think this happens every
evening!
Hesperus and Phosphorus
But Hesperus and Phosphorous are actually
both Venus!
So every time Hesperus is in the sky
Phosphorous is too (they are the same thing).
Conceivability and Possibility
All three cases share a common feature: the
subject in each is ignorant of some key facts
about the case.
Conceivability and Possibility
But it seems as if Descartes (or we) could be in
precisely the same situation with regards to the
relationship between minds and bodies.
Conceivability and Possibility
Since conceivability does not entail possibility
Descartes’ argument is not sound.
Therefore, we have no good argument for
substance dualism.
Next Time
All we have done is show that some arguments
for dualism are not sound.
Next time we will look at arguments which
attempt to show that dualism is false.
Problems for Dualism
Papers Due on Thursday
Getting Clear on Dualism
According to the dualist:
• Minds and bodies are two fundamentally
different kinds of things.
• Minds are immaterial.
Getting Clear on Dualism
But what does it mean for something to be
immaterial?
Getting Clear on Dualism
Material things have certain kinds of properties:
•
•
•
•
•
Spatial location
Extension
Mass
Motion
Solidity
Getting Clear on Dualism
Immaterial Object: Lacks spatial location,
extension, solidity, motion, mass, or any physical
properties
Dualists claim that minds are things of this kind.
Interactionism
But minds interact with physical things.
• Mental events can cause physical events.
• Physical events cause mental events.
Interactionism
Interactionism: Minds interact causally with
physical things.
Interactionism
Interactionism is an enormously plausible thesis.
It seems to be one of the most basic and
obvious facts about minds that they are able to
interact with bodies.
Interactionism
The main problem for dualism is that it seems to
be inconsistent with interactionism.
First Problem:
Causal Overdetermination
According to every systematic theory of physics
since Newton, every physical event in the
universe has a physical cause.
This is in tension with the dualist’s claims that
some physical events have mental causes.
First Problem:
Causal Overdetermination
Say that I raise my hand.
According to our best physics, there is a physical
cause sufficient to produce this action.
According to the dualist there is also a mental
cause for this action.
First Problem:
Causal Overdetermination
What the dualist has to say to be consistent with
our best science is that my raising of my arm
was causally overdetermined.
First Problem:
Causal Overdetermination
Causal Overdetermination: An event A is
causally overdetermined if it has multiple
causes, each of which would have been
sufficient on its own to cause A.
First Problem:
Causal Overdetermination
There are many events in the clip that would
prevent O.J. from making the arrest:
• Getting his leg caught in the door
• Getting shot 15 times
• Burning his hand
• Getting caught in a bear trap
• Falling off the boat
First Problem:
Causal Overdetermination
So, O.J.’s failing to make the arrest was causally
overdetermined.
Causal overdetermination is clearly possible and
sometimes happens.
First Problem:
Causal Overdetermination
However, as the clip also illustrates, such cases
tend to be a matter of total coincidence.
As a result, though such cases are certainly
possible, it seems that they are coincidental and
rare.
First Problem:
Causal Overdetermination
The dualist must say that every time any person
moves her arm, there is both a physical cause
and a mental cause.
First Problem:
Causal Overdetermination
But this amounts to saying that there are a
stupidly high number of mere coincidences
happening all the time.
First Problem:
Causal Overdetermination
This massive coincidence calls out for some sort
of explanation on the part of the dualist.
If mind’s and bodies interact, what explains the
massive causal overdetermination that results?
Second Problem: Elizabeth’s Puzzle
Princess Elizabeth of Bohemia presents an
argument which seems to show that dualism
simply cannot be consistent with interactionism.
Second Problem: Elizabeth’s Puzzle
Elizabeth’s Puzzle
(1) Physical objects are caused to move by being
bumped into.
(2) The ability to bump into things requires
extension, mass, shape, and motion.
(3) Minds do not have properties like extension,
mass, shape and motion.
(4) Therefore, minds cannot cause any physical
objects to move.
Second Problem: Elizabeth’s Puzzle
Elizabeth argues that if the soul is immaterial, by
definition it does not have the kinds of
properties that would allow it to causally
interact with physical bodies.
Second Problem: Elizabeth’s Puzzle
What this shows is that if dualism is true, minds
cannot cause bodies to move even in principle
because, being immaterial, they lack the right
kinds of properties.
Second Problem: Elizabeth’s Puzzle
“I confess that it would be easier for me to
concede matter and extension to the soul, than
the capacity to move a body and to be moved,
to an immaterial being.” (179)
Second Problem: Elizabeth’s Puzzle
Elizabeth argues in terms of the physics of her
day.
Today physicists recognize lots of other physical
properties that can be causally relevant (charge,
spin, field-strength, etc.)
Second Problem: Elizabeth’s Puzzle
But this doesn’t solve the problem for the
dualist.
If something is immaterial it lacks physical
properties. Whatever properties physicists
uncover, the dualist is committed to saying that
minds lack any of them.
Descartes’ Response
Descartes’ most infamous response located the
soul’s causal powers on the body in the pineal
gland.
Descartes’ Response
“The part of the body in which the soul directly exercises
its functions is not the heart at all, or the whole of the
brain. It is rather the innermost part of the brain, which is
a certain very small gland situated in the middle of the
brain's substance and suspended above the passage
through which the spirits in the brain's anterior cavities
communicate with those in its posterior cavities. The
slightest movements on the part of this gland may alter
very greatly the course of these spirits, and conversely
any change, however slight, taking place in the course of
the spirits may do much to change the movements of the
gland.” (The Passions of the Soul)
Descartes’ Response
Descartes’ Response
The idea seems to be that since the gland is so
small and so central in the brain, that any little
movement could have big results.
Descartes’ Response
But thinking in this way completely misses the
point of Elizabeth’s objection:
• It isn’t that it would be very hard for an
immaterial thing to move a material thing
• Her point is that it is impossible, even in
principle, an immaterial thing to move a
physical thing!
Denying Interactionism
What Elizabeth’s argument shows is that
dualism is incompatible with interactionism.
Therefore, why shouldn’t the dualist simply deny
that minds and bodies causally interact?
Denying Interactionism
The problem for any view like this is to explain
observed facts:
• Every time I decide to raise my arm it goes up.
• Every time someone punches me I feel pain.
• Every time I want to move to the other side of
the room, my body walks over there.
• Etc.
Denying Interactionism
If my mind does not causally interact with my
body, how are we to explain these very common
observations?
Occasionalism
Malebranche suggested that every time you
want to make your body move, God takes it as
an occasion to intervene and cause your body to
move in the way intended.
This doctrine is called occasionalism.
Occasionalism
According to occasionalism the laws of physics
are violated every time I “move” my body.
Every time any person move’s their body is
literally a miraculous event!
Pre-Established Harmony
Leibniz suggested that the apparent interaction was
due to a pre-established harmony:
• God set up the universe with two distinct causal
orders: the mental and the physical.
• He set them up in such a way that though they
never causally interact, they will always be in
sync.
• So when the mental event of my wanting to raise
my arm happens, the pre-established harmony
guarantees that my arm will go up.
Pre-Established Harmony
Think of two clocks set to the same time. They
don’t causally interact, but they can be such that
they always agree on the time.
Leibniz’ idea is that the relationship between
the mental and physical is a lot like that.
Acts of Desperation
Both Malebranche’s view and Leibniz’ seem to
be theoretic acts of desperation.
Acts of Desperation
Since dualism is inconsistent with this kind of
interaction, it must be rejected.
Let’s adopt Elizabeth’s suggestion and consider
the possibility that the mind is a material thing
of some kind.