Philosophy
Philosophy of Mind
Advanced Higher
8462
Spring 2001
HIGHER STILL
Philosophy
Philosophy of Mind
Advanced Higher
Support Materials
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CONTENTS
Page
1.
Teacher’s/Lecturer’s Guide
3
2.
Student Information
4
3.
The Mind/Body Problem
4.
5.
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Introduction
5
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Substance Dualism
7
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The Identity Theory
14
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Functionalism
20
•
Student Activities
25
The Problem of Personal Identity
•
Introduction
26
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The Soul Criterion
28
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The Body/Brain Criterion
31
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The Psychological Continuity Criterion
33
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Student Activities
37
Further Reading
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Philosophy: Philosophy of Mind (AH)
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1.
TEACHER’S/LECTURER’S GUIDE
Although the Mind/Body Problem and the Problem of Personal Identity were not
discussed directly at any stage of the Higher Philosophy course, both are closely
connected to issues familiar to students who have taken the Higher. In particular, this
unit complements and deepens knowledge already acquired concerning the free will
debate (in the Metaphysics section of the unit Problems in Philosophy at Higher), and
the study of Descartes’ Meditations begun in the unit Classic Texts in Philosophy.
Consequently this unit is intended for those students who have already successfully
completed the related sections of the Higher who wish to take their philosophical
studies further.
Descartes’ Substance Dualism is one of the principal themes of the Meditations, and
one of the traditional theories in the philosophy of mind. As we shall see, Descartes’
views on the nature of the mind/body relation stem in large part from his reflections
on the Cogito, this latter issue being familiar to students who have already taken the
unit Classic Texts in Philosophy. This unit goes some way to completing the
student’s understanding of this classic text while introducing him/her to a distinct
philosophical topic.
The Mind/Body Problem is also intimately related to the free will debate. The desire
to preserve human freedom in some meaningful sense has led some philosophers,
including Descartes and Kant, to defend a form of dualism, a materialist philosophy of
mind seeming a threat to human dignity in this regard. And of course what one says
about the relations between mind and body has implications for one’s understanding
of what is essential to each human being. Descartes, for example, identified himself,
his person, with his immaterial mind, his body having no more to do with him than
the clothes he happened to wear during his natural life. The Criterion of Personal
Identity is then closely tied to one’s commitments to positions taken in the
Mind/Body Problem.
Areas of study:
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The nature of the Mind/Body Problem
Substance Dualism, the Identity Theory, and Functionalism
the nature of the Problem of Personal Identity
the Soul Criterion, the Brain/Body Criterion, the Psychological Continuity
Criterion.
By the end of this unit students should be able to:
•
•
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present accurate accounts of the Mind/Body Problem and the Problem of Personal
Identity
present and critically evaluate Descartes’ Substance Dualism, the Identity Theory
and Functionalism
present and critically evaluate the Soul Criterion of Personal Identity, along with
the Brain/Body Criterion and the Psychological Continuity Criterion.
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2.
STUDENT INFORMATION
This unit is a natural progression for those students who have successfully completed
the unit Classic Texts in Philosophy and Problems in Philosophy at Higher. Although
the topics to be studied in this unit have not been discussed directly in either unit at
Higher, they are intimately connected to topics you have already encountered. For
example, one of the classic positions in the Mind/Body Problem is Descartes’
Substance Dualism, a position he defends in the Meditations. Those who have
completed Classic Texts in Philosophy (H) are already familiar with many important
themes to be found in this work. This unit builds upon that foundation and introduces
you to another philosophical topic altogether, namely, the relationship between mind
and body.
Some of you will already be familiar with the free will debate from the Metaphysics
section of Problems in Philosophy. This unit may cause you to revisit the arguments
and positions you studied there armed with the knowledge you will acquire
concerning the Mind/Body Problem. What one says in one area of philosophy more
often than not constrains what you can say in another, and this is true of the free will
debate and the mind/body problem. Many have defended a from of dualism in order
to preserve human freedom. If dualism in the Mind/Body Problem is found wanting,
then this has implications for human freedom. As we shall see, it also has
implications concerning what it is to be a person, the other major topic of discussion
in this unit.
Areas of study:
•
•
•
•
The nature of the Mind/Body Problem
Substance Dualism, the Identity Theory, and Functionalism
the nature of the Problem of Personal Identity
the Soul Criterion, the Brain/Body Criterion, the Psychological Continuity
Criterion.
By the end of this unit you should be able to:
•
•
•
present accurate accounts of the Mind/Body Problem and the Problem of Personal
Identity
present and critically evaluate Descartes’ Substance Dualism, the Identity Theory
and Functionalism
present and critically evaluate the Soul Criterion of Personal Identity, along with
the Brain/Body Criterion and the Psychological Continuity Criterion.
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3.
THE MIND/BODY PROBLEM
Introduction
The Mind/Body Problem is easy enough to state. It concerns the relation between
minds and bodies. What is not so straightforward, at least immediately, is why there
is any problem here at all. It is plain to most people that minds do exist, that bodies
exist, and, at least in the case of human beings and perhaps also in some of the higher
animals, that minds and bodies are often found together in the same entity.
Furthermore, it is obvious that minds and bodies influence each other. The stubbing
of my toe (a physical event) leads to the sensation of pain (a mental event), while my
desire for food (a mental event) leads to my body moving towards the refrigerator (a
physical event). So what is the problem?
The problem is that it is not clear how these commonplaces can be true. A little
reflection on our understanding of minds and bodies is enough to reveal an underlying
tension at the heart of our picture of what it is to be a human being. Consider the fact
that a human being has a mind (if anything does), and so can be attributed mental
properties such as:
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•
•
•
•
•
•
•
consciousness
intentionality (to be explained)
sensations/experiences
desires
beliefs
rationality
life
a first person perspective.
But at the same time human beings have material bodies, and so can be attributed
physical properties such as:
•
•
•
•
•
•
extension in space
location in space
causal relations with other bodies
mass/weight
composed of inanimate ‘building blocks’, molecules, atoms, sub-atomic parts
behaviour governed by laws of Physics.
Now each set of properties pulls in different directions. One set places us in the
physical world, while the other suggests that some aspect of us must be non-physical.
Our physical properties clearly place us in the material world, so it is obvious that we
have material bodies. But our mental properties have tended to make people think
that we must be more than just material bodies. Those taking this view typically ask,
“Can a material thing think?” and “How can an inert, lifeless lump of matter have
beliefs and desires?” Behind such questions lies the assumption that the mental must
be some sort of non-physical property.
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This assumption is not totally unfounded, for indeed it is difficult to see how mental
properties can be a part of the material world. Consider the following: If mental
events like beliefs and desires were wholly physical, would they not have physical
properties? It seems natural to suppose that they would. But this quickly leads to
apparent absurdities. For example, does it make sense to say that a belief weighs so
many ounces (or grams)? And can a belief have a location in space? We do assume
that our minds are roughly where our bodies are; but does it make sense to say that my
belief that tomorrow is Tuesday is quite literally located in some specific part of my
brain, perhaps behind my left ear? Moreover, my beliefs are either true or false. But
can a bit of my brain, or any other physical thing for that matter, be true or false? It is
not clear that this makes any sense at all.
But if we agree that some aspect of us must be non-physical, or immaterial, other
problems emerge. Consider that causal relations require the same type of entity on
both sides of the cause-effect equation. I can hit a cricket ball with my cricket bat, for
example, because both are physical entities. And my body can move the bat, again
because both are physical entities. But if mental properties are non-physical, how can
they causally interact with material bodies? How can my desire to swing the bat
influence my body? Conversely, how can physical damage to my body cause the
sensation of pain? Clearly our minds influence our bodies, and vice versa. But how
can this be so if minds and bodies are not both material?
The challenge, then, is to come up with a theory which explains how human beings
can have both sets of properties at the same time while doing justice to all our
commonplace intuitions about minds and bodies. This is the task facing all the
theories to be examined in this section. The interest of this exercise is that it forces us
to look closely at our picture of what it is to be a human being.
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Substance Dualism
Plato and Descartes are the two great names from the history of philosophy associated
with the position known as Substance Dualism. We will concentrate on Cartesian
dualism here since it is Descartes’ work which has had the biggest influence on
modern thinking. Nonetheless, it is worth pointing out that Substance Dualism has
pre-Christian roots lest anyone be tempted to think that Descartes’ interest in this
theory is to be explained solely by reference to his Christian environment. Our
interest in this theory is purely philosophical in that it is proposed as a solution to the
Mind/Body Problem as outlined in the previous section.
Cartesian Dualism
The essence of Descartes’ position, to be found in the Meditations (particularly
Sections II and VI) is that human beings are composed of two distinct substances, one
mental and one material. Descartes claims that human beings are minds (and so have
all the associated mental properties listed above) but that these minds are embodied,
i.e., that human minds occupy human bodies. But by calling these substances
‘distinct’ Descartes is claiming that minds and bodies can in fact exist apart,
independently of each other, although they are normally found together. This means
that human minds can continue to exist after the death of the person’s body, and that
disembodied existence is a coherent possibility.
Now it is easy to see how Substance Dualism addresses the Mind/Body Problem.
Human beings have two sets of seemingly incompatible properties simultaneously
because they are made up of two radically different substances. But apart from this,
what arguments can Descartes provide in support of his Substance Dualism?
Descartes’ Argument for the Real Distinction
The argument for the real distinction comes in two parts. First there is what might be
called ‘the principal argument’; and second, additional sub-arguments are used to
support one of the premises of the principal argument.
The principal argument can be stated as follows:
1)
Whatever I clearly and distinctly perceive is true.
2)
If I can clearly and distinctly perceive x apart from y, and y apart from x, then x
and y are distinct substances and can exist apart.
Another way of expressing this is to say that if I can understand x without
reference to y, and vice versa, then x and y are distinct entities, and as such they
can exist apart from each other. If I cannot understand x without reference to y
then the two must be intimately related. For example, I cannot understand the
workings of the human body without reference to flesh and bones. Hence
human bodies are not distinct from human flesh and bones and so cannot be
separated from them.
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3)
I have a clear and distinct perception that mind and body are distinct.
4)
Mind and body are distinct.
Preliminary comments
Before presenting the sub-arguments for premise 3, some comment is required
concerning premises 1 and 2. Let us consider the second premise first since it is the
least familiar.
Premise 2 is a statement of the principle of separability which Descartes adopts from
the medieval scholastic tradition of philosophy. At issue for us is why one might be
tempted to accept it. What does our ability to understand x and y have to do with how
x and y might be in the real world? A quick detour through some scholastic doctrine is
required.
Traditionally the Christian God has been conceived to be omnipotent, that is to say,
all powerful. God can do anything, it is held, which does not involve a logical
contradiction. The point of this doctrine for present purposes is as follows: if one can
understand x without reference to another object y, and vice versa, then there is no
contradiction in saying that x can exist apart from y, and vice versa, even if x and y
are in fact always found together. (If there were a contradiction then one could not
really understand x apart from y.) In other words, if one can understand x apart from
y, and vice versa, then it is logically, although not necessarily physically, possible for
x to exist apart from y.
The interest that an omnipotent God brings to this picture is the ability to convert any
logical possibility into an actual physical reality if He/She wishes. Since God can do
anything short of bringing about a logical contradiction, God could see to it that x and
y in fact come to exist apart. But if God can so arrange things that x and y exist apart,
then obviously x and y can exist apart. But this is what is meant when we say that x
and y are distinct.
What we have here is a transition from what a human intellect can understand or
imagine (the realm of logical possibilities) to what is in fact true of objects in the real
world, a transition affected by God’s omnipotence. This is a heady brew, and clearly
the principle of separability requires acceptance of the doctrine of an omnipotent God.
The same can be said of Descartes’ clear and distinct rule as expressed in premise 1.
After reflection upon the Cogito Descartes decided that anything which he can clearly
and distinctly perceive to be true must be true. But such was his scepticism of
Meditation. I that Descartes needs grounds for accepting the clear and distinct rule.
Descartes famously employs God as epistemological guarantor: I can rely on my clear
and distinct perceptions, says Descartes, because God is no deceiver. It is clear then
that the success of the argument for the real distinction relies heavily upon the
assumption that God exists and that He/She has the features Descartes attributes to
Him/Her.
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The Sub-Arguments
Leibniz’ Law
In each of the sub-arguments Descartes employs what has come to be known as
Leibniz’ Law. Simply stated, Leibniz’ Law insists that if an object A is identical to
object B, i.e., if A is the same entity as B, then everything that is true of A must be
true of B. This is not particularly profound, since all it says is that when A and B are
in fact the same object, A and B have the same properties.
But Descartes can use this Law in the following way: if he can find something that is
true of his mind which is not true of his body, or vice versa, then he will have shown
that his mind and his body cannot be the same thing (if they were the same thing,
everything that is true of the one would be true of the other). And if they are not the
same thing, then they are different, which is to say that they are distinct.
This is the strategy used to support premise 3 of the principal argument. If he can find
something that is true of his mind but not true of his body, or vice versa, then he will
clearly and distinctly perceive that mind and body are distinct. If he can show this,
Descartes believes that he will have established his Substance Dualism. Again
reflection on the Cogito produces two properties that Descartes thinks serve his
purpose.
The ‘Knowability’ Argument
Recall that Descartes accepts the Cogito, i.e., that “I am, I exist” is necessarily true
whenever it is uttered or conceived. But once he recognises that he knows that he
exists, he confesses that he does not know what he is. All he knows is that he is a
thinking thing. For Descartes this means that, whatever else he might be, he is at the
very least a mind.
So Descartes knows that he has a mind. The next crucial point is Descartes’
recognition that he does not know that he has a body. Knowability, then, is a property
or feature in respect of which Descartes’ mind and body differ. Descartes knows he
has a mind; but he does not know he has a body.
Employing Leibniz’ Law, Descartes then asserts that his mind and body cannot be
identical. If they were identical, everything that is true of the one would be true of the
other.
The ‘Dubitability’ Argument
Descartes then turns the former argument around to produce a second. While
Descartes can doubt that he has a body, he cannot doubt that he has a mind (for
reasons already familiar from above). Employing Leibniz’ Law once more, Descartes
then asserts that his mind and body cannot be identical. If they were identical,
everything that is true of the one would be true of the other.
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With these two arguments in place Descartes believes that he clearly and distinctly
perceives that mind and body are distinct, which appears as premise 3 of the principal
argument.
Problems with the Argument for the Real Distinction
This argument suffers from a number of difficulties which are normally thought to be
fatal.
1)
The viability of this argument clearly relies on the assumption that God exists
and has the features attributed by Descartes. The reliance upon God is quite
complex. First, Descartes needs God as a guarantor of the reliability of his clear
and distinct perceptions. Until an argument for God’s existence has gained
widespread consent, Descartes’ reliance upon his clear and distinct perceptions
remains to be justified. Perhaps some argument can be produced (what better
reason is there for believing a proposition could one have?), but it is certainly
not here in Descartes’ own work. (His own work suffers from the problem of
circularity, familiar to everyone from Classic Texts in Philosophy.)
Perhaps more importantly, Descartes needs God in order to make the principle
of separability acceptable. The transition from what human beings can
understand, clearly and distinctly perceive, or conceive (the realm of ideas) to
the way things actually are out there in the real world (the realm of being)
requires an omnipotent God who can actualise any logical possibility. Without
this power there is no reason to suppose that logical possibilities, simply in
virtue of being logical possibilities, can be actualised in this world.
Consider the following: The proposition “The cow jumps over the moon”
contains no logical contradictions. Does this mean that the cow might actually
be able to jump to the moon? It’s a logical possibility, true; but it is not
physically possible given the laws of nature. This is to say that “the cow jumps
over the moon” will never be true in this world despite the fact that it is
logically possible (unless we have a very radical change in the physical structure
of the universe).
(But what would you say if you could be persuaded that there was an
omnipotent God? If there were such an entity the gulf between the logical and
the physical could be breached.)
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2)
Putting problems of God aside, there is a serious flaw with the two subarguments. This flaw can be summarised by the claim that Leibniz’ Law does
not apply in intentional contexts. This is to say that what one can know or
believe or hope or desire about an object cannot be counted among the ‘real’, or
identifying properties of that object. A property is ‘real’ if the object has that
property regardless of what anyone happens to think about it.
Consider the following illustration of the failure of Leibniz’ Law in an
intentional context. In comic book fiction Clark Kent is Superman. Superman
and Clark Kent are one and the same person (are identical). But Lois Lane is
not aware of this fact. In fact she thinks that Superman and Clark Kent are two
distinct persons. Her reasoning on this score could be presented as follows:
•
•
I, Lois Lane, believe Superman can fly and
I do not believe that Clark Kent can fly.
Applying Leibniz’ Law I can assert that Superman and Clark Kent are distinct
persons because there is something which is true of the one which is not true of
the other, namely my belief that one can fly and that the other cannot.
The point of this illustration is that what Lois Lane believes about Superman and what
she believes about Clark Kent tells us more about Lois Lane than it does about
Superman and Clark Kent. And this is because what someone believes about x is not
an identifying property of x at all. The corollary to this is that Leibniz’ Law only
applies to the real or identifying properties of A and B.
Now both of Descartes’ sub-arguments make the same mistake as Lois Lane’s.
Descartes takes what he can know and doubt of mind and body as identifying
properties of mind and body. But on the basis of these arguments Descartes could be
just as mistaken as Lois Lane.
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Further Problems with Substance Dualism
Even if we assume that Descartes’ arguments have failed to establish the truth of
Substance Dualism should we give up on Substance Dualism? Is it not still possible
that other more successful arguments might be found in its favour? Although this is
theoretically possible there are substantial objections to the coherence of Substance
Dualism itself, regardless of what arguments are brought forward in its favour.
1)
Problem of Causal Interaction
We noted above that there is a two way causal interaction between the mental
and the physical. To repeat the mundane example from above, the stubbing of
my toe (a physical event) leads to the sensation of pain (a mental event), while
my desire for food (a mental event) leads to my body moving towards the
refrigerator (a physical event). More interesting cases of interaction include the
ability of physical substances (drugs, alcohol) to alter mental states. But
however interesting or mundane the example the problem remains the same. If
the mental is non-physical, how can there be causal interaction between minds
and bodies? If minds are non-physical then they are not located in space. How
are physical objects, which are in space, to ‘get at’ minds to influence their
behaviour? There is no point of contact at which a causal interaction can be
effected.
Moreover, Substance Dualism runs foul of the principle of ‘causal closure’, an
assumption deeply imbedded in the physical sciences. The assumption is that
only physical objects, events and processes can causally interact with other
physical objects, events and processes. This assumption captures the essence of
the view that there can be no non-natural or super-natural forces at work in
nature. The success of the sciences combined with our inability to conceive
how minds and bodies could interact pose a serious challenge to the coherence
of Substance Dualism.
Descartes’ response to this challenge was to claim that causal interaction took
place in the penial gland. But this view is radically unsatisfactory since it does
not deal with the problem at all. He later admitted that causal interaction could
not be explained, that it was in fact a mystery. But if a theory makes a mystery
out of a commonplace event, we are entitled to ask if any other theory might not
do a better job.
There have been various reactions to this challenge. Two of the historically
most famous reactions, the occasionalism of Malbranche and the Pre-established
Harmony of Leibniz, preserved Substance Dualism at the cost of dropping
causal interaction. In effect, these philosophers maintained that minds and
bodies were distinct substances, as Descartes had said, but that any causal
interaction between them was merely an illusion preserved by the workings of
God. As neither of these views is given much credence today they are
mentioned only as a matter of historical interest.
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2)
Violation of Biology
Substance Dualism also runs foul of much widely accepted biological theory. It
is now widely accepted, for example, that life, including its attendant mental
properties, evolved out of inert, non-mental matter. Indeed the mind is a
relative late comer to this universe, arriving only after aeons of lifeless
inorganic physical and chemical processes. This same order of things, the
mental evolving out of the purely physical, is repeated at the level of each
individual as well. We all begin life with the union of sperm and egg cells,
neither of which shows any signs of mental activity. And yet at the end of a
long process of development the mental emerges out of what was a wholly
physical beginning.
Now if Substance Dualism is correct we need to know at precisely what
moment a soul or mind is infused into this otherwise purely physical process,
and how this infusion takes place.
3)
It is uninformative about the nature of the mind.
One of the other common objections to Substance Dualism is that it has very
little to say about the mind at all. The mind is always characterised negatively
as immaterial, or non-physical. When compared to what we are now learning
from the neuro and cognitive sciences, Substance Dualism pales into
insignificance as a source of information about the entity at the heart of the very
theory.
4)
It begs the question.
As we noted at the outset, our mental properties have tended to make people
think that we must be more than just material bodies because it seemed
inconceivable that a wholly material thing could think, or that a mindless lump
of matter could develop beliefs and desires. Behind this view is the assumption
that the mental must be something non-physical. But this is to beg the question
right from the start. Perhaps it was difficult to avoid this attitude before the
frailties of Substance Dualism were exposed. But now we must be willing to
countenance the thought that wholly material things can think, believe and
desire. It is this suggestion which materialists (or physicalists) take seriously.
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The Identity Theory
Descartes’ approach to the Mind/Body Problem was to posit two distinct substances
(hence the term ‘dualism’). Materialists, by contrast, are monists, which is to say that
they believe that there is only one type of substance. Materialists, as the name
suggests, maintain that all that exists is material or physical in nature, and that in one
way or another all mental phenomena are to be explained in terms of the physical.
(Some monists have held that all that exists is mental, but this option will not be
pursued here as it has few defenders today.)
There are various materialist theories of mind, one of the most popular being the
Identity Theory. The core idea of this approach to the Mind/Body Problem is the
claim that the mind is just the brain. Identity theorists maintain that mental events are
a special kind of physical event, specifically states or processes of brains. The
technical term ‘reduction’ is often used to state the theory more precisely (indeed the
Identity Theory is properly described as a form of ‘reductive materialism’). It is
worth while spending some time getting clear about what is meant by ‘reduction’.
Reduction
In general reduction occurs when one theory, conceptual scheme, or area of discourse
is absorbed into another. Historically this tends to occur when it is discovered that
what was ostensibly two or more distinct entities are in fact one and the same thing.
When such a discovery is made it is usually counted as a great success. Indeed, this is
the stuff of great science, since what we end up with is a simpler overall theory with
greater explanatory power than was originally appreciated. An example from the
history of science will help, for it is in the sciences that the notion of reduction was
first employed.
The leading idea in the natural sciences of Physics and Chemistry for the last 200 odd
years has been that the behaviour of ordinary-sized objects encountered in daily
experience (trees, cows, the various inorganic substances like iron, sulphur, etc.) can
be explained by reference to molecules, atoms, their sub-atomic parts, and the forces
governing their inter-relations. The rationale behind this idea is the belief that all that
really exists is matter in motion, matter being made up of molecules, atoms, their subatomic part, etc. If this is true, then everything we encounter in daily life must simply
be complex parcels of molecules, atoms, etc. If so, then the behaviour of complex
entities or collection of entities (ordinary-size objects) is to be explained by reference
to the properties of their component parts. If the behaviour of ordinary-sized objects
at the macro-level can be explained in terms of molecules and atoms at the microlevel, then ordinary-sized objects will have been ‘reduced’ to molecules and atoms.
The following famous example from the history of science will illustrate reduction at
work. It is now said that thermodynamics (the study of what used to be thought of as
a substance, namely heat), has been reduced to mechanics (the study of how material
bodies affect one another). At one stage in the history of science the phenomena
associated with heat were explained by reference to a substance called ‘caloric’.
Philosophy: Philosophy of Mind (AH)
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An increase of this substance in a body was thought to warm that body; and when
bodies lost this substance they cooled down. But it came to pass that the phenomena
associated with heat came to be explained by reference to the state of the molecules in
the body under study. Rather than saying that bodies heat up because of an infusion
of caloric, scientists realised that bodies heat up when the activity of their own
constituent parts increases. Heat is now defined, not as caloric, but as the mean
kinetic energy of molecules. Heat phenomena are now explained by reference to how
the speed at which the molecules of one body are moving can affect the motion of
molecules in another body.
The result of this is that ‘caloric’ has now been eliminated from scientific theory, and
instead of two distinct sciences, thermodynamics and mechanics, the two are now
seen to be very intimately related, thermodynamics being a branch of mechanics.
This famous incident from the history of science illustrates what the identity theorists
hope to accomplish with mental phenomena. Rather than explaining them by
reference to a distinct substance, a non-physical mind, identity theorists hope to show
that the mind reduces to states of brains in the same way that heat reduces to the mean
kinetic energy of molecules.
Some points of clarification are in order. First, it is important to recognise that while
Identity Theorists are happy to say that there is no immaterial mind (in the same way
that there is no caloric) they are not claiming that there are no mental phenomena (in
the same way that no one denies the existence of heat). What has changed is the way
in which mental phenomena are understood. Mental phenomena are thought of as
special kinds of physical states. This is important because there are philosophers
(Paul and Mary Churchland, and possibly Quine) who go farther than the Identity
Theorists by claiming that, strictly speaking, there are no mental phenomena either.
This view, known as eliminativism, is not to be confused with the Identity Theory.
Secondly, Identity Theorists are first and foremost materialists. As such they believe
that all that really exists is physical, and that everything can be explained in terms of
physical events and processes. However, materialists need not claim that everything
can be reduced to Physics per se. All that is claimed is that everything can be
explained by some branch of the sciences, whether that science is reducible to Physics
or not. In this case, if the mind can be reduced to a branch of Biology, the neurosciences say, the Identity Theorist will be more than satisfied.
Finally, materialists are not claiming that everything can be explained by current
sciences, only that the methods of the sciences in principle can explain everything.
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Type vs. Token Identity
In the early days of the Identity Theory it was thought that types of mental phenomena
would be found to be identical to types of brain states. For example, it was thought
that all kinds of pain would be found to be identical to a certain type of brain activity,
namely c-fibres firing. This was called type-type identity, since types of mental state
were matched to types of brain state. But this version of the Identity Theory has
fallen into disfavour on the grounds of ‘chauvinism’. Is it not credible, it was thought,
to believe that other animals feel pain? If animals do feel pain that is (functionally?
qualitatively?) similar to our own, then we must admit that pain need not be identical
to c-fibres firing because animal brains are not human brains. The reaction, naturally
enough, was to say that all mental phenomena are identical to some material states but
that these states vary from instance to instance. This is known as token-token
identity, because an instance or token of pain, for example, is matched with an
instance or token of some physical state (c-fibres firing in humans but something else
in other cases of pain). This is now the most popular form of the Identity Theory,
and, as we shall see, it is accepted, at least tacitly, by most Functionalists as well.
Arguments in favour of the Identity Theory
1)
Any theory that attempts to address the Mind/Body Problem has both positive
and negative arguments in its favour. The negative arguments are those
problems the alternative theories face which the one in question manages to
avoid. In the end we may have to opt for the least objectionable of the available
theories, no single theory being completely without difficulties. That said, the
Identity Theory benefits from not having the difficulties facing Substance
Dualism. For example, there is no causal interaction problem it must resolve,
nor is it forced always to characterise the mind in negative terms, and it sits well
with all of the natural sciences, in particular evolutionary biology and the brain
sciences.
2)
On the positive side, the Identity Theory does justice to the physical aspects of
human beings. Moreover, if the mental can be reduced to the physical, it will
account for our mental properties as well. And since the sciences have managed
to reduce various ‘higher-level’ entities and phenomena to the micro-level, there
is every reason to be hopeful that the same will happen in this case as well.
Indeed, current neurobiology is making great improvements in our knowledge
of the brain, and it is only a matter of time before the various identity relations
are found.
3)
It is a simpler theory than dualism since it posits only one fundamental
substance as opposed to two with no loss of explanatory power.
Philosophy: Philosophy of Mind (AH)
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Problems with the Identity Theory
1)
The problem of Intentionality
Intentionality is often taken by philosophers to be the essential feature of the
mental – consciousness being the other main contender. Beliefs, desires, hopes,
wishes and other propositional attitudes all display ‘intentionality’, which is
usually characterised as ‘aboutness’ or ‘directedness’. For example, the belief
that Bill Clinton is the President of the United States is a mental state, but it is
about a certain object, namely Clinton. My desires are all mental states, but
they are all about or for something else distinct from my mind, e.g., a cup of
coffee. Purely physical states do not have this directedness or aboutness; they
are purely self-contained.
Now some mental events do not display intentionality. Pains are a good
example. If my big toe hurts, this hurt is not in any sense about something else.
It just is. But if something does display intentionality it is definitely mental.
But for our present purposes all we need to recognise is that intentionality has
yet to be reduced to brain states, and it looks as though it never can be. If this is
so, then the Identity Theory cannot be correct.
The reason for thinking that intentionality is a genuine problem is that it is not
clear how a brain state can be about anything. My belief that Clinton is the
president of the US is mental and is about something. But could my
corresponding brain state be about Clinton? Physical events just are, and no
physical or chemical examination of my corresponding brain state could reveal
that it was a belief about Clinton. And other properties follow on from the
intentionality of my beliefs that pose further problems for the identity thesis. As
noted at the opening stages of this discussion, my beliefs can be true or false,
and this is so because they can correspond or fail to correspond to the facts (i.e.,
because they are about the facts). But my brain states cannot be true or false,
they just are. And so we can use Descartes’ strategy and employ Leibniz’ Law
in a new context. Mental states have intentionality, brain states do not; ergo
they cannot be identical.
2)
The problem of Qualia
Materialism is the view that reality is entirely physical, that all that exists is
matter in motion. If this is so, then if we were somehow able to know all of the
physical facts, then there would be nothing left for us to know, reality having
been exhausted. But many philosophers have argued that there are some
knowable facts which are not physical. If this is the case, then materialism and
the Identity Theory cannot be correct. A famous thought experiment, called
“What Mary doesn’t know” tries to make this point.
Philosophy: Philosophy of Mind (AH)
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Imagine a girl, Mary, who has never experienced colour. She has been kept in a
black and white room all her life. She has a black and white TV, and access to
all manner of books and learning materials. She is able to watch lectures on TV
on Physics, Chemistry, Biology, Optics, and any other discipline you could care
to imagine. The point of the thought experiment is to allow Mary to know all
the physical, chemical, and physiological facts one needs to know in order to
appreciate the world of colours. But she has never experienced any colours
herself.
Imagine now that Mary is let out of the black and white room (and try to ignore
the fact that of course she will be terribly maladjusted, and have an enormous
chip on her shoulder etc.). Now for the first time she experiences colours with
her own perceptual apparatus. The question is: Is there now something that
Mary knows that she did not know before? Many have thought the answer is
yes. She now knows what it is like to experience red, for example. This is not
something she knew before, even though she did know all the physical facts
associated with colour experience.
If you think there is something Mary didn’t know, then physicalism and the
Identity Theory cannot be correct, for there is now a real feature of Mary, her
knowing what it is like to see red, which is not capturable in purely physical
terms. This feature, and others like it are called qualia. Qualia have been
described as the ‘what it’s like’ character of mental states. The way it feels to
have mental states such as pain, seeing red, smelling a rose, etc
3)
Consciousness and the First Person Perspective
The problem of qualia is closely connected to the problem of consciousness and
the first person perspective. But to see the problem posed by consciousness we
must first notice a feature of the material world. The material or physical world
is a public world, a world to which we all have access. And because we all have
access to it, it is objectively describable, which means we can get it right and we
can get it wrong – our errors being open to correction by comparison with the
world itself. It is this public, accessible nature of the physical world which
allows for the growth of an objective science.
By contrast, for each and every mental entity there is a set of private, subjective
experiences which go to make up what it is like to be that particular mental
entity. They are private because no one else can have them. While we might
both see the same thing, you cannot have my seeing of the thing, nor I yours.
They are subjective because there is no right or wrong about experiences, they
simply are what they are. No one can correct my experiences (although I might
not always report them accurately, or interpret them correctly).
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What has this to do with the Identity Theory? If private, subjective first person
perspectives are a real feature of the world, and materialism is true, then
materialism must be able to provide a complete account of the nature of
consciousness and first person perspectives. But many philosophers, like
Thomas Nagel, say this is impossible. They argue that materialism only allows
for an objective, third person, or outsider’s perspective of things. But
consciousness is irreducibly in the first person, experienced from the inside, as it
were, and so materialism can never give a complete account of consciousness.
To bring this point home Thomas Nagel has asked that we consider what it is
like to be a bat. Although it is difficult if not impossible to put yourself into the
shoes of a bat, there is little doubt that bats have bat-experiences, even if we
cannot have them ourselves. The reason for this is that bats, like all mental
entities, are conscious, and that they are conscious of their world from a
particular point of view, their own private, ‘first person’ perspective. But no
amount of bat-neuroscience is ever going to allow us to know what it is like to
be a bat, to have a bat’s experiences, and for precisely the same reason that no
amount of neuroscience will let me have your experiences. Science and
materialism can only provide a third person, objective, outsider’s perspective of
a bat’s experiences by recounting the physical processes at work in the bat’s
neuro-system. But this perspective is blind to first person experiences and
perspectives because no amount of science is going to let us experience these
neural processes from the inside. But since they exist, and materialism cannot
accommodate them, indeed must deny their existence, materialism and the
Identity Theory must be false.
Identity Theorists counter this argument by stating that any creature’s conscious
states depends or supervenes in an objective way upon its perceptual apparatus.
One can only have the experiences your physical organism and systems permit
(bats will have bat-like experiences because they have bat perceptual systems).
So in one sense you can say in an objective manner what those conscious states
are like. Although this is undoubtedly true, these accounts still do not capture
what it is like to have these experiences, what it is like to undergo life as a bat.
And so the point of Nagel’s challenge has not been met.
Philosophy: Philosophy of Mind (AH)
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Functionalism
In the mid-70’s the Token Identity Theory was the most popular of the available
theories concerning the Mind/Body Problem in large part because it was thought to be
the least objectionable. But Hilary Putnam, the inventor of Functionalism, asked a
very important question, a question which was to open new avenues of research
concerning the Mind/Body Problem. Accepting the token identity of mental states
and physical states, he asked what two distinct neurological states must have in
common if they are to be identical to the same mental state. For example, if pain in
humans is c-fibres firing, but pain in Gorillas is, say, a-fibres firing, what is it about
these two neurological states that makes both of them an experience of pain? Do they
feel qualitatively similar? Well, for reasons already examined above, we could never
know if they are qualitatively similar because we can never feel anyone else’s
experiences.
Putnam’s leading idea was that what made both neurological states experiences of
pain is the similar causal role or function played by that state in the life of the
organism. The essence of pain, and for that matter any mental state, is how it
mediates between the sensory inputs the organism receives from the outside world
and its resulting behaviour. The mental life of an organism is a matter of receiving
information from the outside world (the passive stage), processing that information
(the reactive stage of interpreting the information, formulating responses) and then
producing the required behaviour (the active stage). So any state is a pain state which
plays the role of pain, that is to say, reacting to physical damage to the body and
producing retreating behaviour, appeals-for-help behaviour, etc.
One of the consequences of Functionalism is that it opens up the theoretical
possibility of artificial intelligence. While most functionalists accept a version of the
Token Identity Theory in the sense that all mental states at the very least supervene
upon some physical state, that physical state need not be an organic one. In the same
sense that the type Identity Theory was deemed chauvinistic, so too is the assumption
of organic token identity. If a computer, for example, has internal states which are
functionally equivalent to some of our organic states (it is an information processor
after all), and if the essence of any mental state is its functional role, then why deny
mental states to computers?
This prospect has launched the now booming industry of Artificial Intelligence. It has
also produced one of the leading metaphors concerning the relation of the mental to
the physical. Putnam suggested that the human mind could be seen as a type of
computer. Those taking this view liken the brain to the computer’s hardware, and the
mind to the software program it runs.
But there is also a further consequence, one not always taken seriously by
Functionalists themselves but no less real for that. The key idea of Functionalism is
the new way of determining what the essential features of a mental state are.
Substance Dualists claim that they are states of some mental substance, identity
theorists of both varieties that they are identical to some neurological state.
Philosophy: Philosophy of Mind (AH)
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Functionalists abstract from the ‘substance’ issue altogether. What is essential to a
mental state is not what substance it is made of, but its functional role in the career of
the organism or computer, or whatever. This in effect re-opens the door to an
immaterial mind. If a non-material entity, if such things exist, were able to manifest
the appropriate causal roles, then this too would be mental. So Functionalism is
compatible with a non-physical mind.
Supervenience vs. Reduction
The fact that the Functionalist abstracts from the ‘substance’ issue opens up the
question of the relationship between Functionalism and Materialism and
Functionalism and a non-physical mind (whatever that might be). But as a matter of
historical fact most Functionalists have been Materialists in the sense that they
maintain that mental states are intimately related, indeed inseparable from some
physical state. But they do not hold that the mental can be reduced to the physical
because the essential characteristics of the mental, its causal role, cannot be described
in terms of Chemistry and Physics, and because the same causal role can be played by
different physical systems. So strictly speaking, although most Functionalists are
Materialists, they do not claim that mental states are identical to physical states. Most
Functionalists maintain that while mental states are purely physical they are not
wholly describable in purely physical terms. So what then is the relation between the
mental and the physical as far as these Functionalists are concerned?
Supervenience
Functionalists have had recourse to the notion of supervenience in order to deny
Substance Dualism without claiming that everything can be reduced to the physical.
The supervenience relation is supposed to serve precisely this function, and is
typically characterised as follows:
A is said to supervene on B if:
i)
It is impossible for A to exist without B. (This is ontological dependence. So,
if there is no physical basis, there can be no mental phenomena.)
ii)
It is impossible for B to change without A changing. (This is known as property
co-variation. So, if my brain chemistry or physiology changes, then my mental
properties must also change if the mental supervenes on the physical, and
similarly for any other material entity which displays mental properties.)
iii)
But despite (i) and (ii), A is not reducible to B. (Non-reducibility. It is this
feature which is supposed to distinguish the supervenience relation from that of
reduction.)
The notion of supervenience is now very popular among Materialists because it
clearly eschews dualism without explicitly stating that the mind is identical to the
brain.
Philosophy: Philosophy of Mind (AH)
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Supervenience is indeed tailor-made for non-reductive Materialists. It saves the
primacy of the physical, the dependence of the mental upon the physical, all without
reductive implications. But questions need to be asked about this relationship. There
is some dispute as to whether supervenience does not in fact amount to reduction. For
purposes of simplicity I have ignored the distinctions between definitional,
nomological and mereological reduction, and the various types of supervenience.
And it may well be that supervenience (in some guise) of the mental upon the physical
is indistinguishable from at least one type of reduction. But until these debates have
run their course, relying on supervenience buys time for the Functionalist by delaying
the moment of truth when the nature of the relationship is really spelled out.
Arguments in favour of Functionalism
1)
First the negative arguments. To many it seems the least objectionable of the
theories so far discussed, for it avoids the problems of Substance Dualism, and
(perhaps) some of the problems of the Identity Theory. Since functionalists rely
on the notion of supervenience, and hence deny that the mental is fully reducible
to the physical, they may be able to avoid some of the problems posed by the
reductionist strategy of the Identity Theorist.
2)
On the positive side: the Functionalist gives an accurate account of mental
activity within an organism (or computer, or non-physical mind) insofar as
minds and mental activity do mediate between sensory input and behavioural
output.
Problems with Functionalism
1)
The Problem of Qualia
We have already met this problem before in the case of the Identity Theory, and
the problem is essentially the same here: Functionalism cannot do justice to the
‘raw feels’ of experience. Since these ‘raw feels’ are an essential feature of
experiences, any theory of the mental which leaves them out of the account is
radically incomplete.
Take the example of pain. According to the functionalist, the essence of pain is
the causal role it plays in the input-output relations of the organism. There is no
mention of the feeling of pain in this definition, no mention of the what-it-islike-to-be in pain. But surely the essence of pain is that it hurts. Pain does arise
as a result of bodily damage, and it does lead on most occasions to certain types
of behaviour; but any theory of pain which does not mention the experiential
quality of pain is radically incomplete.
Philosophy: Philosophy of Mind (AH)
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2)
The Inverted Spectrum
This argument is akin to the former in that it relies on the nature of a mental
experience. It is possible for two physical states to display exactly the same
causal role in their respective organisms while the experiential quality of the
two physical states are radically dissimilar. For example, someone with
abnormal colour vision will learn his colour terminology in the same way that
those with normal vision would, by being exposed to certain colours while
names like ‘red’, ‘blue’ etc. are uttered, then go on to use these terms in a
similar fashion to those with normal vision. But in this case the normal
perceptual systems will produce one qualitative experience (an experience of
red, say) while those with the abnormal system will experience something quite
different (perhaps an experience of grey). These experiences differ in their
qualitative features; but their role in the mental life of the organism is identical.
Since the Functionalist cannot account for these differences Functionalism
cannot give a complete account of the mental.
3)
Problem of Intentionality
Again we have already met this problem in the case of the Identity Theory. The
task for Functionalists is to see if they can do any better than Identity Theorists
in accounting for intentionality. Fodor and others have tried to claim that causal
states can represent things in the outside world in much the same way that
symbols represent things. However Putnam has shown that representations do
not supervene upon the physical as the Functionalist must maintain. That is,
two physically identical brain states in identical causal roles can ‘represent’ or
be about two completely different objects. Putnam showed this in his now
famous ‘Twin Earth’ thought experiment.
Imagine a world which is atom for atom identical to Earth except for one
particular feature. Water on ‘Twin Earth’ looks like, smells like, tastes like, in
fact behaves in all respects like earth water except that instead of being H2O it is
composed of XYZ. Now imagine Oscar and Twin Oscar thinking about water
in their respective worlds. The thoughts of both Oscars are physically and
functionally identical, but one is about H2O and the other is about XYZ. They
do not represent the same thing. But since the mental representation is different
while the physical bases are identical, the mental does not supervene upon the
physical.
4)
Searle’s Chinese Room
Functionalism, as we have seen, is committed to the possibility of artificial
intelligence at least in principle. For if a computer can be shown to have
internal states that play a similar causal role to our own mental states, then there
is no reason why we should not speak of these computers as having minds or
mental states. Many have sought to prove that computers can think by
producing computers that react and behave in ways that are indistinguishable
from the behaviour patterns of indisputably mental entities. This was the point
of the so-called Turing Tests.
Philosophy: Philosophy of Mind (AH)
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But John Searle produced an argument, now known as the Chinese Room,
which shows that even if a computer could pass the Turing Test we would have
no reason to think that the computer had a mind, or was conscious, or properly
mental in any meaningful sense. His argument was first put forward to show
that computers are not mental entities; but since by Functionalism’s lights the
computer that passes the Turing Test would count as a mental entity, the
argument can be used against Functionalism as well. In effect, Searle’s
argument shows that the essence of the mental cannot be captured by the inputprocessing-output relation, that something important is left out of the account,
and so that at best Functionalism is an incomplete theory of mind.
Searle’s thought experiment involving the Chinese Room scenario goes
something like this. Imagine you are placed in a room with two openings, one
through which you receive signs bearing Chinese characters, the other through
which you pass other signs bearing distinct Chinese characters. Imagine further
that you do not understand Chinese. Inside the room, however, is a book
containing instructions. The book tells you what signs to pass through the ‘out’
opening depending on what signs you receive from the outside. Unbeknown to
you, Chinese speakers understand the signs you receive from outside, and that
they pose intelligible questions, and that the signs you pass out contain
intelligible answers to those questions. The illusion is then created among
Chinese speakers that something in the ‘Chinese Room’ understands Chinese.
Now the point of the story is that in fact nothing in the room understands
Chinese, and that computers are analogous to the Chinese Room. The story also
relies on a standard distinction in linguistics between syntax and semantics. The
rules of syntax cover the relations between signs. These rules stipulate how
signs can be combined into grammatically acceptable expressions. Semantics
on the other hand is about the relation between signs and the things they
represent, or what they mean. Searle’s point is that computers can handle
syntax, but not semantics. But it is in the realm of semantic relations that the
mental properly resides.
A note of warning by way of conclusion
Virtually all of the arguments brought against Functionalism and the Token Identity
Theory are contested by defenders of these two theories. This is to say that there
haven’t been any conclusive arguments produced by either side, and both are still very
much explanations which have active support. There have even been attempts to
resurrect Dualism in some quarters since the materialist theories have got such serious
problems of their own. These support materials have therefore been limited to a
presentation of the main claims of the theories themselves, and an account of the main
arguments used both for and against them.
Philosophy: Philosophy of Mind (AH)
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Student Activities
1.
Explain in 400 words or less just what the Mind/Body Problem is.
To prepare, try explaining the problem to a friend or family member who has no
background in philosophy.
2.
What are the essential claims of Descartes’ Substance Dualism?
3.
Give an account of Descartes’ principle argument for the Real Distinction.
Take care to explain the principle of separability.
Can you make sense of this principle?
4.
What is wrong with Descartes’ sub-arguments for the Real Distinction?
Take care to explain why Leibniz’ Law does not apply in intentional contexts.
5.
What is the causal interaction problem?
Why is this such a problem for Substance Dualists?
6.
What is the essential claim of the Identity theorists?
7.
What is the difference between Type and Token Identity Theories?
8.
Explain the notion of reduction in 200 words or less.
How does the Identity Theorist hope to employ this notion?
9.
Explain the difference between first and third person perspectives.
Why does this distinction cause problems for Identity Theorists and
Functionalists?
10.
What is the essential claim of Functionalism?
11.
What is the difference between supervenience and reduction?
12.
What are the standard objections to Functionalism.
Do you think these are fatal?
13.
Do you think computers can think?
Give an account of Searle’s Chinese Room Scenario, explaining the difference
between syntax and semantics.
Philosophy: Philosophy of Mind (AH)
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4.
THE PROBLEM OF PERSONAL IDENTITY
Introduction
Consider the changes, both physical and mental, that a human being undergoes
throughout the course of his/her life. We are inclined to think that the human being
who passes from embryo, to newborn child, to adolescent, through to young
adulthood, middle age, and eventually old age, remains the same human being
throughout his/her life. And we usually say that the human being remains the same
person throughout his/her lifetime. For example, we say that John Smith was born on
such and such a day, eventually graduated from kindergarten with flying colours,
went on to marry so and so, and eventually died after a long and eventful life. But
what justifies these views? What is it that remains the same throughout the life of a
human being that allows us to say that this human being is the same person? Clearly
the physical and mental properties exhibited by the human being at each stage of
development are so markedly different that these alone cannot account for our view
that it is one and the same person who has had these physical and mental
characteristics.
Stating the Problem of Personal Identity is, therefore, quite straightforward.
Informally, we want to know what it is that makes us the same person we were last
week, the same person we were a year ago, etc., and what needs to remain constant
about us to remain the same person next week, next year, etc. Stated more formally,
philosophers are looking for an answer the following question:
What makes a given person at time t1 the same person at time t2?
In other words, we are looking for the Criterion of Personal Identity.
The reason for attempting to answer this question is the expectation that in so doing
we will throw light on the notion of ‘personhood’. The notion of personhood is
interesting because we tend to value persons above non-persons, and so to treat
persons differently from non-persons. We value ourselves first and foremost, and
then our nearest and dearest. This concern for the welfare of our own person and our
family and friends shows itself most clearly in times of crisis, particularly in times of
serious illness and death. But the existential-religious import of the notion of the
person extends into the moral realm of daily life as well. We find Kant, for example,
teaching that we should treat persons as ends in themselves and not merely as means.
Being a person also entitles one to various rights. Being able to claim the title of
‘person’ then is no insignificant matter.
But why do we value persons above non-persons? Is this a defensible position? What
is the relation between being a person and being a human being? Can you be human
but not a person or a person but not human? Just what is it to be a person anyway?
These are the issues at the heart of the personal identity problem, and it is hoped that
some progress can be made on them if we can get a defensible answer to the rather
formal question posed above.
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There are three theories of personal identity to be discussed here:
i)
The Soul Theory (or Criterion)
ii)
the Body/Brain Criterion and
iii)
the Psychological Continuity Theory.
Each has more or less obvious links to positions developed in the Mind/Body
Problem.
Philosophy: Philosophy of Mind (AH)
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The Soul Criterion
The Soul Criterion stipulates that if x at time t1 has the same soul as y at time t2, then x
and y are the same person. Consequently, to be a person is to have a soul.
Historically souls have been characterised as non-physical substances, and so the
connection between this Theory of Personal Identity and Descartes’ Substance
Dualism is clear enough.
Given the now well-known difficulties facing Substance Dualism, and the general
decline in prestige of various religious faiths, the Soul Theory is not particularly well
regarded within the philosophical community. That said, the Soul Theory does have a
grand philosophical tradition (going back to Plato at least), and it does play an
important role in the formulation of various religious doctrines which still attract
adherents. The doctrines of the immortality of the soul, reincarnation, and karma
presuppose some form of radical Dualism between mind and body, and some version
of the Soul Theory. Moreover, some philosophers have tried quite recently to
resurrect Substance Dualism (see William Hart’s, The Engines of the Soul, CUP,
1988) and if successful, this would enhance the credibility of the Soul Theory. It is
worthwhile then to examine the strengths and weaknesses of this position.
Arguments in favour of the Soul Criterion
1)
As we saw in the case of the Mind/Body Problem, a position can often appear to
be the least objectionable on offer, and so be adopted faute de mieux. As we
shall see, all the theories to be examined face some difficulties. Some might
think that the difficulties of the alternatives are enough to lend credibility to the
Soul Theory. Indeed the difficulties of the alternatives have been deemed
serious enough by some to warrant the suggestion that the notion of personal
identity should be dropped altogether and replaced by the notion of the ‘closest
continuer’. Some might recoil from this option, thinking that Substance
Dualism is not so bad after all.
2)
The Soul Theory also makes sense of some of our intuitions about persons. If a
person is a soul, and the soul is given a traditional interpretation (i.e. one
embedded in a religious context) then we have an explanation and a justification
for valuing persons over non-persons.
Philosophy: Philosophy of Mind (AH)
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Problems with the Soul Criterion
1)
As noted above, all versions of the Soul Criterion must accept some form of
Substance Dualism. Consequently, the Soul Criterion inherits all the difficulties
of Substance Dualism.
2)
If the Soul Theory suffers from its links with Substance Dualism, its links to
various religious doctrines have not proved helpful either. The Soul Theory is
an essential component of the doctrines of immortality and reincarnation, and
both of these present fresh problems. If neither is coherent or plausible, then the
Soul Theory suffers by association. (Guilt by association)
Consider the immortality of the soul. According to this doctrine, after death the
material body and immaterial separate, bringing about the dissolution of the
human being. The material body then returns to dust and ashes, while the soul
goes on to enjoy a disembodied existence.
Many philosophers have argued that the notion of non-bodily existence and
experience is simply incoherent. But it must be said that this view presupposes
the truth of some form of Materialism. By Materialism’s lights, one’s mental
capacities are determined by the nature of one’s brain and nervous system, the
mental being at the very least supervenient upon, if not reducible to states of
brains. This view is also supported by the fact that an organism’s mental
capacities increase as the complexity of its brain increases. The mental life of
the human is far richer than the mental life of a rat because of the superior
complexity of the brain of the former. If all this is true, then it is plausible that
there can be no soul without a physical body, and no experience without the
physical organs of perception.
The Dualist/Soul Theorist can respond by stating that all that has been
established by the brain sciences is a correlation between mental activity and
brain states. For every mental event there is corresponding brain event. This
the Dualist can happily concede. But this does not prove that minds are
reducible to brains, or even that they supervene on brains. The model they
provide is that of the musician playing an instrument. Just as a musician can
play one instrument after another – the sounds produced on each occasion being
determined in large part by the properties of the various instruments – so too the
soul can pick up a new body, and modify its behaviour according to the brain it
happens to be using (this image recurs in the doctrine of reincarnation).
As for disembodied experiences, the Dualist can appeal to a form of telepathic
experience, something akin to the communication once thought to obtain
between angels in the middle ages.
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3)
In philosophy one rarely finds arguments which are definitive and conclusive.
Even the most implausible views can be defended if one is willing to believe
other equally improbable things. The Soul Theory is a case in point, as we
began to see in the last paragraph. It might not be incoherent in and of itself
(even the problem of causal interaction can be met if one is willing to accept
Occasionalism or Leibniz’ Pre-established Harmony.) Nonetheless a theory can
be criticised if there is little empirical evidence for it. The evidence for the
doctrines of reincarnation and the immortality of the soul is weak indeed.
Consider the experiences brought forward in support of reincarnation (déja vu,
child prodigies, ‘past life’ memories, ‘out of body’ experiences). There is no
doubt that such phenomena do occur. What is at issue is how they are
understood. And it is far from obvious that the Soul Theory alone can account
for these experiences. Indeed for many of these experiences alternative,
materialist explanations can be provided. And given the still embryonic state of
brain science, it is not unreasonable to think that explanations for the as yet
unexplained will be forthcoming. So the fact that the meagre empirical
evidence in favour of the Soul Theory can itself be accommodated by nondualist theories shifts the balance of probabilities against the Soul Theory.
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The Body/Brain Criterion
If the Soul Criterion sits well with Substance Dualism, then the Body/Brain Criterion
of Personal Identity is the obvious counterpart to materialist approaches to the
Mind/Body Problem. According to this view if x at time t1 has the same body as y at
time t2, then x and y are the same person.
Arguments in favour of Body/Brain Criterion
1)
This view has the advantage of avoiding the troubles of Substance Dualism, and
some of the counter-intuitive results of the Psychological Continuity Theory to
be discussed below.
2)
As a matter of fact we usually do identify persons over time simply by noting
the continuity of their physical appearance (they have the same bodies as they
had last week).
Problems with the Body/Brain Criterion
1)
Cells of the body are continually dying and being replaced. Indeed, after 7
years every cell in the body has died and been replaced by a functionally
identical cell (if we are lucky). So, the body we have today shares no matter
with the body we had 7 years ago. Yet we do think we are the same person we
were 7 years ago. Ergo, etc. The case is even worse if we remember that the
embryo, at least in the early stages, does not even have all the body parts a
human will have at a later stage of development. Perhaps we are not yet
persons?
2)
It is obvious that the person cannot be identified with the whole body. For
instance, if someone is unfortunate enough to be forced to have a limb
amputated, we do not thereby conclude that the amputee is no longer the same
person they were before the operation. No doubt they will be ‘changed’ in more
than their physical endowments, perhaps elements of their personality will come
to the fore that were hidden or under-expressed. But changes of this sort are not
enough to say that we are now faced with an entirely new person. ‘Change’
presupposes a continuity at some level, while ‘replacement’ implies novelty of
an entirely different order, i.e., something entirely new.
Nonetheless, some part of the body, usually the brain, could still be absolutely
essential for the continuity of the person. Perhaps the most famous thought
experiment to support this view is the brain transplant case involving the
fictional figures of Brown and Robinson. Neither Robinson nor Brown is in the
best of health. In fact Robinson’s brain has had to be removed, and his skull is
empty. Brown’s brain, on the other hand, is fine, but his body is not.
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Doctors decide to surgically implant Brown’s healthy brain into Robinson’s
empty skull.
Which person, Brown or Robinson, do we have when the procedure is
completed?
Most accept that it is more plausible to say that Brown has had a body
transplant, rather than that Robinson has had a brain transplant, i.e., that it is
Brown who ‘survives’ the operation.
3)
Continuing with the Brown-Robinson case – while most agree that it is Brown
who survives the operation, there is some disagreement about why this is so.
Clearly proponents of the Brain Criterion maintain that it is because the brain of
Brown survives. But proponents of the Psychological Continuity Theory
suggest that what is really behind this intuition is that Brown’s memories,
character traits, and personality survive, and that it is this point, rather than the
survival of the brain itself, that justifies the conclusion that Brown has survived.
On this view the brain is merely the accidental ‘carrier’ of Brown’s
psychological makeup, the latter being essential to the person.
At this point a word of warning is perhaps in order. As we have just seen, thought
experiments figure prominently in the debates about personal identity. These thought
experiments, which often trade on ‘Star Trek’-like science fiction scenarios, are
designed to tease out our intuitions about what constitutes a person. We are asked to
consider ‘what we would say’ in such circumstances, whether we ‘feel’ that a person
has survived, or whether something essential has been lost. Questions can be asked
about this sort of argumentative strategy.
Firstly, does it matter if these scenarios are physically impossible to realise, at least at
this moment in the history of science? Answer, No. These experiments are entirely
conceptual, and are designed to test the limits of our use of the term ‘person’.
Whether the experiments are science fiction or not is beside the point.
Secondly, and more importantly, what can these experiments establish? What if
intuitions do not match? If I think Robinson survives, and you do not, where do we
go from there? This is a more difficult question to answer. Although intuitions do in
fact match in a large majority of cases, they usually match in those cases which are
fairly familiar, being, if not daily occurrences, then at least quite common. But
science fiction cases are anything but usual, so it is more likely that intuitions will
vary since our use of terms in these new cases are exploratory and tentative. Indeed
we may find that we are unable to say that any person survives these strange
Frankenstein operations. This is precisely what some will argue. Nonetheless, we
can say that these experiments force us to clarify our own thoughts about what
constitutes a person, and that this clarification could not take place without reflection
on ‘weird’ cases.
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The Psychological Continuity Criterion
The most widely discussed Theory of Personal Identity at the moment is the
Psychological Continuity Criterion or Theory which has its origin in Locke’s Essay
Concerning Human Understanding. According to this view, if x at time t1 has the
same set of memories, character traits, personality, skills, etc. as y at time t2, then x
and y are the same person.
As we have seen, this view sits well with those who accept that Brown survives the
Brown-Robinson operation. But it is consistent with both the materialist and dualist
approaches to the philosophy of mind in the sense that one could accept either theory
and embrace the Psychological Continuity Theory. (Locke, for example, was a
Dualist.) In this sense, the Psychological Continuity Theory abstracts from the
substance issue altogether, not unlike the functionalist view of the mind.
This view also has the consequence that the terms ‘person’ and ‘human being’ are not
co-extensive, which means that they do not pick out precisely the same objects in the
real world. Human beings can be, and usually are persons; but the same human being
could end up being two people (at different stages of the life of the human if a radical
discontinuity in their psychological life were to occur – due to amnesia, say, or the
onset of a serious mental illness) or no person at all (a human being in a persistent
vegetative state is still a human being, but no longer a person since there is no psychic
continuity at all). By the same token, this view allows for the possibility of persons
who are not human beings (an alien from Star Trek would count as a person, for
example.)
The theory is usually refined in the following manner. It is impossible to remember
everything that has happened in our lives. Indeed, whole parts of our lives, like our
very early childhood, are a complete blank to us. But is the child of three not the
same person as the young adolescent, even though the adolescent, never mind the
middle aged man, can recall nothing of these early years? To accommodate this
intuition advocates of the Psychological Continuity Theory speak of chains of
memories, rather than one all embracing memory. If the child of four can remember
aspects of his life at age three, and the five year old remembers life as a four year old,
and the adolescent can recall his life at age five, then a chain of memories extending
from the age of three to young adulthood has been forged, despite the fact that the
adolescent can recall nothing of his life as a three year old.
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Considerations in favour of the Psychological Continuity Criterion
In addition to the usual negative arguments, the holder of this theory can claim that it
does do justice to our everyday use of the term ‘person’. We do not identify people
by reference to their soul, and references to similarities in bodies have their
shortcomings as well. But we do think that serious personality changes can often
justify us in saying that so and so is no longer the same person we once knew. If
someone with a recognisable body were to act entirely out of character for a
prolonged period of time, we would begin to look for explanations, such as the
possibility of a long-lost twin, head injuries or mental disorder, even demonic
possession.
Problems with the Psychological Continuity Criterion
1)
We are all familiar now with false memory syndrome - cases where people
report having memories that never happened, that have no basis in their personal
experience. One of the standard complaints with the Psychological Continuity
Theory is that it cannot distinguish true from false memories without begging
the question at issue. How do we know that a memory is true or false if not by
saying that the person claiming to have the memory actually underwent the
experience (if it is a true memory) or in fact did not have the experience (if it is
a false memory)? But this test requires the use of the term person, which is
supposed to be defined by reference to memories. Since the Psychological
Continuity Theory defines the person in terms of memories, it cannot
distinguish between true and false memories.
Defenders of the theory can attempt to make the required distinction without
reference to the notion of person. True memories, on one account, are those that
are caused by the objects and events of which the memory is a report, while
false memories are those brought about in some other fashion. In this way the
distinction can be drawn without relying on the notion of personhood at all.
2)
Even if one accepts that relying on chains of memories is sufficient to preserve
personal identity, the chain does not do back far enough. There simply are no
memories of very early childhood to be linked to any chain. Consequently, we
cannot say that a new-born is the same person as the five-year-old, let alone the
same person as the middle-aged man.
Some are willing to live with this consequence of the theory. Since the notion
of ‘personhood’ is not co-extensive with ‘human being’, this result is not all that
surprising.
3)
Gaps in memory can come in other guises. Consider the senile old man whose
short term memory is, for all intents and purposes, non-existent but who can still
recall accurately events in the long term past. This man does not recall any of
the intermediate links in the memory chain between the events in the distant
past and the present. Does this mean that he is not the same person as the
person whose life he in fact recalls? Or is it that he is identical to that person,
but it was someone else who underwent the experiences that produced the
intermediate links?
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4)
Consider the following Frankenstein operation. Smith’s brain is split, dividing
the brain into its two hemispheres. Each hemisphere contains the same set of
memories, and each is placed into a different empty skull. We began with one
person, Smith, with one brain and one set of memories. What have we now?
Has Smith become two people? Is the original Smith identical to either of the
new entities? By the Psychological Continuity Theory we ought to say that the
person goes where the memories are, and so the original person has become two
new people. But is this credible? How can one thing (the original person) be
identical to two things (the two new entities created by the surgery)? And does
it make sense to say that Smith still exists as all?
Some argue that neither of the new entities can be identical to the original
person because identity relations cannot hold between three entities (Smith, and
the two halves of Smith’s brain). Rather than being the identical to the original
person, the two new entities are merely duplicates of the original and that the
original did not survive the operation.
5)
The notion of personhood as we noted above is linked to issues of concern. We
are concerned about ourselves first and foremost, and then about the welfare of
our nearest and dearest (who are also persons). But can the Psychological
Continuity Theory do justice to this concern?
Imagine the following case: You are told that you are dying of a terminal
illness. However, doctors can now ‘download’ your personality from your brain
onto computer disk and infuse this personality into an android (a bit like Data
from Star Trek). Nothing of your original body would remain, but your
memories and personality would survive in the android. Would you accept this
procedure? If your partner or child decided to undergo this procedure would you
feel that the android was your partner or child?
Consider another case: You have been found guilty of a serious offence and are
forced to choose between two possible punishments. The first option is a quick
and painless death. The second is a slow death by torture, but only after total
amnesia has been induced. The Psychological Continuity Theory, if correct,
would encourage one to choose the second option, since you would not suffer
the torture because of the induced amnesia. But intuitions don’t usually agree
with this choice. A quick painless death seems preferable to many. This
suggests that there is more to the notion of personhood than psychological
continuity, and that there is something fundamentally important about the
continuity of the body.
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Final Suggestion
Some have thought that the inability to find the Criterion of Personal Identity invites
the conclusion that the whole notion of personhood is an illusion, a notion with
nothing answering to it in the real world. Indeed, if something exists, we ought to be
able to provide clearly stated identity conditions. If we can’t provide these, goes the
story, then we don’t really know what we are talking about. To know what you are
talking about requires that you can distinguish the object of your conversation from
everything else, and we usually do this by providing the object’s identity conditions.
Since we have failed to provide the identity conditions of ‘person’ we don’t really
know what we are talking about. And the conclusion to draw from this is that persons
are really fictions, not real features of the world.
We won’t go into this argument here. But it is clear that the theories on offer have not
proved entirely satisfactory. But is there any reason to think that these criteria are
mutually exclusive? Could it be that a combination of brain and psychological
continuity together capture our intuitive notion of personhood?
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Student Activities
1. Give an account of the Problem of Personal Identity.
2. What do you make of the soul theory?
Keep in mind the fact that no theory is without serious objections.
3. Are you in essence: your brain, the contents of your brain, or both?
Is one of these elements more important than the other?
4. What is the Brown-Robinson case?
What does this thought experiment establish in your view?
5. How might we distinguish between true and false memories?
What hangs on being able to make the distinction without reference to persons?
How might this be done?
6. Do you think you would survive in any meaningful sense if your brain were split
in two, each placed in an empty skull?
7. What is the point behind all the ‘Frankenstein’ thought experiments?
Does this matter if these scenarios are impossible to realise?
8. If we cannot find the Criterion of Personal Identity does this mean that the notion
of the person is an illusion?
What would be the implications of denying the existence of persons?
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5.
FURTHER READING
Most introductory texts in philosophy will have chapters on the two topics covered in
this unit. The following more specialised texts are also very useful:
A Companion to the Philosophy of Mind Guttenplan, Ed. Oxford: Blackwell’s, 1994.
A Companion to Metaphysics Kim and Sosa, Eds. Oxford: Blackwell’s, 1995.
(Both of these are highly recommended. They cover all topics discussed in this
unit and others. They also provide extensive reading lists after each entry.)
Philosophy of Mind: An Overview for Cognitive Science William Bechtel, London:
Lawrence Erlbaum Associates, 1988.
(This is intended as an introduction to the Philosophy of Mind for specialists in
the cognitive sciences. It is a good general introduction; but it also puts the
Philosophy of Mind in a wider context by showing its connections to the
cognitive sciences.)
The Philosophy of Mind: An Introduction Smith and Jones, Cambridge University
Press, 1986.
(Smith and Jones defend a particular theory in the philosophy of mind – a type
of Functionalism inspired by Aristotle – but provide good accounts and
criticisms of other theories, particularly Dualism and Behaviourism.)
“Philosophy and life after death: the questions and the options” in Philosophy of
Religion: A Guide and Anthology Steven Davis, Ed. Oxford: OUP, 2000.
(Particularly useful on the connections between the Mind/Body Problem and
Personal Identity in the broader context of the debate concerning the possibility
of life after death. Also contains lengthy and detailed discussions of all the
arguments for the existence of God.)
Philosophical Propositions: an Introduction to Philosophy Johnathan Westphal,
London: Routledge, 1998.
(The chapter on Personal Identity is useful.)
An Introduction to Philosophical Analysis John Hospers, London: Routledge, any
edition.
(Contains useful material on the Problem of Personal Identity – and other
matters – including a lot of thought experiments which might be useful for
classroom exercises.)
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