P A R T I
P H I l 0 S 0 P H Y
INTRODUCTION
Welcome to philosophy. For some of you, it will be the most practical subject you will
study in college.

Why would we say that? Doesn't philosophy have a reputation for being impractical?
Isn't it abstract and theoretical-the very opposite of practical?

Philosophy can be abstract and theoretical. But the study of philosophy can be practical
in that it affects what you do with your life. This is because the abstractions and theories
pertain to the basic concepts and values with which you confront experience.

Humans do things for reasons. We want certain things, and we believe that acting in
certain ways will get us those things. So we act. Rocks don't act for reasons, but we do. It's
part of what makes us human. Our desires and beliefs provide us with those reasons. Values
and concepts are the building blocks of desires and beliefs. Thus our values and concepts
play a big role in determining what we do and who we are.

Humans also reflect on and criticize the reasons we do things. Do we have good reasons
for our reasons? Why do we want what we want? Why do we believe what we believe?

Having the capacity to reflect on one's reasons is another part of being human. It's a
capacity that divides us from most of our fellow animals. We not only believe things, we
can think about why we believe things. We not only want things, we can ask ourselves
why we want them.

All humans have this capacity to reflect on their beliefs and desires, on their basic con-
cepts and values. But not everyone likes to do so. It is the love of this activity that draws a
person to philosophy. Do you worry about whether there is a God? What the difference
between the future and the past is? Why we can't turn around in time as we can in space?
Whether you are really a brain in a vat in someone's experiment? Whether other humans
have minds, or just you? How you would know if blue things looked to you just like green
things look to everyone else? How you can be free, if every physical event has a physical
cause? Have you ever wondered what made it wrong to lie and cheat? Whether democracy
was really better than other political systems, or just the one you happened to grow up in?
If this all sounds like you, taking a philosophy course may be one of the most enjoyable and
most liberating experiences of your life.

Why should reflecting on one's beliefs and desires be liberating? Because in a very real
sense your beliefs and desires, because they motivate what you do, define who you are. But where did those desires, values, and beliefs come from? Are they merely the accidental
result of where you were born, who your parents and teachers and friends were? Philosophy
can be liberating because it helps us reflect on the basic concepts with which we deal with
experience and the desires that motivate us to do what we do, and to put our personal stamp
on them. We can never fully escape limitations on our vision that result from the particular
time and place in which we live. But through reading and thinking we can examine and
challenge ideas that seem natural from our perspective with ideas that come from quite
different points of view. Those of our values and concepts that survive this process will be
more truly our own.

While college may seem like a hectic time, it is the best opportunity that most of us have
to reflect intensively on who we are, to examine the source of our own way of looking at
things, and seriously to consider alternatives. One of the saddest things that can happen to
a person is to realize that she has committed a large part of her life to goals that upon reflec-
tion don’t seem very important, on the basis of beliefs that upon reflection don't seem very
plausible. Because your philosophy class gives you tools and opportunity to reflect on your
basic values and concepts, and to develop habits of reflection, it may be the most practical
course you take in college.

The philosophy class in which you are enrolled, and for which this book is a text, is part
of a long tradition, stretching back to ancient times, of reflecting on the most basic values
and beliefs that humans have. Philosophy means thinking as hard and as clearly as one can
about some of the most interesting and enduring problems that human minds have ever
encountered. Some of these problems have been discussed since ancient times. What makes
acts right or wrong? You can read what the ancient philosopher Plato, the eighteenth-
century philosopher David Hume, and the contemporary philosopher Tom Nagel have to
say about it. What is it to be conscious? You can read what the seventeenth-century
philosopher René Descartes, the pioneer of computer theory Alan Turing, and the contem-
porary philosopher Iohn Searle think about that. Other problems are as timely as your
morning paper. Is there anything wrong with a woman renting out her body? You can

read what Debra Satz thinks about that. Is it immoral to get an abortion? You can read
what Rosalind Hursthouse and Judith Thomson say about that.

To read philosophy well one must read slowly and aggressively. This may mean breako
ing some habits. There is a lot of emphasis today on reading fast. This is the age of informa-
tion. To take advantage of the information available to us (even to cope with it) or to master
that which is important for our job, for responsible citizenship, or for a full life-or at any
rate for the final or the midterm-you have to learn to absorb large amounts of information
in limited amounts of time. The college student, one hears, must learn to read at a mini-
mum of 1000 words a minute. And 2000 or 3000 words is better; and those who really want
to get ahead should read so fast that the only limiting factor in the speed with which they
read is the speed with which they can turn pages.

These skills may be suitable for some types of reading, but not for philosophy. Good
philosophers develop arguments and theories of some intricacy: arguments that are de-
signed to convince the reader of the author's position on important issues. Reading such
works is valuable insofar as one grapples with the ideas-not only fighting to understand
the author but also, once one does, fighting with him or her for control of one’s mind. One

should not be easily convinced of one position or another on issues so weighty as the exist-

ence of God, the indirectness of our knowledge of the external world, or the nature
of justice.

Of course, all generalizations are a bit suspect. When one is reading for pleasure or to
absorb straightforward information from a reliable source, speed-reading can be fine. But,
if one derives pleasure from reading philosophy, it should be the pleasure of grappling with
important and sublime ideas, not the exhilaration of racing through a thriller. And, when
one learns from reading philosophy, it should be a result of being forced to think through
new ideas and grasp new concepts, not simply the uploading of a data file from the text to
the mind.

College students will have learned that mathematics and other technical material
cannot be read in overdrive. But philosophy can be deceptive. It cannot be claimed that
good philosophy always makes good reading, but some philosophy does. A lot of philoso-
phy, including a good portion of the famous historical works included in this anthology,
makes pleasant reading. It does not contain symbols, equations, charts, or other obvious
signs of technicality and intricacy. One can just sit down and read Hume, or even Descartes,
getting a feel for the author’s position and style and the historical perspective of the work.
When these texts are assigned in courses that survey the literature of various periods-
with an eye toward getting a sense of the flow of ideas and concerns-as parts of larger
assignments that cover hundreds of pages a week, one may have little choice but to read
philosophy in this way, that is, just to get a feel for what is going on.

But appearances to the contrary, philosophy is inevitably technical. The philosopher
constructs arguments, theories, positions, or criticisms in an attempt to persuade his or her
most intelligent and perceptive opponents. The ideas and issues dealt with have a long his-
tory: to say something new, interesting, and persuasive, the philosopher must build his or
her case with care. The result may be understood on various levels; to understand it at the
deepest level, the reader must adopt the stance of the intelligent and perceptive opponent,
thus coming to understand the case the philosopher is trying to make. This is what we mean
by reading aggressively.

To read philosophy in this way, one should imagine onself in a dialogue with the
philosopher-as if the philosopher were one’s roommate (or an intelligent and articulate
new roommate) trying to convince one of a startling new idea.

To see this approach at work, let’s consider an example. Here is a passage from Desca rtes's
“First Meditation.”

Today, then having rid myself of worries and having arranged for some peace
and quiet, I withdraw alone, free at last earnestly and wholeheartedly to over-
throw all my beliefs.

To do this, I do not need to show each of my beliefs to be false; I may never
be able to do that. But, since reason now convinces me that I ought to with-
hold my assent just as carefully from what is not obviously certain and indu-
bitable as from what is obviously false, I can justify the rejection of all my
beliefs if I can find some ground for doubt in each. And, to do this, I need not
take on the endless task of running through my beliefs one by one: since a
building collapses when its foundation is cut out from under it, I will go straight
to the principles on which all my former beliefs rested.

Let’s start with the second paragraph. The first place to pause is the word this. Whenever

one encounters a demonstrative pronoun or other device by which the author refers back to
something earlier, one should pause and make sure one knows to what it refers. DESCAR'I’ES: To do this
YOU: Wait a minute. To do what? Oh yes, I see, to overthrow all your beliefs.

But what is to overthrow one’s beliefs? This sort of phrase ought immediately to occasion a
demand for clarification.

Y: What do you mean, “Overthrow all your beliefs” anyway? Every one of them? You

must be kidding? You are trying to make yourself believe everything you now believe
is false? Can that really be what you mean?

Of course, Descartes isn’t your roommate and, in fact, is long dead. So he can’t respond to
you. Still, you should mentally-or on the margin of your book-note this question.

Y: Well, ofcourse you can't respond. But this sounds pretty odd. I will keep my eye open
for clarification ofjust what it is you are trying to do.

D: As I was saying: To do this, I do not need to show each of my beliefs to be false; I may
never be able to do that.

Y: Well, I didn't have to wait long. It’s a relief that you aren’t going to show all of your
beliefs to be false. Still, it sounds as ifthis is something you want to do but simply don’t
think you could. The point of even wanting to seems a bit obscure. Go ahead.

I): But, since reason now convinces me

Y: Reason. Reason. I wonder what exactly you mean by that. Hmm, this is the first use
of the word. I mean, I know the meaning of the word reason, but it sounds as if you
have something rather definite in mind. Actually, I use the word as a verb rather than
a noun. Maybe I had better look it up in the dictionary. Here we are: “A statement
offered in explanation." That doesn’t seem to fit. Motive, cause, likewise. Sanity. That
must be as in, “He has lost his reason." ()r intelligence. One of these must be the closest.
The latter seems better. So you are saying that your intelligence convinces you that you
should be a great deal more cautious about what you believe-that’s what this seems
to amount to. Still, I have a hunch that more is packed into your use ofthe word reason
than I can get out of the dictionary. The prof said you were a rationalist and that they
put great emphasis on the power of reason. I’ll keep it in mind that this is a key word
and look for other clues as to exactly what you mean by it.

I): . . . That l ought to withhold my assent just as carefully from what is not obviously
certain and indubitable as from what is obviously false; I can justify the rejection ofall
my beliefs if! can find some ground for doubt in each.

Y: Wait a minute. You just said a mouthful. Let me try to sort it out. Let's see. Withheld
my assent. So you said you were going to overthrow your beliefs at the end of the last
paragraph. Then, you said to do this you don't need to show that they are false. So
withholding assent must be how you describe the in-between position-you have quit
believing something, and although you haven't shown it false, you don't believe the
opposite either.

Wait a minute. Does that make sense? lfl don't believe that 3 + 5 = 8, don't I
automatically believe that it's not the case that 3 + 5 = 8? Hmm. I guess not. Suppose
it was 358 + 267. Until I add it up, l neither believe it does equal 625 nor believe that it
doesn't. So I guess that's where one is at when one is withholding assent. Here is another mouthful: “Not obviously certain and indubitable.” I’ll look up the
last word. Unquestionable: Too evident to be doubted. How is that different from cer-
tain? If your Meditations is one ofthe all-time classics, why are you being redundant in
this show-offy way? Maybe I should give you the benefit ofthe doubt.

Let’s see, the contrast is between certain and indubitable-no, wait, obviously cer-
tain and indubitable-and obviously false. Clearly one withholds one's assent from
what is obviously false. So what you are saying is that you are going to do the same
for everything, except that which is obviously certain and indubitable. And your rea-
son, which seems to amount to your intelligence, is what leads you to do this. OK,
proceed.

D: . . . I can justify the rejection ofall my beliefs

Y: You seem to go back and forth between a pretty sensible position-not believing what
you aren't really sure of-and something that sounds a bit weird. Before you said you
were going to try to overthrow all your beliefs; now you are trying to justify rejecting
all your beliefs. I must admit, even though you have quite a reputation as a philosopher,
this project strikes me as sort ofextreme.

D: . . . lfl can find some ground for doubt in each

Y: Oh dear, another technical sounding phrase: ground for doubt. I better pull out my
Webster's again. Well, you aren’t using ground to mean dirt and you don’t mean the
bottom of a body of water, so you must mean basis for belief or argument. I t sounds as if
you are going to look for some basis for an argument against every single one of your
beliefs. That sounds like quite a project. I wonder how come your Meditation: is so short
if you are really going to go through each one of your beliefs.

I): And, to do this, I need not take on the endless task of running through my beliefs one

byone...

Y: Well, that’s a relief.
I): . . . Since a building collapses when its foundation is cut out from under it, I will go

straight to the principles on which all my former beliefs rested.

Y: Relying on a metaphor at a crucial point, eh? I thought the profsaid that was a dubious
practice. She said we should look at the assumptions underlying the appropriateness
of the metaphor. So it looks like you think your beliefs form a structure with a founda-
tion. The foundation is principles. All your beliefs rest on-i.e., I suppose, depend on
in some way-certain principles. For this all to make sense, these principles must be
beliefs. So what you are saying is that you are going to isolate certain beliefs, on which
the rest depend. lfyou have a ground for doubt for a principle, you will quit believing
it, not in the sense of taking it to be false or believing the opposite, but in the sense of
withholding your assent. In so doing, you will automatically have a ground for doubt
for all other beliefs that depend on the dubious principle.

Well, I guess that's an intelligible project. It still seems like it ought to take a lot
longer than 30 pages. We shall see

This is what it is like to read aggressively.

But being part of the philosophy tradition doesn’t just mean reading about what others
have thought. It means thinking yourself. long and hard, about the problems that interest
you, and writing about them.you are joining a tradition that goes back to Hume and Descartes and Aristotle and Plato.
We have invited you to think about big issues and basic concepts. But when you get your
writing assignments, your teacher will no doubt warn you against trying to be too deep and
profound.

Imagine going to the ballet. You are impressed with the ballerina, and decide that you
want to become one. The day of your first ballet lesson arrives. You have visions of a whole
new world opening up to you; you imagine yoUrself gliding across the floor, spinning,

jumping. But you find that your ballet lesson isn’t like that at all. You spend a lot of time
stretching and doing other exercises that

Swan Lake.

Your first experience writing philosophy is going to be like that. You have read sdme of
the works of the great philosophers. You are eager to share with the world some of your
own deep philosophical thoughts, and to attack head on some big problems. But what you
will be asked to do, in all likelihood, is to write a very short and very clear essay on a very

restricted topic. And when your teacher grades the essay, she may miss all the profundity

and focus on the fact that you didn’t state with absolute clarity some mundane things she
should have known anyway.

you don’t remember anyone doing when you saw


through the same thing.
Here are some of the skills you need to master to do well in philosophy:

0 Analyzing statements and arguments.

When you were working to understand Descartes in the passage we went through ear-
lier, you were analyzing his statements. You were making sure you understood each word,
and knew the possible ambiguities.

In a good philosophical essay the statements will add up to arguments, with premises
and a conclusion. (For more about arguments, see the entry deductive argument in the glos-

sary and the related entries.) You need to learn to spot the main conclusions the philosopher
is arguing for, and the premises she uses to establish them.

0 Imagining alternatives to familiar views and situations.

Nothing is more important to a philosopher than a good imagination. If you encounter
a generalization, you should try to see if you can think of a counterexample. If you encoun-

ter a view that seems strange or absurd, you should try to see if you can imagine what ex-
periences would lead someone to hold that view.

0 Stating things explicitly. clearly. and succinctly.Saint Paul said, “Faith, Hope and Charity, but the greatest of these is Charity." As a novice
philosopher, your motto should be “Truth, Profundity, Clarity, but the greatest of these is
Clarity.” The reason is this. Our language is built around familiar ideas and situations. Phi-
losophers often need to express thoughts that push the limits of language, because they want
to consider unfamiliar ideas and odd situations. When doing this, it’s relatively easy to sound
profound, but very difficult to be clear. But if you are not clear, you cannot be sure that what
you say is true, nor can you get the help of others to figure out whether it is’.

Looking constantly for concrete examples that nail down what you are getting at is one
of the best ways of keeping your thinking and writing clear. Another is to imagine a reader
of your own work, who is reading it as slowly and aggressively as we encouraged you to read
the philosophical works you encounter. Indeed, don’t just imagine such a reader, become
such a reader, rooting out unclarity and ambiguity in your own work.

0 Thinking creatively.

A lot of philosophy is analysis and criticism: criticism of the concepts and values you
inherit, criticism of the ideas you encounter in the work of others. and criticism of your own
ideas. But one of the most important values of the philosophical tradition has been the new
concepts and values that emerge from the stubborn reflection on old ones. At the beginning
of virtually every social and scientific revolution, there stands a philosopher who not only
questioned some idea or practice of her age, but was able to suggest something better.

If you can develop these skills as a philosophy student, then there is another way in
which philosophy may be a very practical pursuit for you. Most professions highly value
persons who can carry the analysis of a position or an argument to a deeper level, who can
identify and untangle assumptions, and who can communicate effectively about compli-
cated matters. Our world is a world replete with documents, deliberations, and decisions.
The person who can bring rigor, clarity, and imagination to bear on dealing with these
documents, deliberations, and decisions can make an enormous contribution in any number
of areas of life.

In all these senses, then, philosophy can be a practical pursuit for the college student.
Our fondest hope for this book is that it encourages those students with a bent toward re-
flection to plunge into philosophy and to reap the rewards its study can bring. Logic and Philosophy

Philosophy is very much about asking questions.
Does God exist? What can we know? What keeps
us the same through time and change? Is the mind
distinct from the body? How do we know what is
right and what is wrong? Because not everyone is
going to agree on the correct answers to these ques-
tions, it is extremely important to give reasons why
you think one answer is better than another. In
giving reasons why you believe (or why others
should believe) a particular answer, you are doing
logic, even though you might not recognize it as
such. Logic is just a way of articulating more clearly
the reasoning that we ordinarily do when we tell
someone why we believe something.

If we are to be persuaded that your position is
correct, we need to have some way of assessing the
reasons that you give for believing your position. For
instance, we need to know whether your reasons re-
ally do lend support to the position. This is where
learning a bit of logical apparatus can come in quite
handy. So let's introduce some terminology.

Arguments

We’ll start with the basic idea of an argument. As we
use the term in philosophy, an argument is not just a
verbal dispute about some matter. Rather, it is a way
ofarticulating reasons. Or, to be more precise:

An argument is a series of statements where the last
statement supposedly follows from or is supported by
the first statements. The last statement is called the

conclusion, and the first statements are called the
premises.Here’s a relatively simple example:

1. Everyone who lives in Los Angeles lives in
California.

2. Alvin lives in Los Angeles.

3. Therefore, Alvin lives in California.

Suppose we were trying to convince you that our
friend Alvin lives in California. (Again, we probably
wouldn’t normally give you an argument to con-
vince you of this, but this is a simple example just to
get the idea of an argument under our belts.) We
might give you the following reasons for believing
that Alvin lives in California. First, we know that
Alvin lives in Los Angeles. And second, we know
that Los Angeles is in California, so anyone who
lives in Los Angeles automatically lives in California.
These two reasons are represented by premises 1 and
2, and they are meant to support the conclusion,
which is number 3. Arguments in the articles that
you read for class will most often not appear in this
numbered form, but they can all be reconstructed in
this form so that the reasoning is easy to see.

In this example, if you were to accept the two
premises, you would have to accept the conclusion.

So our argument is, in a certain sense, a good argu-
ment. But there are different ways that an argument

can be good.
Validity

The first way an argument can be good is if its

premises actually do support its conclusion. Recall
that our definition of an argument is a series of state-

ments in which the conclusion supposedly follows
from or is supported by the premises. Well, there are some arguments with conclusions that actually do
follow from the premises, and there are some argu-
ments with conclusions that don’t actually follow
from the premises, even though they supposedly do.
The first type of arguments are valid arguments,
and the second type are invalid arguments. Or, a bit

more carefully:

An argument is valid if its conclusion follows from
its premises.

Or, more carefully still:

An argument is valid ifit satisfies the following con-
dition: If its premises were true, then its conclusion
would Izavc’ to be true.

The argument we gave previously is an example of
a valid argument because if premises 1 and 2 were
true, then 3 would have to be true. But the following
is an example of an invalid argument:

1. Everyone who lives in Los Angeles lives in
California.

2. Alvin lives in California.
3. Therefore, Alvin lives in Los Angeles.

If we were to put forth this argument while trying
to convince you that our friend Alvin lives in Los
Angeles, you shouldn’t be convinced. Why not?
Simply because the reasons that we gave for believ-
ing that Alvin lives in Los Angeles don’t actually
support that conclusion. For in this case, premise 1
could be true (it actually is true), and premise 2
could be true, but the conclusion might still be false
(Alvin could live in San Francisco, for instance).
Thus this is an invalid argument. The conclusion
doesn’t actually follow from the premises. It’s not
the case that if its premises were true, then its con-
clusion would have to be true.

In philosophy, as in life, we’re mostly inter-
ested in putting forth valid arguments. At the
very least, our conclusions must really follow
from our premises. But although validity is a good
first step, it’s not the only way that an argument
can be good.Soundness

If we succeed in putting forth a valid argument,
that’s a good start. But we want more from our ar-
guments. We also want our premises to actually be
true. Recall that validity was about the relationship
between premises and conclusion: If the premises
were true, then the conclusion would have to be
true. But sometimes that’s a big “if.” That is, some-
times we’re not sure whether the premises are actu-
ally true. That's the next thing we care about. [four
argument is valid and its premises are also true, then
the argument is sound. More precisely:

An argument is sound if it is valid and has all true
premises.

Or, more precisely still:

An argument is sound if it satisfies the following two
conditions:

I. It is valid.
2. All of its premises are true.

Let us give another example to understand sound-
ness better. Consider the following argument:

1. Abortion is the killing of an innocent person.
2. Killing innocent people is morally objection-

able.

3. Therefore, abortion is morally objectionable.

This is a much more interesting argument than the
one we gave about our friend Alvin. Indeed, it is
likely to stir emotions. But we're not going to dis-
cuss the moral rightness or wrongness of abortion-
we’re just using this argument as an example so that
we can better understand logic. Now, there are at
least two ways that an argument can be good, so
whenever you are confronted with an argument
such as this, you should always ask yourselves two
questions: First, is it valid? Second, is it sound?
We’ll save you the suspense: This argument is
indeed valid. Remember what that means, though. It
doesn’t mean that abortion is morally objectionable.All it means is that the premises of this argument
really do support the conclusion of the argument. Or,
in other words, if the premises were true, then the
conclusion would have to be true. Whether this ar-
gument is valid is not a matter of controversy. What
is a matter of controversy, however, is whether this
argument is sound. That is, is it a valid argument
with premises that are actually true? This is where
opinions differ. For our purposes, it’s enough to real-
ize that if the premises of this argument actually are
true, then the argument is sound (because it’s also
valid), and if the premises of this argument actually
are false, then the argument is unsound (even though
it’s still valid).

Why do we care about putting forth sound argu-
ments? Well, if you present someone with a valid
argument and you can successfully argue that the
premises of your argument are true, then the other
person must accept the conclusion as well, on pain of
irrationality. Because valid arguments are such that
their conclusions really do follow from their prem-
ises, one cannot accept their premises without also
accepting their conclusions. So if you are giving us
your reasons for, say, your belief in God, and you
present us with a valid argument with premises with

which we agree, then we must agree that God exists.
Logic can be a very powerful tool.

Persuasiveness

Although typically soundness is the ultimate goal
for an argument, occasionally that's not enough. For
purposes of illustration, suppose that you believe in
God and your beliefis actually true and you present

an atheist with the following argument for God's
existence:

1. God exists.
2. Therefore, God exists.

iiven our supposition that God actually does exist,
this argument is a sound argument. First, it's valid
because its conclusion actually does follow from its
premise. lfthe premise were true, then the conclu-
sion would have to be true (because they are iden-
ticall). Second, again, given our supposition that God exists, the premise of this argument is true.
So it looks like the argument is sound. But you’re
never going to convince your atheist friend to be-
lieve in God on the basis of this argument. Why
not? Because it’s utterly unpersuasive. Although
it is sound, it commits a logical fallacy, namely,
it’s circular. An argument is circular if its conclu-
sion appears somewhere within its premises. The
reason why no one should be persuaded by a cir-
cular argument is that one would have to already
accept the conclusion of the argument before one
accepted the premises. This gets things backward.
Those who already accept the conclusion will not
need the argument to be persuaded, and those who
do not already accept the conclusion have been
given no reason to accept the premise. A similar,

although more subtle, example is the following
argument:

1. The Bible says that God exists.

2. Everything the Bible says is true.
3. Therefore, God exists.

Suppose again that God does in fact exist, the Bible
says this, and everything the Bible says is true. Given
these suppositions, this is a sound argument. But it's
utterly unpersuasive because one would need to
accept its conclusion before one accepted premise 2.
This is a logical fallacy related to circularity often
called begging the question. An argument begs the
question if one or more of its premises relies for its
truth on the truth ofthe conclusion.

So although validity and soundness are virtues of
arguments, you have to be wary that your argu-

ments are not flawed in some other way, such as by
being circular.

Other Fallacies

It's not always easy to figure out whether a particu-
lar bit of reasoning is valid. In fact, there are some
bits of reasoning that seem to be valid even though
they are not. It will be useful to give a couple of ex-
amples of this phenomenon. A common fallacy of

this sort is called afl‘imu'ng the consequent, illustrated
by the following example:1. If Amelia can vote in the United States, then
A‘melia is 18 years old.

2. Amelia is 18 years old.
3. Therefore, Amelia can vote in the United States.

The first premise of this argument is a conditional-
that is, it is an “if. . . then” statement. The “if“ part of
a conditional is called the antecedent, and the “then"
part of a conditional is called the consequent. Notice
that premise 2 asserts the truth of the consequent of
the conditional in premise 1, and then the argument
concludes that the antecedent is therefore true._This is
why this is called affirming the consequent, and it is an
invalid form of reasoning. It’s probably not too diffi-
cult to see in this simple example that even if premises
1 and 2 are true, the conclusion may still be false. Just
imagine a situation in which Amelia is 18 years old
but is not a citizen of the United States. In that case,
it would still be true that if she can vote in the United
States, she is 18 years old, and it would be true that she
is 18 years old, but it would not be true that she can
vote in the United States. Any argument that takes
this form-a conditional, the consequent affirmed,
and then the antecedent as conclusion-is invalid.

A related fallacy is denying the antecedent. Know-
ing what we know about conditionals, you can prob-
ably guess what this will look like:

1. If Amelia can vote in the United States, then
she is 18 years old.

2. Amelia cannot vote in the United States.

3. Therefore, Amelia is not 18 years old.

Again, we havea conditional in the first premise,
but in this case the second premise is a denial ofthe
antecedent. The argument then concludes that the
consequent must be false as well. But as in the previ-
ous case, this is a fallacious form ofreasoning. Again,
imagine a situation in which Amelia is 18 years old
but is not a citizen of the United States. In that case,
it would still be true that ifshe can vote in the United
States, she is 18 years old, and it would be true that
she cannot vote in the United States, but it would
not be true that she is not 18 years old. And again,
any argument that takes this form-a conditional,
the antecedent denied, and then the consequent
denied as a conclusion-is invalid.These two invalid bits of reasoning seem valid
because they closely resemble two bits of reasoning
that are valid. These are affirming the antecedent and
denying the consequent, and they are illustrated by the
following two arguments:

1. If Amelia can vote in the United States, then

she is 18 years old.
2. Amelia can vote in the United States.

3. Therefore, Amelia is 18 years old.

1. If Amelia can vote in the United States, then

she is 18 years old.
2. Amelia is not 18 years old.
3. Therefore, Amelia cannot vote in the United

States.

These are both valid forms of reasoning. In both
arguments, if premises 1 and 2 were true, then the
conclusion would have to be true. As you can see,
it’s important not to confuse these two bits of valid
reasoning with the fallacious reasoning involved in
affirming the consequent and denying the antecedent.Necessary and Sufficient Conditions

So much for arguments. Another important logi-
cal concept is that of necessary and sufficient condi-
tions. The best way to get a handle on these concepts
is through an example. So consider the following

statement:

If you are a sophomore, then you are an under-
graduate.

This statement is saying that being a sophomore
is sufi‘icicnt for being an undergraduate. In other
words, all you need to be an undergraduate is to be a

sophomore. (But that’s not to say that’s the only way
to be an undergraduate.) In general, a statement of

the form:
If X, Men Y

is a statement that X is a sufficient condition for Y.
Now consider the following statement:If you can vote in the United States. then you are at
least 18 years old.

This statement is saying that being at least 18 years
old is necessary for being able to vote in the United
States. In other words, one of the requirements for
being able to vote in the United States is that you
must be at least 18 years old. (But that's not to say

that that is the only requirement.) In general, a state-
ment of the form:

le, then Y

is a statement that Y is a necessary condition for X.
Occasionally you will come across a statement that

purports to give both necessary and sufficient condi-
tions for something. For example:

You have a sister if and only if you have a female
sibling.

This statement says the same thing as the following
two statements combined:

lfyou have a sister. then you have a female sibling.
lfyou have a female sibling. then you have a sister.

()r, in the language of necessary and sufficient con-
ditions:

Having a sister is necessary and sufficient for having
a female sibling.

Philosophers are often interested in the necessary
and sufficient conditions for some interesting con-
cept, such as knowledge. An interesting philosophi-
cal question is: What are the necessary and sufficient
conditions for the claim that you have knowledge
about some fact? Certainly it is necessary that what
you think you know must actually be true for you to
know it. But is that also sufficient? Probably not, as
you may believe something is true even though you
don't have any good reason to beliexe it, and so on.

A Priori and A Posteriori

It will be useful to have a few more pieces of
philosophical terminology at our disposal. First,philosophers often distinguish between a priori
and a posteriori. These are Latin terms that are
especially useful in describing the way in which
we are able to come to know certain proposi-
tions. Propositions that can be known a priori are
those that can be known completely independent
of experience. They are those propositions that
we can know, so to speak, “from the armchair.”
For example, our knowledge that all triangles
have three sides is a piece of a priori knowledge.
There’s no need to go around the world look-
ing for triangles and counting up their sides to
conclude that all triangles have three sides. On
the other hand, propositions that can be known
a posteriori are those that require experience of
the world to come to know. For example, your
knowledge that it is raining outside right now is
a posteriori knowledge. To determine whether it
is raining, you need to open your eyes and look

at the world. No amount of armchair speculation
will help.

Necessary and Contingent

Another distinction that comes in handy in philoso-
phy is one between necessary and contingent truths.
A necessary truth is a proposition that is true and
could not have been false, whereas a contingent
truth is a proposition that is true but might have
been false. Most of the true propositions we ordi-
narily come across are contingent propositions. For
instance. the fact that you are reading this right
now is a contingent truth. You could very well have
decided to do something else with your time. Even
the fact that you exist is a contingent truth. Had
your pa rents not met when they did, you could very
well have never been born. In fact, we are so sur-
rounded by contingent truths that it's difficult to
think ofan uncontroversial necessary truth. An ex-
ample would be the fact that all triangles have three
sides. No matter how the world could have been.
triangles would always have had three sides-that
statement could not have been false. Of course, we
could have used the word “triangle" to talk about
four-sided figures, but that's not to say that triangles
could have been four-sided figures. The concept of a triangle is so intimately connected up with
the concept of three-sidedness that it's impossible
to have one without the other. Another example is
the fact that all bachelors are unmarried. This is a
necessary truth because no matter how the world
could have been, bachelors would have always been
unmarried.Although these terms are most often used to talk
about true and false propositions, they are also
sometimes used to distinguish between necessary
and contingent existence. You and l exist only
contingentIy-that is, we might not have existed.

God, on many interpretations, is supposed to exist
necessarily-that is, God could not have not existed.Objective

However one judges particular issues in philoso-
phy, there is nonetheless a common thread: philoso-
phy involves the construction and critical analysis
of arguments. (For further discussion, see “Logical
Toolkit.”) Learning how to and refining your ability
to construct and analyze arguments are (arguably,
at least) the ultimate objectives of any philosophy
course. It is, therefore, the purpose of writing a
philosophy paper, because your professor will use
your papers to judge how well you are meeting
the objectives of the course. Showing that you have
comprehended and are able to evaluate the mate-
rial will require you to present your ideas and argu-
ments in a clear, explicit, and organized fashion. You

should be able to do this by adhering to the following
guidelines.

Give Reasons

An argument can be understood as reasons that sup-
port a conclusion. Your number one objective in writ-
ing a philosophy paper should typically be to give
reasons that support the overall point you want to
make. However, although your paper should have an
overall point, or conclusion, you may want to make
several secondary, related points in the body of your
paper. These points should also be backed by reasons.
The idea here is that whenever you make a claim, you
must give reasons that tell your reader why she or he
ought to accept your claim. This amounts to explain-
ing why you have made the claim you have made.
(A very frequent comment made by professors on
students' papers is some variation on “Why?" “Give
reasons," “Support your claims," or “Explain.")Answer the Question

Make sure that you are clear about what the ques-
tion is on which your paper will focus. All too often
students answer what they think the question is, or
discuss what they think the topic is, without ever ad-
dressing the real problem. Addressing the topic and
answering the question requires you to understand
the topic you have chosen and to think carefully about

what you will need to say to clearly explain and eval-
uate the problem.

Organize Your Paper

Your paper should be structured in such a way that
your argument proceeds in an orderly fashion. De-

fending a claim requires giving reasons in support of
that claim, but you can do this in a more or less or-

derly fashion. Among others, two mistakes can lead
to a muddled argument:

1. Announcing a claim and then discussing it at

length before giving any argument in support
of the claim.

Announcing a claim and then discussing vari-
ous other points, claims, or irrelevant issues

before giving reasons that actually support the
claim in question.

h)

Note that a good philosophy paper should involve
consideration of objection: to your views (and the

reasons that supposedly support your views). You
should consider the best objections and evaluate
them. A philosophy paper is kind oflike a “conver-
sation" or a debate in which more than one side is
presented and evaluated. A very frequent mistake made by students is simply to present their opin-
ions and views and perhaps also supporting reasons,
without considering opposing views. A good phi-
losophy paper is not simply a statement ofyour own
views. Also, a good philosophy paper is not solely a
presentation ofone side ofan issue, even ifin the end

you wish to defend a particular view.

Make an Outline

The best way to begin writing your paper is to get
clear on what point you want to make. Then make
a list of the reasons that you think best support each
point. Be prepared to spend some time discussing
these reasons. Sometimes, giving a reason to support
a point requires more than a single sentence.

Stick to the Point

Each paragraph in your paper should have a single
main point that is clearly stated and explained. This
does not mean that you cannot discuss several differ-
ent ideas in a single paragraph, but it does mean that
these ideas ought to be related and help make clear
the overall point of the paragraph:

1. If you begin a paragraph by discussing a par-
ticular point or issue, don't veer off into a dis-
cussion of something else-stick to the point
with which you started.

2. When you have made your overall point and
are ready to move on to your next point, start a
new paragraph.

Technical Stuff

Often students believe that philosophy is difficult
because some philosophers use big words and write
long, complicated sentences that no one can under-
stand. This might indeed be a problem that other
writers have, but you should avoid making it your
problem. Here are a few things to avoid:

Do not use big words unless you absolutely
understand them.

0 Do not use big words where smaller words
would do. 0 Do not use lots of words when fewer will do.

0 Do not use fancy terminology simply because
you think you are supposed to.

Do not use technical terms without explaining
what they mean in nontechnical vocabulary.

Do not use flowery prose that obscures the
point you are trying to make.

Do not make up words.

To get the most out of writing a philosophy paper
(and this typically means to force yourself to put the
most into it), you should assume that your reader
(your professor or teaching assistant) has only mini-
mal background in the topic you are discussing; that
is, you should write for “intelligent laypersons,”
like (for example) your parents or best friends. This
means, for instance, that if you are dealing with an
example, you should lay out the example and explain
how it is relevant to your paper. If you are discuss-
ing a principle or a distinction, you should state
where you got the principle or distinction and how
it is relevant. Do not assume that your professor or
teaching assistant knows or understands any of this,
because if you don’t explain it to us, we can't tell if
you understand it.

Of course, you should distinguish between rele-
vant and irrelevant points. Irrelevant background
information prevents you from getting to the point
of your paper.

Your paper should begin with an introduc-
tion that is clear and brief It should explain what
the topic, problem, or question is that you will be
dealing with, and it should explain (briefly) how
you plan to go about discussing the topic, solving
the problem, or answering the question. In short,
it should be like a mini-outline, and it should tell
your instructor what you are going to do in your
paper and why he or she should care (that is, what is
important or interesting about the problem). Your
paper should end with a conclusion that is appro-
priately symmetric to the introduction, briefly sum-
marizing how you have achieved the goals laid out
in the introduction.

Remember to use your spell-check. Spelling er-
rors at the college level are embarrassing, unaccept-
able, and unnecessary.Absolutely, positively have someone else proof-

read your paper! This could be a friend, a room-
mate, or a classmate.

Plagiarism

Plagiarism is against university policy and should
be absolutely avoided. When you copy someone
else's words directly (that is, word-for-word) with-
out putting them in quotes and properly attribut-
ing them to the person who wrote them, the words

appear in your paper as if they were your own. This

is akin to theft, and you should be careful not to
do this.

Use Quotation Mar/(5

Do not copy sentences or phrases directly from your
texts or class handouts (or any other materials), un-

less you enclose the copied sentence or phrase in quo-
tation marks and provide an accompanying citation.

Standardize Your Citations

last name and the page number of the quote: (Kant,
p. x). If you are citing an article that appears in a
book written by someone other than the author of
the article, your citation should appear as follows:
(Nagel in Perry, Bratman, and Fischer, p. x). One
way to avoid having to write out a long citation like
this over and over is to add a footnote after the first
such citation that notes that Nagel’s article appears
in Perry, Bratman, and Fischer. Thereafter, your
citation can appear this way: (Nagel, p. x).

Paraphrase Carefidly

If you provide an adequate paraphrase or summary
of someone else's words, you need not put your

paraphrase in quotation marks-it is sufficient to provide just a citation. However, changing a word
or two of someone else’s words does not amount to

an adequate paraphrase. An adequate paraphrase
consists of your words. Anything quoted directly
from someone else must be in quotes as well as cited.

Avoid Plagiarizing from the Internet

The Internet provides many temptations to plagia-
rize material. Absolutely and positively avoid pla-
giarism from an Internet source, no matter how
enticing. Keep in mind that your instructors have
various Internet resources available to combat
plagiarism-both from Internet sources and also
from fellow students and other materials. For exam-
ple, your instructor can type in sentences from your
paper and-believe it or not-find out whether you
have taken the material from another source or even
another student’s paper. Be aware that there are var-

ious new resources available to your instructors and
that she or he may well employ them!

Other Resources

Other material will be available on the student
website associated with the textbook. The follow-
ing two books are helpful: Hugo Bedau, Thin/(-
ing and Writing About Philosophy, Second Edition
(Boston: Bedford/St. Martin’s, 2002) and Zachary
Seech, Writing Philosophy Papers (Belmont, CA:
Wadsworth, 1993). There is a helpful discussion of
arguments, with special emphasis on arguments in
ethics, in David Boonin and Graham Oddie, eds.,
What's Wrong? Applied Ethieists and Their Critics

(New York: Oxford University Press, 2005), esp.
pp. 2-24.

We are very grateful to Alison Shalinsky
for permission to revise and edit her handout,
“Writing Philosophy Papers,” Department of Phi-
losophy, University of California, Riverside. The

material presented in this section is due largely to
Shalinsky.

The Nature of Mind

DAVID M. ARMSTRONG
David M. Armstrong (1926-2014) was Emeritus Professor of Philosophy at the University. of
Sydney. He is well known for his work in metaphysics and philosophy of mind, and his
publications include Perception and the Physical World, A Materialist Theory oft/1c Mind, and
Universal; and Scientific Realism. MEN have minds, that is to say. they per-
ceive, they have sensations, emotions, be-
liefs, thoughts, purposes. and desires.I

What is it to have a mind.> What is it to perceive. to feel emotion, to hold a belief, or to have a purpose?
In common with many other modern philosophers,
I think that the best clue we have to the nature of
mind is furnished by the discoveries and hypotheses
of modern science concerning the nature of man.
What does modern science have to say about the
nature of man? There are, of course, all sorts of
disagreements and divergencies in the views of indi-
vidual scientists. But I think it is true to say that one view is steadily gaining ground, so that it bids fair to
become established scientific doctrine. This is the
view that we can give a complete account of man in
purely physico-chemical terms. This view has received
a tremendous impetus in the last decade from the
new subject of molecular biology, a subject which
promises to unravel the physical and chemical mech-
anisms which lie at the basis of life. Before that time,
it received great encouragement from pioneering
work in neurophysiology pointing to the likelihood
of a purely electro-chemical account of the working
of the brain. I think it is fair to say that those scien-
tists who still reject the physico-chemical account of
man do so primarily for philosophical, or moral, or
religious reasons, and only secondarily, and half-
heartedly, for reasons of scientific detail. This is not
to say that in the future new evidence and new prob-
lems may not come to light which will force science
to reconsider the physico-chemical view of man. But
at present the drift of scientific thought is clearly set
towards the physico-chemical hypothesis. And we
have nothing better to go on than the present.

For me, then, and for many philosophers who
think like me, the moral is clear. We must try to
work out an account of the nature of mind which is
compatible with the view that man is nothing but a
physico-chemical mechanism.

And . . . I shall be concerned to do just this: to

sketch (in barest outline) what may be called a Ma-
terialist or Physicalist account of the mind.
But before doing this I should like to go back and
consider a criticism of my position which must in-
evitably occur to some. What reason have I, it may
be asked, for taking my stand on science? Even
granting that 1 am right about what is the currently
dominant scientific view of man, why should we
concede science a special authority to decide ques-
tions about the nature of man? What of the author-
ity of philosophy, of religion, of morality, or even of
literature and art? Why do I set the authority of sci-
ence above all these? Why this “scientism”?

It seems to me that the answer to this question is very
simple. If we consider the search for truth, in all its
fields, we find that it is only in science that men versed
in their subject can, after investigation that is more or
less prolonged, and which may in some cases extend beyond a single human lifetime, reach substantial
agreement about what is the case. It is only as a result
of scientific investigation that we ever seem to reach an
intellectual consensus about controversial matters.

In the Epistle Dedicatory to his De Corpore
Hobbes wrote of William Harvey, the discoverer of
the circulation of the blood, that he was “the only
man I know, that conquering envy, hath established
a new doctrine in his life-time."

Before Copernicus, Galileo and Harvey, Hobbes
remarks, “there was nothing certain in natural phi-
losophy.” And, we might add, with the exception of
mathematics, there was nothing certain in any other
learned discipline.

These remarks of Hobbes are incredibly reveal-
ing. They show us what a watershed in the intellec-
tual history of the human race the seventeenth
century was. Before that time inquiry proceeded, as
it were, in the dark. Men could not hope to see their
doctrine established, that is to say, accepted by the
vast majority of those properly versed in the subject
under discussion. There was no intellectual consen-
sus. Since that time, it has become a commonplace
to see new doctrines, sometimes of the most far-

reaching kind, established to the satisfaction of the
learned, often within the lifetime of their first pro-
ponents. Science has provided us with a method of
deciding disputed questions. This is not to say, of
course, that the consensus of those who are learned
and competent in a subject cannot be mistaken. Of
course such a consensus can be mistaken. Sometimes
it has been mistaken. But, granting fallibility, what
better authority have we than such a consensus?

Now this is of the utmost importance. For in phi-
losophy, in religion, in such disciplines as literary
criticism, in moral questions in so far as they are
thought to be matters of truth and falsity, there has
been a notable failure to achieve an intellectual con-
sensus about disputed questions among the learned.
Must we not then attach a peculiar authority to the
discipline that can achieve a consensus? And if it
presents us with a certain vision of the nature of man,
is this not a powerful reason for accepting that vision?

I will not take up here the deeper question why it
is that the methods of science have enabled us to
achieve an intellectual consensus about so many dis-
puted matters. That question, I think, could receive no brief or uncontroversial answer. I am resting my
argument on the simple and uncontroversial fact
that, as a result of scientific investigation, such a con-
sensus has been achieved.

It may be replied-it often is replied-that while
science is all very well in its own sphere-the sphere
of the physical, perhaps-there are matters of fact on
which it is not competent to pronounce. And among
such matters, it may be claimed, is the question what
is the whole nature of man. But I cannot see that this
reply has much force. Science has provided us with
an island of truths, or, perhaps one should say, a raft
of truths, to bear us up on the sea of our disputatious
ignorance. There may have to be revisions and re-
finements, new results may set old findings in a new
perspective, but what science has given us will not be
altogether superseded. Must we not therefore appeal
to these relative certainties for guidance when we
come to consider uncertainties elsewhere? Perhaps
science cannot help us to decide whether or not there
is a God, whether or not human beings have immor-
tal souls, or whether or not the will is free. But if sci-
ence cannot assist us, what can? I conclude that it is
the scientific vision ofman, and not the philosophical
or religious or artistic or moral vision of man, that is
the best clue we have to the nature of man. And it is
rational to argue from the best evidence we have.
Having in this way attempted to justify my procedure,
I turn back to my subject: the attempt to work out an
account of mind, or, if you prefer, of mental process,
within the framework of the physico-chemical or, as
we may call it, the Materialist view of man.

Now there is one account of mental process that is
at once attractive to any philosopher sympathetic to a
Materialist view of man: this is Behaviourism. For-
mulated originally by a psychologist, ]. B. Watson, it
attracted widespread interest and considerable sup-
port from scientifically oriented philosophers. Tradi-
tional philosophy had tended to think of the mind as
a rather mysterious inward arena that lay behind,
and was responsible for, the outward or physical
behaviour of our bodies. Descartes thought of this
inner arena as a sgiritualsubstanmd it was this con-
ce tion of the mind as s iritual ob'ect that Gilbert
iourism, in his important book The Concept of Mind.He ridiculed the Cartesian view as the dogma of “the
ghost in the machine." The mind was not something
behind the behaviour of the body, it was simply part
of that physical behaviour. My anger with you is not
some modification of a spiritual substance which
somehow brings about aggressive behaviour; rather it
is the aggressive behaviour itself; my addressing
strong words to you, striking you, turning my back
on you, and so on. Thought is not an inner process
that lies behind, and brings about, the words I speak
and write: it is my speaking and writing. The mind is
not an inner arena, it is outward act.

It is clear that such a view of mind fits in very well
with a completely Materialistic or Physicalist view
of man. If there is no need to draw a distinction
between mental processes and their expression in
physical behaviour, but if instead the mental pro-
cesses are identified with their so-called “expres-
sions," then the existence of mind stands in no
conflict with the view that man is nothing but a
physico-chemical mechanism.

However, the version of Behaviourism that
I have just sketched is a very crude version, and its
crudity lays it open to obvious objections. One obvi-
ous difficulty is that it is our common experience
that there can be mental processes going on although
there is no behaviour occurring that could possibly
be treated as expressions of these processes. A man
may be angry, but give no bodily sign; he may think,
but say or do nothing at all.

In my view, the most plausible attempt to refine
Behaviourism with a view to meeting this objection
was made by introducing the notion of a disposition
to behave. (Dispositions to behave play a particularly
important part in Ryle’s account of the mind.) Let
us consider the general notion of disposition first.
Brittleness is a disposition, a disposition possessed
by materials like glass. Brittle materials are those
which, when subjected to relatively small forces,
break or shatter easily. But breaking and shattering
easily is not brittleness, rather it is the manifestation
of brittleness. Brittleness itself is the tendency or li-
ability of the material to break or shatter easily. A
piece of glass may never shatter or break through-
out its whole history, but it is still the case that it is
brittle: it is liable to shatter or break if dropped quite
a small way or hit quite lightly. Now a disposition to behave is simply a tendency or liability of a person to
behave in a certain way under certain circumstances.
The brittleness of glass is a disposition that the glass
retains throughout its history, but clearly there could
also be dispositions that come and go. The disposi-
tions to behave that are of interest to the Behaviour-
ist are, for the most part, of this temporary character.
Now how did Ryle and others use the notion of a
disposition to behave to meet the obvious objection
to Behaviourism that there can be mental processes
going on although the subject is engaging in no rel-
evant behaviour? Their strategy was to argue that in
such cases, although the subject was not behaving
in any relevant way, he or she was disposed to behave
in some relevant way. The glass does not shatter, but
it is still brittle. The man does not behave, but he
does have a disposition to behave. We can say he
thinks although he does not speak or act because at
that time he was disposed to speak or act in a certain
way. If he had been asked, perhaps, he would have
spoken or acted. We can say he is angry although he
does not behave angrily, because he is disposed so to
behave. If only one more word had been addressed to
him, he would have burst out. And so on. In this way
it was hoped that Behaviourism could be squared
with the obvious facts.
It is very important to see just how these thinkers
conceived of disposition. I quote from Ryle
To possess a dispositional property is not to be in a par-
ticular state, or to undergo a particular change; it is to be
bound or liable to be in a particular state, or to un-
dergo a particular change, when a particular condition
is realised. (The Concept of Mind, p. 43, my italics.)
So to explain the breaking of a lightly struck glass
on a particular occasion by saying it was brittle is, on
this view of dispositions, simply to say that the glass
broke because it is the sort of thing that regularly
breaks when quite lightly struck. The breaking was
the normal behaviour, or not abnormal behaviour,
of such a thing. The brittleness is not to be conceived
of as a cause for the breakage, or even, more vaguely,
afaetor in bringing about the breaking. Brittleness is
just the fact that things of that sort break easily.
But although in this way the Behaviourists did
something to deal with the objection that mental
processes can occur in the absence of behaviour, itseems clear, now that the shouting and the dust
have died, that they did not do enough. When 1
think, but my thoughts do not issue in any action, it
seems as obvious as anything is obvious that there is
something actually going on in me which consti-
tutes my thought. It is not simply that I would speak
or act ifsome conditions that are unfulfilled were to
be fulfilled. Something is currently going on, in the
strongest and most literal sense of “going on," and
this something is my thought. Rylean Behaviourism
denies this, and so it is unsatisfactory as a theory of
mind. Yet I know of no version of Behaviourism
that is more satisfactory. The moral of those of us
who wish to take a purely physicalistic view of man
is that we must look for some other account of the
nature of mind and of mental processes.

But perhaps we need not grieve too deeply about
the failure of Behaviourism to produce a satisfac-
tory theory of mind. Behaviourism is a profoundly
unnatural account of mental processes. If some-
body speaks and acts in certain ways it is natural to
speak of this speech and action as the expression of
his thought. It is not at all natural to speak of his
speech and action as identical with his thought. We
naturally think of the thought as something quite
distinct from the speech and action which, under
suitable circumstances, brings the speech and action
about. Thoughts are not to be identified with behav-
iour, we think, they lie behind behaviour. A man's
behaviour constitutes the reason we have for attrib-
uting certain mental processes to him, but the behav-
iour cannot be identified with the mental processes.

This suggests a very interesting line of thought
about the mind. Behaviourism is certainly wrong. but
perhaps it is not altogether wrong. Perhaps the Behav-
iorists are wrong in identifying the mind and mental
occurrences with behaviour, but perhaps they are
right in thinking that our notion ofa mind and of in-
dividual mental states is logically tied to behaviour. For
perhaps what we mean by a mental state is some state
of the person which, under suitable circumstances
brings about a certain range of behaviour. Perhaps
mind can be defined not as behaviour, but rather as
the inner cause of certain behaviour. Thought is not
speech under suitable circumstances, rather it is some-
thing within the person which, in suitable circum-
stances brings about speech. And, in fact, I believe that this is the true account, or, at any rate, a true first ac-
count, of what we mean by a mental state.

How does this line of thought link up with a
purely physicalist view of man? The position is,
I think, that while it does not make such a physical-
ist view inevitable, it does make it possible. It does
not entail, but it is compatible with, a purely physi-
calist view ofman. For ifour notion ofthe mind and
mental states is nothing but that of a cause within
the person of certain ranges of behaviour, then it be-
comes a scientific question, and not a question oflog-
ical analysis, what in fact the intrinsic nature of that
cause is. The cause might be,“ Descartes thought
it was, a spiritual substance working through the
pineal gland to produce the "591.13wain behav-
iour of whigh men are capable. It might be breath,
or specially smooth 311375553? atoms dispersed
throughout the body; it might be many other things.
But in fact the verdict of modern science seems to be
that the sole cause of mind-betokening behaviour in
man and the higher animals is the physico-chemical
workings of the central nervous system. And so, as-
suming we have correctly'characterised our concept
of a mental state as nothing but the cause of certain
sorts of behaviour, then we can identify these men-
tal states with purely physical states of the central
nervous system.

At this point we may stop and go back to the Be-
haviourists’ dispositions. We saw that, according to
them, the brittleness of glass or, to take another ex-
ample, the elasticity of rubber, is not a state of the
glass or the rubber, but is simply the fact that things
of that sort behave in the way they do. But now let
us consider how a scientist would think about brit-
tleness or elasticity. Faced with the phenomenon of
breakage under relatively small impacts, or the phe-
nomenon of stretching when a force is applied fol-
lowed by contraction when the force is removed, he
will assume that there is some current state of the
glass or the rubber which is responsible for the char-
acteristic behaviour of samples of these two materi-
als. At the beginning he will not know what this
state is, but he will endeavor to find out, and he may
succeed in finding out. And when he has found out
he will very likely make remarks of this sort: “We
have discovered that the brittleness ofglass is in fact
a certain sort of pattern in the molecules of the glass.” That is to say, he will identify brittleness with
the state of the glass that is responsible for the liabil-
ity of the glass to break. For him, a disposition of an
object is a state of the object. What makes the state a
state of brittleness is the fact that it gives rise to the
characteristic manifestations of brittleness. But the
disposition itselfis distinct from its manifestation: it
is the state of the glass that gives rise to these mani-
festations in suitable circumstances.

You will see that this way of looking at disposi-
tions is very different from that of Ryle and the Be-
haviourists. The great difference is this: If we treat
dispositions as actual states, as I have suggested that
scientists do, even if states whose intrinsic nature may
yet have to be discovered, then we can say that dispo-
sitions are actual causes, or causal factors, which, in
suitable circumstances, actually bring about those
happenings which are the manifestations of the dis-
position. A certain molecular constitution of glass
which constitutes its brittleness is actually responsible
for the fact that, when the glass is struck, it breaks.

Now I shall not argue the matter here, because
the detail of the argument is technical and difficult,2
but I believe that the view of dispositions as states,
which is the view that is natural to science, is the cor-
rect one. I believe it can be shown quite strictly that,
to the extent that we admit the notion of dispositions
at all, we are committed to the view that they are
actual states of the object that has the disposition. I
may add that I think that the same holds for the
closely connected notions of capacities and powers.
Here I will simply assume this step in my argument.

But perhaps it can be seen that the rejection ofthe
idea that mind is simply a certain range of man’s be-
haviour in favour of the view that mind is rather the
inner cause of that range of man’s behaviour is
bound up with the rejection of the Rylean view of
dispositions in favour of one that treats dispositions
as states of objects and so as having actual causal
power. The Behaviourists were wrong to identify
the mind with behaviour. They were not so far off
the mark when they tried to deal with cases where
mental happenings occur in the absence of behav-
iour by saying that these are dispositions to behave.
But in order to reach a correct view, I am suggesting,
they would have to conceive of these dispositions as
actual states of the person who has the disposition,states that have actual power to bring about behav-
iour in suitable circumstances. But to do this is to
abandon the central inspiration of Behaviourism:
that in talking about the mind we do not have to go
behind outward behaviour to inner states.

And so two separate but interlocking lines of
thought have pushed me in the same direction. The
first line of thought is that it goes profoundly against
the grain to think ofthe mind as behaviour. The mind
is, rather, that which stands behind and brings about
our complex behaviour. The second line of thought
is that the Behaviourists' dispositions, properly con-
ceived, are really states that underlie behaviour, and,
under suitable circumstances, bring about behaviour.
Putting these two together, we reach the conception of
a mental state as a state of the person apt for producing
certain ranges of behaviour. This formula: a mental
state is a state of the person apt for producing certain
ranges of behaviour, I believe to be a very illuminating
way of looking at the concept of a mental state. I have
found it very fruitful in the search for detailed logical
analyses of the individual mental concepts.

Now, I do not think that Hegel's dialectic has
much to tell us about the nature of reality. But I think
that human thought often moves in a dialectical way,
from thesis to antithesis and then to the synthesis.
Perhaps thought about the mind is a case in point.
I have already said that classical philosophy tended to
think of the mind as an inner arena of some sort.
This we may call the Thesis. Behaviourism moved to
the opposite extreme: the mind was seen as outward
behaviour. This is the Antithesis. My proposed Syn-
thesis is that the mind is properly conceived as an
inner principle, but a principle that is identified in
terms ofthe outward behaviour it is apt for bringing
about. This way of looking at the mind and mental
states does not itselfentail a Materialist or Physicalist
view ofman, for nothing is said in this analysis about
the intrinsic nature of these mental states. But if we
have. as l have asserted that we do have, general sci-
entific grounds for thinking that man is nothing but
a physical mechanism, we can go on to argue that
the mental states are in fact nothing but physical
states ofthe central nervous system.

Along these lines, then, I would look for an account of
the mind that is compatible with a purely Materialist theory of man. I have tried to carry out this pro-
gramme in detail in A Materiel/is! Theory of the Mind.
There are, as may be imagined. all sorts of powerful
objections that can be made to this view. But [in what
follows] . . . I propose to do only one thing. I will de-
velop one very important objection to my view of the
mind-an objection felt by many philosophers-and
then try to show how the objection should be met.
The view that our notion of mind is nothing but
that of an inner principle apt for bringing about
certain sorts ofbehaviour may he thought to share a
certain weakness with Behaviourism. Modern phi-
losophers have put the point about Behaviourism
by saying that although Behaviourism may be a sat-
isfactory account of the mind from an other-person
point of view. it will not do as afirst-person account.
To explain. In our encounters with other people. all
we ever observe is their behaviour: their actions.
their speech. and so on. And so, if we simply con-
sider other people, Behaviourism might seem to do
full justice to the facts. But the trouble about Be-
haviourism is that it seems so unsatisfactory as ap-
plied to our own case. In our own case, we seem to
be aware of so much more than mere behaviour.
Suppose that now we conceive of the mind as an
inner principle apt for bringing about certain sorts of
behaviour. This again fits the other-person cases very
well. Bodily behaviour of a very sophisticated sort is
observed, quite different from the behaviour that ordi-
nary physical objects display. I t is inferred that this be-
haviour must spring from a very special sort of inner
cause in the object that exhibits this behaviour. This
inner cause is christened “the mind.” and those who
take a physicalist view of man argue that it is simply
the central nervous system ofthe body observed. Com-
pare this with the case of glass. Certain characteristic
behaviour is observed: the breaking and shattering of
the material when acted upon by relatively small
forces. A special inner state of the glass is postulated to
explain this behaviour. Those who take a purely physi-
calist view of glass then argue that this state is a natural
state of the glass. It is. perhaps. an arrangement of its
molecules. and not, say, the peculiarly malevolent dis-
position of the demons that dwell in glass.
But when we turn to our own case. the position
may seem less plausible. We are conscious. we have
experiences. Now can we say that to be conscious. to have experiences, is simply for something to go on
within us apt for the causing of certain sorts of be-
haviour? Such an account does not seem to do any
justice to the phenomena. And so it seems that our
account of the mind, like Behaviourism, will fail to
do justice to the first-person case.

ln order to understand the objection better it
may be helpful to consider a particular case. If you
have driven for a very long distance without a break,
you may have had experience of a curious state of
automatism, which can occur in these conditions.
One can suddenly “come to“ and realise that one has
driven for long distances without being aware of
what one was doing, or, indeed, without being
aware ofanything. One has kept the car on the road,
used the brake and the clutch perhaps, yet all with-
out any awareness of what one was doing.

Now, if we consider this case it is obvious that in
some sense mental processes are still going on when
one is in such an automatic state. Unless one’s will
was still operating in some way, and unless one was
W Yet, of course, something mental is
lacking. Now, I think, when it is alleged that an
account of mind as an inner principle apt for the
production of certain sorts of behaviour leaves out
consciousness or experience, what is alleged to have
been left out is just whatever is missing in the auto-
matic driving case. It is conceded that an account of
mental processes as states of the person apt for the
production of certain sorts of behaviour may very
possibly be adequate to deal with such cases as that
of automatic driving. It may be adequate to deal
with most of the mental processes of animals, who
perhaps spend a good deal of their lives in this state
of automatism. But, it is contended, it cannot deal
with the consciousness that we normally enjoy.

1 will now try to sketch an answer to this impor-
tant and powerful objection. Let us begin in an ap-
parently unlikely place, and consider the way that
an account of mental processes of the sort 1 am
giVing would deal with sense-perception.

Now psychologists, in particular, have long re-
alised that there is a very close logical tie between
sense-perception and selective behaviour. Suppose we
want to decide whether an animal can perceive the

difference between red and green. We might give the animal a choice between two pathways, over one of
which a red light shines and over the other of which
a green light shines. If the animal happens by chance
to choose the green pathway we reward it; if it hap-
pens to choose the other pathway we do not reward
it. If, after some trials, the animal systematically takes
the green-lighted pathway, and if we become assured
that the only relevant differences in the two path-
ways are the differences in the colour ofthe lights, we
are entitled to say that the animal can see this colour
difference. Using its eyes, it selects between red-
lighted and green-lighted pathways. So we say it can
see the difference between red and green.

Now a Behaviourist would be tempted to say that
the animal’s regularly selecting the green-lighted path-
way was its perception of the colour difference. But this
is unsatisfactory, mcause-we Mo say that per-
ception is something that goes on within the person or
animal-within its mind-although2 of course, this
mental event is normally caused by the op_eration of the
environment u n the or anism. Suppose, however,
mm for selective behav-
iour towards the current environment, and suppose we
think of these capacities, like dispositions, as actual
inner states of the organism. We can then think ofthe
animal's perception as a state within the animal apt, if
the animal is so impelled, for selective behaviour be-
tween the red- and green-lighted pathways.
states or events a t for the roduction of certain
sorts of selective behaviour toward; our engagin-
2152!- To perceive is like acquiring a key to a door.
You do not have to use the key: you can put it in
your pocket and never bother about the door. But if
you do want to open-the door the key may be essen-
tial. The blind man is a man who does not acquire
certain keys, and, as a result, is not able to operate in
his environment in the way that somebody who has
his sight can operate. It see 5 then, a very promis-
ing view to take of erce tions th
states ne he sorts of selectiv
they enable the perceiver to exhibitI if so impelled.

ow how 15 IS iscussmn ofperception related
to the question of consciousness ofexperience, the sort
of thing that the driver who is in a state ofautoma-
tism has not got, but which we normally do have?
Simply this. My proposal is that consciousness, in this sense of the word, is nothing but perception or
awareness of the state of our own mind. The driver in
a state of automatism perceives, or is aware of, the
road. If he did not, the car would be in a ditch. But
he is not currently aware of this awareness of the
road. He perceives the road, but he does not per-
ceive his perceiving, or anything else that is going on
in his mind. He is not, as we normally are, conscious
of what is going on in his mind.

And so I conceive of consciousness or experience,
in this sense of the words, in the way that Locke and
Kant conceived it, as like perception. Kant, in a strik-
ing phrase, spoke of “inner sense.” We cannot directly
observe the minds of others, but each of us has the
power to observe directly our own minds, and “per-
ceive” what is going on there. The driver in the auto-
matic state is one whose “inner eye” is shut: who is not
currently aware of what is going on in his own mind.

Now if this account is along the right lines, why
should we not give an account of this inner observa-
tion along the same lines as we have already given of
perception? Why should we not conceive of it as an
inner state, a state in this case directed towards other
inner states and not to the environment, which en-
ables us, if we are so impelled, to behave in a selec-
tive way towards our own states of mind ? One who is
aware, or conscious, of his thoughts or his emotions
is one who has the capacity to make discriminations
between his different mental states. His capacity
might be exhibited in words. He might say that he
was in an angry state of mind when, and only when,
he was in an angry state of mind. But such verbal
behaviour would be the mere expression or result of
the awareness. The awareness itself would be an
inner state: the sort of inner state that gave the man
a capacity for such behavioural expressions.

So I have argued that consgigusngss of our own
WW
may_then be W

sglsstimhchawvauwm
All this is meant to be simply a logical analysis ofcon-
sciousness, and none of it entails, although it does not
rule out, a purely physicalist account of what these
inner states are. But if we are convinced, on general
scientific grounds, that a purely physical account of man is likely to be the true one, then there seems to be
no bar to our identifying these inner states with
purely physical states of the central nervous system.
And so consciousness of our own mental state be-
comes simply the scanning of one part of our central
nervous system by another. Consciousness is a self-
scanning mechanism in the central nervous system.
As 1 have emphasised before, I have done no more
than sketch a programme for a philosophy of mind.
There are all sorts of expansions and elucidations to
be made, and all sorts of doubts and difficulties to be
stated and overcome. But I hope I have done enough
to show that a purely physicalist theory of the mind
is an exciting and plausible intellectual option.
NOTES

1. Inaugural lecture of the Challis Professor of
Philosophy at the University of Sydney (1965):
slightly amended (1968).

2. It is presented in my book A Materialist Theory of
the Mind (1968) ch. 6, sec. VI.

KEY TERMS
Materialist
Physicalist
Behaviorism
STUDY QUESTIONS

1. Is there anything about desires, beliefs, or emotions
that requires an account that is more robust than a
purely physicochemical one? Why do you think
people have thought so in the past?

2. Armstrong claims that “it is only as a result of sci-
entific investigation that we ever seem to reach an

intellectual consensus about controversial matters."
Do you think he is right about this?

i 3. According to Armstrong, what is one obvious dif-
ficulty with behaviorism?

4. Armstrong thinks that mind is “the inner cause of
certain behaviour." How does he argue that this
idea can be squared with a “physicalist view" of
human beings?

5. How does the first-person point of view supposedly
cause problems for Armstrong’s theory? How does
Armstrong reply to these worries? What Mary Didn’t Know
FRANK JACKSON
Frank Jackson (l943- ) is a Distinguished Professor of Philosophy at the Australian National
University. He has made important contributions in philosophy of mind, metaphysics, philo-
sophical methodology, and ethics. He is the author of From Metaphysics to Ethics: A Defence
of Conceptual Analysis. P 1 ARY is confined to a black-and-white
room, is educated through black-and-
white books and through lectures relayed

on black-and-white television. In this way she learns
everything there is to know about the physical
nature of the world. She knows all the physical
facts about us and our environment, in a wide sense
of‘physical’ which includes everything in completed
physics, chemistry, and neurophysiology, and all
there is to know about the causal and relational factors consequent upon all this, including of course
functional roles. If physicalism is true, she knows all
there is to know. For to suppose otherwise is to sup-
pose that there is more to know than every physical
fact, and that is just what physicalism denies.

Physicalism is not the noncontroversial thesis that
the actual world is largely physical, but the chal-
lenging thesis that it is entirely physical. This is why
physicalists must hold that complete physical knowl-
edge is complete knowledge simpliciter. For SUppose
it is not complete: then our world must differ from
a world, W(P), for which it is complete, and the dif-
ference must be in nonphysical facts; for our world
and W(P) agree in all matters physical. Hence, physi-
calism would be false at our world [though contin-
gently so, for it would be true at W(P)l.l It seems, however, that Mary does not know all
there is to know. For when she is let out of the black-
and-white room or given a color television, she will
learn what it is like to see something red, say. This is
rightly described as learning-she will not say “ho,
hum." Hence, physicalism is false. This is the
knowledge argument against physicalism in one of
its manifestations.2 This note is a reply to three ob-
jections to it mounted by Paul M. Churchland.’

1. Three Clarifications

The knowledge argument does not rest on the dubi-
ous claim that logically you cannot imagine what
sensing red is like unless you have sensed red.
Powers of imagination are not to the point. The con-
tention about Mary is not that, despite her fantastic
grasp of neurophysiology and everything else physi-
cal, she could not imagine what it is like to sense red;
it is that, as a matter of fact, she would not know. But
if physicalism is true, she would know; and no great
powers of imagination would be called for. lmagi-
nation is a faculty that those who lack knowledge
need to fall back on.

Secondly, the intensionality of knowledge is not
to the point. The argument does not rest on assum-
ing falsely that, ifS knows that a is F and ifa = b,
then S knows that b is F. It is concerned with the
nature of Mary's total body ofknowledge before she
is released: is it complete, or do some facts escape it?
What is to the point is that S may know that a is F
and know thata = b, yet arguably not know thatb is
F, by virtue of not being sufficiently logically alert to
follow the consequences through. If Mary's lack of
knowledge were at all like this, there would be no
threat to physicalism in it. But it is very hard to be-
lieve that her lack ofknowledge could be remedied
merely by her explicitly following through enough
logical consequences of her vast physical knowl-

edge. Endowing her with great logical acumen and
persistence is not in itselfenough to fill in the gaps in
her knowledge. On being let out, she will not say “I could have worked all this out before by making
some more purely logical inferences."

Thirdly, the knowledge Mary lacked which is
of particular point for the knowledge argument
against physicalism is knowledge about tlw experi-
ences of others, not about her own. When she is let
out, she has new experiences, color experiences she
has never had before. It is not, therefore, an objec-
tion to physicalism that she learns sometlzing on
being let out. Before she was let out, she could not
have known facts about her experience of red, for
there were no such facts to know. That physicalist
and nonphysicalist alike can agree on. After she is
let out, things change; and physicalism can happily
admit that she learns this; after all, some physical
things will change, for instance, her brain states and
their functional roles. The trouble for physicalism is
that, after Mary sees her first ripe tomato, she will
realize how impoverished her conception of the
mental life of other; has been all along. She will real-
ize that there was, all the time she was carrying out
her laborious investigations into the neurophysiolo-
gies of others and into the functional roles of their
internal states, something about these people she
was quite unaware of. All along their experiences
(or many of them, those got from tomatoes, the
sky, . . .) had a feature conspicuous to them but until
now hidden from her (in fact, not in logic). But she
knew all the physical facts about them all along:
hence, what she did not know until her release is not
a physical fact about their experiences. But it is a fact
about them. That is the trouble for physicalism.

II. Churchland’s Three Objections

(i) Churchland's first objection is that the knowl-
edge argument contains a defect that “is simplicity
itself" (23). The argument equivocates on the sense
of ‘knows about’. How so? (Thurchland suggests
that the following is “a conveniently tightened ver-
sion” ofthe knowledge argument:

I. Mary knows everything there is to know

about brain states and their properties.

2. It is not the case that Mary knows everything

there is to know about sensations and their
properties. Therefore, by Leibniz’s law,
3. Sensations and their properties 515 brain states
and their properties (23).
Churchland observes, plausibly enough, that the
type or kind of knowledge involved in premise l is
distinct from the kind of knowledge involved in
premise 2. We might follow his lead and tag the first
‘knowledge by description’, and the second ‘knowl-
edge by acquaintance'; but, whatever the tags, he is
right that the displayed argument involves a highly
dubious use of Leibniz’s law.

My reply is that the displayed argument may be
convenient, but it is not accurate. It is not the knowl-
edge argument. Take, for instance, premise l. The
whole thrust of the knowledge argument is that
Mary (before her release) does not know everything
there is to know about brain states and their proper-
ties, because she does not know about certain qualia
associated with them. What is complete, according
to the argument, is her knowledge of matters physi-
cal. A convenient and accurate way ofdisplaying the
argument is:

l.' Mary (before her release) knows everything

physical there is to know about other people.

2.’ Mary (before her release) does not know ev-

erything there is to know about other people
(because she learns something about them on
her release).

Therefore,

3.’ There are truths about other people (and her-

self) which escape the physiealist story.

What is immediately to the point is not the kind,
manner, or type of knowledge Mary has, but w/iat
she knows. What she knows beforehand is ex hypo-
thesi everything physical there is to know, but is it
everything there is to know? That is the crucial
question.

There is, though, a relevant challenge involving
questions about kinds of knowledge. It concerns the
support for premise 2'. The case for premise 2' is that
Mary learns something on her release, she acquires
knowledge, and that entails that her knowledge beforehand (what she knew, never mind whether by
description, acquaintance, or whatever) was incom-
plete. The challenge, mounted by David Lewis and
Laurence Nemirow, is that on her release Mary does
not learn something or acquire knowledge in the rel-
evant sense. What Mary acquires when she is re-
leased is a certain representational or imaginative
ability; it is knowledge how rather than knowledge
that. Hence, a physicalist can admit that Mary ac-
quires something very significant of a knowledge
kind-which can hardly be denied-without ad-
mitting that this shows that her earlier factual
knowledge is defective. She knew all that there was
to know about the experiences of others beforehand,
but lacked an ability until after her release.;

Now it is certainly true that Mary will acquire
abilities of various kinds after her release. She will,
for instance, be able to imagine what seeing red is
like, be able to remember what it is like, and be able
to understand why her friends regarded her as so
deprived (something which, until her release, had
always mystified her). But is it plausible that that is
all she will acquire? Suppose she received a lecture
on skepticism about other minds while she was in-
carcerated. On her release she sees a ripe tomato in
normal conditions, and so has a sensation of red. Her
first reaction is to say that she now knows more about
the kind ofexperiences others have when looking at
ripe tomatoes. She then remembers the lecture and
starts to worry. Does she really know more about
what their experiences are like, or is she indulg-
ing in a wild generalization from one case? In the
end she decides she does know, and that skepticism
is mistaken (even if, like so many of us, she is not
sure how to demonstrate its errors). What was she
to-ing and fro-ing about-her abilities? Surely not;
her representational abilities were a known constant
throughout. What else then was she agonizing about
than whether or not she had gained factual knowl-
edge of others? There would be nothing to agonize
about if ability was all she acquired on her release.

I grant that l have no proof that Mary acquires on
her release, as well as abilities, factual knowledge
about the experiences ofothers-and not just because
I have no disproofof skepticism. My claim is that the
knowledge argument is a valid argument from
highly plausible, though admittedly not demonstrable.premises to the conclusion that physicalism is false.
And that, after all, is about as good an objection as
one could expect in this area of philosophy.

(ii) Churchland’s second objection (24/5) is that
there must be something wrong with the argument,
for it proves too much. Suppose Mary received a
special series of lectures over her black-and-white
television from a full-blown dualist, explaining the
“laws” governing the behavior of “ectoplasm” and
telling her about qualia. This would not affect the
plausibility of the claim that on her release she learns
something. So if the argument works against physi-
calism, it works against dualism too.

My reply is that lectures about qualia over black-
and-white television do not tell Mary all there is to
know about qualia. They may tell her some things
about qualia, for instance, that they do not appear in
the physicalist's story, and that the quale we use ‘yellow'
for is nearly as different from the one we use ‘blue’ for
as is white from black. But why should it be supposed
that they tell her everything about qualia? On the other
hand, it is plausible that lectures over black-and-white
television might in principle tell Mary everything in
the physicalist’s story. You do not need color television
to learn physics or functionalist psychology. To obtain
a good argument against dualism (attribute dualism;
ectoplasm is a bit of fun), the premise in the knowledge
argument that Mary has the full story according to
physicalism before her release, has to be replaced by a
premise that she has the full story according to dualism.
The former is plausible; the latter is not. Hence, there is
no “parity of reasons” trouble for dualists who use the
knowledge argument.

(iii) Churchland's third objection is that the
knowledge argument claims “that Mary could not
even imagine what the relevant experience would be
like, despite her exhaustive neuroscientific knowl-
edge, and hence must still be missing certain crucial
information" (23), a claim he goes on to argue against.
But, as we emphasized earlier, the knowledge argu-
ment claims that Mary would not know what the
relevant experience is like. What she could imagine is
another matter. I f her knowledge is defective, despite
being all there is to know according to physicalism,
then physicalism is false, whatever her powers of
imagination.