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The Philosophy of Mind Guidebook 2010

Chapter 8: Property Dualism, Biological Naturalism and Epiphenomenal


Chapter 8
: Property Dualism, Biological Naturalism


Property dualists accept that all substances are physical but not that all properties are.
What does this mean? It means that complex enough bits of physical stuff realise or
instantiate certain special mental properties. Why believe this? Qualia. The tast
e of a glass
of wine is something that cannot be treated as a physical property of any complexity. It is
just too different. There is a real

between the physical and the phenomenal.

One way of cashing this idea out is by saying that the mind

the br
ain but we are mistaken
in trying to fit mental properties into the same bed as physical properties: they are

properties but not like other physical properties. A person is conscious thanks to the activity
of his neurons. The property he has of bei
ng conscious must be accepted as a natural
property. We cannot however analyse the essential subjectivity of consciousness away into
some complex of objective physical properties. Such is Searle’s
Biological Naturalism

Alternatively, mental properties ar
e like decoration. Drinking the wine activates neurons and
the property of a distinctive taste is instantiated. It is my neurons that make me go back for
more, though. The taste does no work. This view is called Epiphenomenalism

The problem with the forme
r view is its mystery: it seems to be a form of property dualism
without admitting it. The problem with the latter is that it flies in the face of the obvious. It

the taste that is responsible for me choosing that wine.

Substance Dualism and Property Du

dualist believes that the mind is a non
physical substance: something that
exists in its right, independently of physical stuff. Pretty much no
one believes that there
exist such non
physical entities today. The physicists are the people
to turn to for a
catalogue of the basic ingredients of reality out of which everything is made.


dualist says that all substances are physical but some instantiate non
properties, such as qualia. Let us remind ourselves about them.


Qualia are properties of experiences. Traditionally, they have been considered in the
following way. They are
, as only I can have this taste. I can give you the same
glass of wine so that you have a separate taste
sensation sensation but I ca
n’t give you my
taste. Furthermore, perhaps you taste it differently (and how could I know?). They are
available to introspection
. You can consider your experience, relish the taste, and discern
the flavours of toast, liquorice and mouldy Wellington boots.

They are

to the
experience in that the experience couldn’t be that experience without them. They are

in that they do not represent anything. The ruby
coloured sensation does not
represent the ruby colour of the wine. This is beca
use many think that there is a very weak
connection between being able to perceive the wine and having that sensation. You don’t
need to have that sensation to perceive the wine: perhaps dogs and computers and other
people indeed don’t have that sensation.

We might say instead that they are the
The Philosophy of Mind Guidebook 2010

Chapter 8: Property Dualism, Biological Naturalism and Epiphenomenalism



to physical properties: the particular ways we (perhaps singularly) experience
physical properties such as the chemical structure of the wine responsible for its colour and
taste. Finally, people
often say they are
. There’s no way to describe or re
the colour you see when you see the wine. To convey it to someone, you have to get them
to look at the glass of wine and be struck by the same ineffable ruby sensation as you are.
e often say that you had to see it or taste it or hear for yourself. But we might doubt
this. A wine
taster and a writer are both able to convey much about how things taste, look
and feel.

Intentionality and Consciousness
: Two Problems and a Gap

phenomenally conscious experience is one with qualia. To be phenomenally conscious in
general is to be able to have such experiences. Our experiences come together in our
waking lives into an integrated whole: we may call this a global phenomenal experienc
e of
which individual experiences are elements. Alongside phenomenal consciousness, we have

consciousness and

conscious. To say that a state is access
conscious is to say (roughly) that is poised for use in reasoning and speech. T
o say that a
creature is self
conscious is to say that it has a concept of itself as a thing in the world. A
creature with access
conscious states and the concept of self is an intelligent creature
which will have

states: those that represent or are about things.

It may be that intentionality and the other forms of consciousness are equally rooted in the
possession of non
physical properties. Yet many philosophers are relatively more optimistic
about them that
about phenomenal consciousness. In the now
famous distinction of David
Chalmers, qualia constitute the ‘hard’ problem in the philosophy of mind; intentionality (and
reasoning) the ‘easy’ problem.

Why be a property dualist? Because you think that the


that exists between
mental and physical phenomena is so wide that it must be a
metaphysical gap
. Let us
(re)visit three famous thought
experiments that could be called on for support.

Leibniz’s Mill

We have met the mill twice now.
Leibniz’s poin
t, you will recall,
is that if we could examine a
thinking machine

and we can consider the brain to be such a thing

it would be an utter
mystery how it did it. We would see
mechanical activity

but no
intellectual activity

. Leibniz did not
understand that the brain is an electrochemical entity but his point
remains. An examination of the brain would not make us ‘see’ how it thinks or feels.

Although in some senses a pioneer of the very concept of a computer, Leibniz could not
have conceived

of the computers we have today. Leibniz would have been astonished at
their abilities. What computers help us to see is how reasoning can take place. A computer
processes data according to strict rules. Reasoning is a rule
governed process. A computer

internal states that represent. Intentional states are representational. At present, a
computer’s representational states are typically parasitically representational. The data in a
computer doesn’t represent anything to

but to
. But, runs the though
t, if we could fit a
computer with eyes and ears to turn it into a robot, it could make its own representations
and think by processing them. Very many philosophers think that computers are what
makes the easy problem relatively easy: we have by no means c
racked the problems of
representation and reasoning
but we’re on the right track

The Philosophy of Mind Guidebook 2010

Chapter 8: Property Dualism, Biological Naturalism and Epiphenomenalism


Leibniz’s Mill has more force with sensations. To be told that the activity of a certain
selection of neurons

the sensation of vanilla leaves us no less puzzled. This ‘ha
problem is famously highlighted by two more thought

Nagel’s Bat
Jackson’s Mary

and Chalmers’ Zombies

Nagel (1974) asks us to imagine a time when we have complete knowledge of a bat’s
neurophysiology. We are able to tell by monitoring the
bat’s brain, in real time, how it will
move, what it is detecting and so on. Yet none of this knowledge will help us realise
what it
feels like to be

a bat

what it feels like to echolocate things in our environment.

Jackson (1983) has a similar idea wit
h Mary:

Mary is a brilliant scientist who is, for whatever reason, forced to investigate the world from
black and white room via a black and white television monitor. She specializes in the
neurophysiology of vision and acquires, let us suppose, all the
physical information there is
to obtain about what goes on when we see ripe tomatoes, or the sky, and use terms like
‘red’, ‘blue’, and so on. She discovers, for example, just which wavelength combinations from
the sky stimulate the retina, and exactly how

this produces

the central nervous system
the contraction of the vocal chords and expulsion of air from the lungs that results in the
uttering of the sentence ‘The sky is blue’.… What will happen when Mary is released from
her black and white room or is given a color te
levision monitor? Will she

anything or
not? It seems just obvious that she will learn something about the world and our visual
experience of it. But then is it inescapable that her previous knowledge was incomplete. But
she had

the physical infor

there is more to have than that, and Physicalism is

The common argument is this:


We can have complete knowledge of the physical facts about brain and everything
else physical of relevance, such as the reflectance properties of the sur
faces of
different physical objects.


Nevertheless, we do not have complete knowledge of all the facts about colour
vision or echolocation

we do not know how it feels.


So, not all facts are physical facts.

So, the view that the world is ultimately and ex
haustively physical


is false.

Chalmers’ Zombies.

Finally, Chalmers (1994) makes heavy use of zombies. A zombie is something physically
and/or behaviourally identical to a human but which lacks an inner phenomenal life.
Chalmers argues that we can coherently conceive of such things.

Chalmers puts the po
int in terms of supervenience. The chemical, biological, economic and
so forth supervene on the physical. Consider making a physical duplicate of this world. Now
ask yourself whether you could duplicate the atoms but not the chemicals. Impossible! If
you d
uplicate the mass of atoms in the sea, you duplicate the sea and the chemicals in it.
Imagine duplicating the atoms in a storm but not the storm. Again, this seems impossible.
Imagine duplicating the atoms composing everything in our entire society but not

institutions of government. Impossible again. But we can imagine a duplicates of the people
that lack phenomenal consciousness.

Can we? Here’s one of his lines of argument. John Locke wondered if two human beings
could be functionally identical but h
inverted qualia
. When Bill experiences red, Ben
The Philosophy of Mind Guidebook 2010

Chapter 8: Property Dualism, Biological Naturalism and Epiphenomenalism


experiences blue; when Bill experiences yellow, Ben experiences green; and so on. Of
course, these differences are purely internal and never show up in behaviour. They both
have learned English by observi
ng the classifications other people make. They both senses
the similarities between similarly
coloured things. So they both apply the same words

“red”, “green”, “blue”, “yellow”

to the same things.

Now take this one step further. If inverted qualia ar
e possible, what about
absent qualia
Since we can have the same behaviour without the same qualia, why not suppose they can
be wholly absent. Such creatures would then be zombies: functionally identical but without
an inner life.

As it happens, we do not

need to imagine too much. We need simply to consider the
phenomenon of
. For over a century, scientists have known that the occipital
lobes of the brain are centrally involved in visual perception. Experiments on monkeys
showed that bits of the
occipital cortex can be removed leaving visual abilities impaired but
not destroyed. Yet when a human being had that part of the cortex removed (to remove a
tumour), he reported that he was blind. The same was true in other cases that came to light.
This i
s clearly puzzling. The monkeys behaved as if they were still seeing and yet the
humans claimed to be blind. Did it mean that their brains were not alike? Surprisingly, no.
Experiments on the blind subjects showed that they could discriminate visually with
seeing. Asked to guess the location of a visual stimulus, they guessed far above chance.
Such people suggest that there can be visual perceptual experiences without visual qualia.

You might say that these cases show that zombies may be functionally po
ssible and even
physically possible but they do not show that zombies could be physical duplicates of us.
The blindsight people do not have the same brains, for example. But this merely highlights
the problem. We can see no special connection between neuro
ns in the V1 area of the
visual cortex and qualia; they are
just like all the other neurons (except in a different place)

To put things theologically, according to Physicalists, all God had to do to create our world
was to create the basic stuffs of phys
ics and the basic laws of nature: everything else

chemistry, meteorology, etc.

was thereby fixed. According to Chalmers, Nagel and
Jackson, had God just done that, our world would be physically indistinguishable from the
one we know. The difference is
that ‘we’ would all be zombies. So, in addition, God had to
‘add in’ non
physical mental properties too.


and Emergentism

If physicalism is false and substance dualism is too, then we are left saying that there are
physical properties.
What is their nature?

According to Epiphenomenalism, such properties are instantiated by complex physical
system but lack causal powers. That is, they are caused but do not cause. Why would
someone hold such a view? If one accepts that the completeness of


that there is
a complete and sufficient physical cause for every physical effect, then non
properties cannot be allowed to do any work. To

accept the completeness of physics

to be a physicalist is traditionally to be an inte
ractionist dualist. And this means that
one has to accept substance dualism. Which no
one wants to do. So, the position we are
left with once we

substance dualism but

the arguments above is

The only alternative is to

cept the completeness of physics and reject dualism but to
keep interactionism. How? Emergentism is the view that physical systems of a sufficient
complexity, instantiating various physical properties, have non
physical properties ‘emerge’
The Philosophy of Mind Guidebook 2010

Chapter 8: Property Dualism,

Biological Naturalism and Epiphenomenalism


from them that m
anage to be causally active in a way that means they somehow mesh with
physical properties to give us a causal story without gaps and overdetermination.

Emergentism is recently back in fashion but for a long time, it was considered a strange
view as it s
eemed to be unable to avoiding collapsing into something else. If the non
physical properties ‘emerge’, then they can’t be reduced to the physical. But what is this
‘emergence’? Our brains started off as (relatively) simple physical things and at some poin
physical properties somehow came onto the scene: how? And how do they do causal
work (e.g. it is the

that causes my scream) when there is a pattern of neural activity
that seems to be a complete causal story whilst somehow being rooted in the ne
structure that is the brain (whilst not being reducible to it!)? Emergentists have their answers
but we shall not pursue them here

The Gap: Epistemological or Metaphysical?

A Metaphysical Gap

Dualists say that there is a gap between the mind and the b
: a metaphysical gap.
Substance dualists say that they are distinct substances; property dualists that physical
brains instantiate non
physical properties.

Descartes’ Conceivability Argument
: the essential natures of mind and body are
distinct: I can c
onceive of myself lacking a mind but not a body.

Descartes’ Divisibility Argument
: the essential natures of mind and body are
distinct: a mind is not divisible: a mind is a unified subjective consciousness that we
can discern aspects of in the way I can
discern the top and bottom halves of a
sphere. A body is divisible.

Leibniz’s Mill
: a third
personal perspective on the brain will yield mere structural
and functional knowledge; it will tell us nothing about the first
personal nature of

el’s Bat
: no amount of knowledge of a bat’s brain will tell us what it feels like to
be a bat.

Jackson’s Mary
: no amount of knowledge about colour and colour
perception will
enable Mary to know what it is like to see red.

Chalmers’ Zombies
: we can


identical creatures
with inverted qualia and absent qualia

indeed, blindsight suggests that these
possibilities are not outlandish.

Kripke’s Necessity Argument
: if mental states are brain states, they are so
necessarily. But t
his goes against our multiple realisability intuition. Furthermore, we
can’t explain away the intuition that mental states could not be brain states by saying
that creatures lacking brain states could have mental states similar to but not
identical to ours
; there is nothing (e.g.) similar to pain that is not pain.

How does the Monist reply?

Monists have to find ways of replying to these arguments. The basic move is to say the gap
is epistemological, not metaphysical. We simply do not currently

e relationship
between the mind and the brain. Once upon a time, we did not think living creatures could
be composed out of ‘inert’ matter; now we understand that they are and how it happens.

say that we have no reason to think that one day, we w
ill be in a similar position
with the mind and the brain.

often called ‘

by the optimists

argue that the connection will be forever beyond our understanding.

The Philosophy of Mind Guidebook 2010

Chapter 8: Property Dualism, Biological Naturalism and Epiphenomenalism


I shall return to the

distinction later. I’ll sta
rt by giving general lines of
response to the problems above and at the end, tie them to particular responses.

Do note that our concern here is with the hard problem:
phenomenal consciousness:
conscious experiences with phenomenal properties (qualia)
. We
’re not (so) interested in
intentional states.

Descartes & Leibniz

The traditional interpretation of the Conceivability Argument runs as follows.

I can clearly and distinctly conceive of my mind existing without my body. My clear
and distinct ideas reflec
t what is possible. So, my mind and body are distinct

Descartes claims two things

to have clear conceptions of mind and body

for conceivability to reflect possibility (for thought to accurately reflect reality).

Descartes was criticised on b
oth points during his own lifetime..

Gassendi and Hobbes questioned whether he understood what mind and matter

Arnauld challenged the move from conceivability to possibility: a mathematician may
suppose that not all right
angled triangles have the ‘
Pythagorean property’ but this is
not possible: necessarily, all triangles do. In general, we observe that we can have
two concepts of
things whilst labouring under the misapprehension that there is
thing: consider Lois Lane and Superman/Clark Kent
. And remember that the
conceivability of time travel doesn’t imply its possibility (the Grandfather Paradox).

It is certainly true to say that Descartes did not understand as much about mind and matter
as we do today. But this may not matter. We can read

Descartes as focusing on the
puzzling quality of subjective consciousness as the distinctive attribute of the mental, the
attribute which remains prominent and puzzling today despite all we have learned. Similarly,
even thought Descartes was wrong about t
he nature of matter

he thought the universe
was a plenum of infinitely divisible matter

we not have discovered anything about matter
which makes it any immediately easier to see how the physical matter of the mind
generates consciousness.

Indeed, this

is just what Leibniz was saying in a more directly way. Leibniz thought of the
brain as a mechanism: an entity composed of lots of parts that act on one another through
contact and transference of force. (Think of a watch.) His argument is simple. Suppose

could shrink ourselves small enough to wander around the brain. We woud observe of the
physical properties of things: their shape, their structure and their causal relations. None of
this seems to help us understand the nature of subjective consciousne
ss. There is a crucial
divide between the objective or ‘third
personal’ properties of things and the subjective or
personal’ properties. Leibniz was wrong about the nature of the brain, as it is an
electrochemical not a mechanism circuit. Neverthele
ss, his intuition remains powerful. It is
no clearer how the objective electrochemical properties could yield consciousness.

if these thoughts are right, then Descartes and Leibniz can argue that what they understand
clearly enough about the mind

tive consciousness

can be conceived to exist
without the body/brain because there is no obvious connection between the two. But now
The Philosophy of Mind Guidebook 2010

Chapter 8: Property Dualism, Biological Naturalism and Epiphenomenalism


we press the Arnauld point: even so, you may simply be ignorant of the connection that

and must


Monists w
ill point out that we easily form distinct concepts of the same thing. Concepts are
formed within frameworks. Our ‘everyday’ or ‘folk’ framework classifies things in terms of
their relatively superficial phenomenal and functional properties.

is the s
tuff that


a certain way and which
boils at 100
freezes at 0
is essential for life

and so on.
O is a concept in our advanced chemical framework. We think of atoms and forces, not of
appearances and function.

Now we can make the cruci
al point:

When we discovered that water is H
this was an ‘a posteriori identity’:
something science proves to be true. It is not an a priori identity: something
discoverable by reflection on the concepts. Same with Clark Kent/Superman,
rus, lightning/electricity, etc. etc.

Monists will back this up with appeal to the
success of science

argument to say that, over
time, more and more has been explained as part of the physical world; it would be odd if the
mind was the only thing that could not be. It is further bolstered by the
causal closure
. We can explain ‘high
level’ causatio

cell divisions, window
drivers controlling cars, etc.

in terms of ‘low
level’ causation

the motion of atoms. All
causation is ‘ultimately’ physical. If we accept mind
body causation and we rule out over
determination, then mental states
must be physical states.

The idea that our concepts may misrepresent reality in a way that only

can cure is
the key point that monists make:

Optimists say that science will really ‘scratch the itch’: that it will make it properly
how neurons yield consciousness in a way that leaves us fully

optimists say that science will prove the identities but not in a way that leaves
us satisfied. Our concepts are simply rooted in different frameworks and there will
always be a d
egree of separation.


of reply

We have different concepts of mind and body: this is why I can conceive of my mind
existing without my body.

But conceivability does not immediately imply possibility: we can fail to see
understand how X and Y are co
ncepts of the same thing.

Sometimes, it is not philosophy that will provide the cure but science: the identity is
an a posteriori one, not an a priori one.

Nagel’s Bat

Nagel’s bat is clearly similar to Leibniz’s Mill. It is not
consciousness that are s
to have trouble imagining but that of a bat. The difference is important. A defender of Nagel
might reason thus:

Scientists and philosophers might one day announce that activity in neural area Z in
just is

the taste of vanilla. It is one of those a posteriori identities that we
have to accept but cannot get fully comfortable with. But we should not accept them
saying this! The problem is that we can see both sides of the equation: we know
what the taste of
vanilla is and what the brain activity is. But with the bat, we have
The Philosophy of Mind Guidebook 2010

Chapter 8: Property Dualism, Biological Naturalism and Epiphen


only one side of the equation: the brain side. The bat makes it really clear just how
wide the gap is. We cannot begin to think what echolocation feels like. We can’t
grudgingly accept th
at the bat’s qualia are chiropteran neural properties because we
don’t know what they are like.

A monist might reply by highlighting different ways of knowing. Consider the experience of
being a Roman soldier. Let us suppose you develop an interest in the

life such a person
would have led: what they would have worn, how they would have been educated, what
they would have eaten, and so on. Does this enable you to project yourself into that life? I
very much doubt it. It takes a lot of effort to recreate suc
h a different world. A good novel or
a film can take us a long way there but never all the way. Arguably, the only way to know
what it is like is to be there

to live it. This is of course impossible for us now.

Since all the facts cannot tell us what it

is like, should we conclude that there are non
properties? Of course not! A Roman soldier was a physical thing in
a physical world. We simply lack the power of imagination to translate the facts about his life
into the experience of

his life. The same goes, of course, for the bat.

Jackson’s Mary

Essentially the same reply can be made to Jackson. Mary’s knows all the physical facts but
is not able to translate them into the relevant experience.

The point is often put by saying that M
ary knows all the facts about colour but not in the
right way. Let us consider water and H
O again. There is one substance but two ways to
think about it: as water or as H
O. A child who learns about water is also learning about
O. But the child will not

realise this as it lacks the concept. He learns that water boils at
C. When he learns that H
O boils at 100
C, he is not learning any new fact about the
world. He is learning an old fact in a new way

via a new concept.

In the same way, Mary has a p
hysical concept of red thanks to all her learning. Everyone
else has a phenomenal concept of red: the concept that is activated not when you think
about red but when you

something as red. Mary either has that concept innately
and will have it ac
tivated for the first time when she sees the rose or doesn’t have that
concept but will learn it

will have a mental item built

when she sees the rose for the first

Opponents of this view claim that if Mary knows everything, she will know everyt
hing about
what happens in the brain when she sees red. She knows ‘from the outside’ what the

the mental item

will be like. Now, there is indeed a difference from knowing it
from the outside and from the inside

that is, when the concept is ac
But this is
precisely what needs to be explained: how activating the concept makes it ‘feel red’ or ‘taste
y’ or ‘sound trumpety’

Similarly, they will say, whilst it is hard to imagine what life would be for a Roman soldier, it
is hard, n
ot impossible. We could re
create the life at great expense. We could even bring
up a child in a fake Roman world so that at least it knows what it is like. But no matter what
we learn about the brain, we cannot know what it feels like to echolocate.


philosophers, such as Dan Dennett, have thought about making the bold response
that if we or Mary really did know everything there is to know about the brain, we would be
able to imagine what it is like.

We shall not pursue the more technical responses t
hat have been developed. You should
reflect on the Roman soldier example. You should ask yourself whether the difference
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Chapter 8: Property Dualism, Biological Naturalism and Epiphenomenalism


knowing the facts

living the life

is sufficient for us to say that there is new
knowledge about the world to be gained by l
iving the life

and hence there’s knowing we’re
missing about the bat and that Mary is missing

or whether it merely highlights the
impossibility of translating the facts into an experience.

Chalmers’ Zombies

For our purposes, the zombies do not present

anything radically new.

Some argue that zombies aren’t even conceivable. Daniel Dennett thinks that if we really
understood the brain better, we would see that we cannot make proper sense of creatures
like us lacking minds. He asks us to consider creatur
es that are physically identical to us but
lack the property of being alive. We can’t do it. Once upon a time, people thought they
could. Two hundred years ago, people did not understand how mere matter

inert stuff

could ever be alive. They could have
thought they could conceive of materially similar
creatures lacking the vital spark that we have that animates us. But they were simply
ignorant. In the same way, when we understand more, it will be no more possible to imagine
physical duplicates lacking c

The majority argue that they are conceivable but not possible. Once again, they appeal to
the idea that we are ignorant of the details of the mind
brain connection. Optimists believe it
will be explained. Non
optimists believe it will not be

Kripke’s Necessity Argument

At the heart of Kripke’s argument is the claim that there’s nothing pain
like that isn’t pain.
This being so, either pain
states are necessarily brain states and the multiple
intuition (MRI) is wrong or they are
not and it is right.

There are four ways to reply:

#1: Pain
states (phenomenal states in general) are brain
states. The Type
Type Identity
theory is true. The MRI is wrong.

A brave strategy but traditionally too brave. Why should neurons be so special?
Well, perhaps they just are. Who would have thought that having the atomic number
of 79 (=79 protons in the nucleus) makes something the shiny solid yellow metal we
know as gold whereas having an atomic number of 80

just one more!

makes you
into the si
lver liquid metal mercury. Why is this so? It ultimately just is.

#2: Pain
states are functional states.

Again, a brave strategy. Phenomenal properties are hard to understand functionally.
The inverted qualia thought experiment makes the point perfectly.

Surely it doesn’t
matter how our visual qualia are arranged so long as we make the sort of
discriminations. The particular ‘palette’ of colours that I paint the world with is
functionally irrelevant.

A consequence of this view is that the Chinese Nation,
for example, can be in pain
even if no Chinese person composing it is. This is hard to swallow.

#3: Pain
states are part
function, part physical.

Better. So, when it comes (e.g.) pain, we need to think of two distinct things:

The Philosophy of Mind Guidebook 2010

Chapter 8: Property Dualism, Biological Naturalism and Epiphenomenalism



The pain
: running a
way, screaming, etc.: this can be handled
functionally. You simply need to be a creature with the pain
program loaded
into your brain
hardware. It is all software; hardware is irrelevant.


The pain
: this depends on the hardware not the software. T
creatures in functionally identical pain
states may have different sensations
thanks to the different hardware (brains).


Will we understand the connection between the sensation and the brain
state? Again, we can choose to be optimists or mysterians.

ctionalists who pursue the two
level line can deny that the Chinese Nation have
a pain sensation: they are made out of the wrong sort of stuff. But they bite another
bullet: the fluffy kitten bullet. If a Martian can be in pain whilst lacking my brain, the
it will have a different sensation. For example, for Martians the sensation of pain
could be the sensation I have when I stroke a fluffy kitten. But that’s mad! How could
that be painful to anything?

#4: Pain
states are token
identical with
states, not type identical.

Better. Let us contrast the type
type and token
token with the example of books.
Suppose Steve has a copy of
Great Expectations
. Paul tells him that he does too.
Steve is a type
type theorist about books. So, he thinks th
at if Paul also has a token
of the type
Great Expectations
, he must have a physical token of the same physical
type. That is, he must have a copy physically identical to Steve’s. Furthermore,

that sort of physical copy can exist: necessarily, physical

of that

copies of Great Expectations. Such a view is of course mad. Paul can have a token
copy of a different physical type

one printed differently, one in French, perhaps
even a cartoon version.

Paul is a token
token identity theorist about books. He looks at his copy. He knows
that people can have physically different books that are still tokens of the same
novel type

i.e., copies of
Great Expectations
. Now, let us focus on Paul’s copy. If
ke is right, then this physical object, necessarily, is a copy of
. Well, what’s wrong with that? Isn’t this obvious? These words could
not be the words of any other novel!

In a similar way, we can agree that

Paul’s brain is in a cer
tain state that is a certain
mental state, then this is necessarily so; he could not have that exact same brain
state without the mental states. But


this implies nothing about other
people with the same mental state. They could have different


A problem for this is a general problem for the token
token identity theory. Not every
physical state can be a mental state. My shoelaces can be in no physical state that
makes them minded. So, the range of things that can instantiate menta
l properties
might be quite small. If so, then there’s a risk that we can indeed talk of a

physical state that is a type of mental state. For example, it may be that a big toe
can only be
configuration X of neurons or configuration Y of alien
eurons. If so,
then we are back with the type
type identity theory.


It is one of the advantages of Davidson’s theory that it avoids this problem for
intentional states. Davidson argued that rules someone possesses a network
of intentional states in virtue
of belonging to a community of rational beings
who can ascribe that someone those states. Very crudely, the nature of
intentional and physical states are so different that we can exclude any kind
of systematic type
type correlations.

The Philosophy of Mind Guidebook 2010

Chapter 8: Property Dualism, Biological Naturalism and Epiphenomenalism


Optimism and
ism (

An epistemological gap is a gap of understanding in this context. The mind

the brain but
we don’t fully understand how. We don’t understand exactly what consciousness is or how
the brain produces it. This is why we find it hard to see

how a bunch of divisible neurons,
considered ‘third
personally’ could give rise to an indivisible subjective consciousness. But
once upon a time we did not understand how mere matter could be alive.

reply says this and that we need to do
more research. One day, we will
understand. The non
optimistic alternative says the above but that more research won’t
help. The problem is that we’re just not smart enough to solve the problem. We’re like
badgers trying to do algebra. Why? Well, we have t
wo ways of thinking about things. We
have the ‘perceptual’ way and the ‘conscious’ way.

Let’s begin with the former. We are beings who think in visual and spatial terms. If I ask you
to think of an atom, you’ll probably picture a little collection of ball
s in a ‘solar system’. You
take familiar objects


and imagine them shrunk. Indeed, when you think of the solar
system itself, you take the same objects and imagine them inflated. Many people think of
abstract concepts like

in visual terms

in terms of collections of pebble or a
‘number line’. We think of the brain as a giant system of electrical scaffolding.

This way of thinking presents us only with the external or objective features of things, those
visible from the third
person. We can

also identify things as conscious phenomena: pains,
thoughts, desires. But these feel essentially first
personal. A desire is someone’s desire, a
pain someone’s pain. What we

is a means of thinking in a way that reconciles these
two ways

a way that

would enable us to see how the grey matter of the brain (thought of
personally) is the conscious mind (thought of first
personally). We have every reason
to believe that they

the same. We are simply victims of mind that can’t grasp the

Looked at positively, we simply have to accept that our limited minds make the mind
problem insoluble. Looked at negatively

by people who are optimists

this is

we simply give up and call the problem too mysterious to solve.

e Gap: What The Theories Say (in brief)

We have explored ways in which the monist can tailor his general line to the particular
argument, that general line being that the differences are conceptual not metaphysical. Let
us finish by re
organising what we h
ave said as ways the different monist theories we have
been looking at can respond.

Type Identity Theorist
: “mental state types are brain state types; we merely
have different concepts. If we’re optimists, we’ll understand how the brain produces
mind and resolve Descartes’ concerns and dispense with Leibniz’s Mill. As for Nagel’s Bat
and Jackson’s Mary, we say that even if we know how the brain produces phenomenal
states, to know what it is like requires you to ‘live’ them

which may be beyon
d our
imaginative powers. As for Kripke, we bite the bullet: necessarily, only brain states can be
mental states.

The Functionalist
: “
mental state types are, in general, functional types but phenomenal
states are tricky.

One route is to say they are func
tional too. (See Kripke #2.) If we’re optimists, we’ll
one day understand how this makes sense and solve all the puzzles. We can say
The Philosophy of Mind Guidebook 2010

Chapter 8: Property
Dualism, Biological Naturalism and Epiphenomenalism


with Bat/Mary that even if you understand the functional nature of phenomenal
states, you may not be able to project yourse
lf into them. And we’re happy to accept
that if pain is a functional state X, it is necessarily so.

A second route is to say that phenomenal states are part functional, part physical.
(See Kripke #3). If so, then the tricky ‘bit’ of the phenomenal state is

a physical state
of some sort. Again, we can be optimistic or non
optimistic about whether it can be
explained. Again, we can say that part of solving the Bat/Mary problems is that we
can’t imagine what it is like even if we do understand everything.


claim that mental states
are just

behavioural states. Understanding these is
all there is to understand.

even if you are don’t like dualism, this is crazy! Pain is clearly
different from pain behaviour.

Anomalous Monists

don’t have much
to say about sensations and consciousness as the
theory is really concerned with intentional mental states. They are token
token identity
theorists and could be optimists or non
optimists about the relationship between brain
states and mental

Biological Naturalists

say that we cannot reduce the first
person phenomena to third
person phenomena but we know that they are caused by the brain. If we are optimistic, we
will not be optimistic in the sense above. For such optimists think that one day w
e will
explain how first
personal states emerge from the brain in a reductive way. Optimism here
means that we will learn everything there is to know about how neural activity is correlated
with consciousness and sensation. And then we will simply say that



sensation of vanilla. Nothing more can be said. Alternatively, we can take the limited view
that there’ll be facts about the brain forever beyond our knowledge.


are typically optimistic: what we need to do to make prog
ress in the
philosophy of mind is swap our coarse vocabulary of sensations and qualia for a modern
vocabulary of neuronal
n patterns. Our shiny new theory will enable us to
understand how consciousness and qualia arise. Once again, Mary may still
be unable to
know what it is like because she hasn’t a powerful enough imagination to ‘turn on’ or create
the phenomenal

concept but there’s no new information to be learned. As for Kripke, we
would have to accept

but happily!

that the mind we have

uncovered without our new
theory could only be realised by a brain


It is important that it is knowledge about the world in some sense. By ‘living the life’ we trivially gain
knowledge about ourselves: we know that we are living the experience, that that last experience was
, and so on.


*We need to be a bit careful here with this example. The copy of Great Expectations

object could be another novel; we need merely imagine a language with the same words as English
but different meanings. The copy

interpreted physical object could not be: those

could not express a different novel… or could they? There’s a nice (very short) story by Jorge
Luis Borges called
Pierre Menard, Author of the Quixote

in which the fictional author Menard is

taken by Cervantes’
Don Quixote

that he decides to re
write it. He decides not to write another
version of it but become so involved with the world of the novel that he re
writes the entire novel line
line. The two novels are identical and yet diffe
rent; Menard’s

is “infinitely richer” than
Cervantes’. How? Because Cervantes’ and Menard have different perspectives. When Cervantes
writes in archaic Spanish, this is nothing special; it is the language of his time. When Menard does, it
is an ach
ievement. Cervantes draws upon things familiar to him in his time; Menard achieved the
greater task of recreating that perspective so as to create the novel from the 20h century. The short
story thus makes us question what it is to author a text: an author

cannot claim a body of words as
his own and his alone if Borges is right.