The “hard problem”
Whether by
design or not, the article marks the thirtieth anniversary since David Chalmers
introduced the phrase “hard problem of consciousness” to label what has in
recent analytic philosophy of mind become a focus of obsessive attention. Introducing the problem, Kuhn notes:
Key indeed are qualia, our internal, phenomenological, felt
experience – the sight of your newborn daughter, bundled up; the sound of
Mahler's Second Symphony, fifth movement, choral finale; the smell of garlic,
cooking in olive oil. Qualia – the felt
qualities of inner experience – are the crux of the mind-body problem.
Chalmers describes qualia as “the raw sensations of experience.”
He says, “I see colors – reds, greens,
blues – and they feel a certain way to me. I see a red rose; I hear a clarinet; I smell
mothballs. All of these feel a certain
way to me. You must experience them to
know what they're like. You could
provide a perfect, complete map of my brain [down to elementary particles] – what's
going on when I see, hear, smell – but if I haven't seen, heard, smelled for
myself, that brain map is not going to tell me about the quality of seeing red,
hearing a clarinet, smelling mothballs.
You must experience it.”
Those last
two sentences indicate why qualia are
regarded by so many contemporary philosophers as problematic. The problem has to do with the metaphysical
gap that seems to exist between physical facts on the one hand (including facts
about the brain) and facts about conscious experience on the other (especially
facts about qualia).
The nature
and reality of this gap has been spelled out in various ways. Consider Chalmers’ famous “zombie
argument.” It is possible at
least in principle, he says, for there to be a world physically identical to
our own down to the last particle, but where there are none of the qualia of
conscious experience. Thus, in this
imagined world, there are creatures who are not only anatomically but also
behaviorally identical to us, in that they speak and act exactly as we do in
response to the same stimuli. But they
possess no inner life of the kind characterized by qualia. They are “zombies” in the technical sense
familiar to readers of contemporary work in the philosophy of mind (a sense
very different from that familiar from Night
of the Living Dead and similar movies).
But if they can be physically identical without possessing qualia, then
the facts about qualia must be something over and above the physical facts.
A related
argument known as the “knowledge
argument” was famously put forward by Frank Jackson. Imagine Mary, a scientist of the future who,
for whatever reason, has spent her entire life in a black and white room, never
having experiences of colors. She has,
nevertheless, through her studies come to learn all the physical facts there
are to know about the physics and physiology of color perception. For example, she knows down to the last
detail what is going on in the surface of a red apple, and in the eyes and
nervous system, when someone sees the apple.
Suppose she leaves the room and finally comes to learn for herself what
it is like to see red. In other words,
she comes for the first time to have the qualia associated with the conscious
experience of seeing a red apple. Surely
she has learned something new. But
since, by hypothesis, she already knew all the physical facts there were to
know about the situation, her new knowledge of the qualia in question must be
knowledge of something over and above the physical facts.
As you might
expect, the lesson many draw from these arguments is that materialism, which
holds that the physical facts are all the facts there are, is false. And this is taken to show in turn that
consciousness will never be explicable in neuroscientific terms. But while this certainly makes qualia a
problem for the materialist, you might wonder why they would be a problem for
anyone else. Can’t the dualist happily
take these implications to be, not a problem, but rather a confirmation of his
position? But it’s not that simple. For arguments like the zombie argument also
seem to imply that qualia are epiphenomenal, having no causal influence on the
physical world. And if qualia have no
causal influence on anything we do or say, how are we even talking about
them? Indeed, how can we know they are
really there?
How to
resolve such puzzles, and determining whether it is materialism, dualism, or
some alternative view that will survive when they are resolved, is what the
“hard problem” is all about. An enormous
amount of ink has been spilled on it in recent decades, as Kuhn’s article shows. Now, philosophical work can often be of great
value even when it is based on erroneous presuppositions, because it can teach
us about the logical relationships between certain concepts, and the
consequences of following out consistently certain philosophical
assumptions. That is why it will always
be important for philosophers to study thinkers of genius who got things badly
wrong (which would in my view include Heraclitus, Parmenides, Zeno, Ockham,
Descartes, Spinoza, Leibniz, Berkeley, Hume, Kant, and many others).
In my
opinion, the literature on the hard problem is of value in just this way. We learn from it important things about the
relationships between key philosophical ideas, such as the conceptions of
matter and of consciousness that have dominated modern philosophy. And it shows us, in my view, that materialism
is false, since the conception of matter the materialist operates with rules
out any materialist explanation of consciousness, and denying the existence of
consciousness in order to get around this problem would be incoherent. This literature also illuminates the problem
that post-Cartesian forms of dualism have in explaining
the tight integration between mind and body that everyday experience
reveals to us to be real.
Origin of the problem
All the
same, the so called “hard problem” is, in my view, a pseudo-problem that rests
on a set of mistakes. There is a reason
why ancient and medieval philosophy knew nothing of the “mind-body problem” as
modern philosophers conceive of it, and nothing of the so-called “hard problem
of consciousness” in particular. And
it’s not because they somehow overlooked some obvious features of mind and
matter that make their relationship problematic. It’s because the problem only arises if one
makes certain assumptions about the nature of mind and/or matter that ancient
and medieval philosophers generally did not make, but modern philosophers often
do make.
Points like
the ones to follow have often been made not only by Aristotelian-Thomistic
philosophers like me but also by Wittgensteinians like Peter
Hacker and Maxwell Bennett and Heideggerians like Frederick
Olafson. The key moves that
generated the so-called mind-body problem can be found in Descartes, so that
Thomists, Wittgensteinians, Heideggerians, and others commonly characterize
them as “Cartesian.” But variations on
these moves are found in early modern thinkers more generally.
On the side
of the body, modern philosophy introduced a conception of matter that is
essentially reductionist and mathematicized. It is reductionist insofar as it essentially
takes everyday material objects to be aggregates of microscopic particles. A stone, an apple, a tree, a dog, a human
body – all of these things are, on this view, really “nothing but” collections
of particles of the same type, so that the differences between the everyday
objects are as superficial as the differences between sandcastles of diverse
shapes. The new conception of matter is
mathematicized insofar as it holds that the only properties of the microscopic
particles are those that can be given a mathematical characterization. This would include size, shape, position in space,
movement through space, and the like, which came to be called the “primary
qualities” of matter.
With color,
sound, heat, cold, and other so-called “secondary qualities,” the idea was that
there is nothing in matter itself that corresponds to the way we experience
them. For example, there is nothing in
an apple that in any way resembles the red we see, and nothing in ice water
that in any way resembles the cold we feel.
The redness and coldness exist only in our experience of the apple and
the water, in something like the way the redness we see when looking through
red-tinted glasses exists only in the glasses rather than in the objects we see
through them. Physical objects, on this
conception, are nothing more than collections of colorless, soundless,
odorless, tasteless particles. This
includes the brain, which is as devoid of these qualities as apples and water
are.
On the side
of the mind, meanwhile, the modern picture makes of it the repository of these
qualities that are said not truly to exist in matter. Redness, coldness, and the like, are on this
view not the qualities of physical things, but rather of our conscious
experiences of physical things. They are
the “qualia” of experience. Often
associated with this view is an indirect
realist theory of perception, according to which the immediate objects of
perception are not physical objects themselves, but only mental representations
of such objects. For example, when you
see an apple, the immediate object of your perception is not the apple outside
you, but rather an inner representation of it.
The situation is analogous to looking at someone who is ringing your
doorbell through a security camera that is generating an image of the person on
a computer screen. What you are directly
looking at is the screen rather than
the person, and the colors you see on the screen are strictly speaking features
of the screen rather than the person
(even if they are caused by something really there in the person).
On the
indirect realist theory of perception, conscious experience is experience of
the inner “screen” of the mind itself rather than of the physical world. The physical world is the cause of what we see on this inner
screen, just as the person ringing your doorbell is the cause of what you see
on your computer. But we have no direct
access to it, and can know it only by inference from what we see on the inner
screen. Our awareness of the screen
involves something called “introspection,” which is analogous to perception
except that its objects are purely mental and known directly, whereas the
objects of perception are physical and known indirectly. For example, by introspection you directly
know your experience of the apple and the reddish, sweet, fragrant, etc. qualia
of this experience. Perception involves
indirect knowledge of an external physical object that is the cause of your
having this experience and those qualia.
The mind as
conceived of on this picture is often called the “Cartesian theater.” The reductionist-cum-mathematicized
conception of the physical world I described is often called the “mechanical
world picture.” The modern mind-body
problem is essentially the problem of determining how these two pictures are
related to one another, which is why no such problem existed in ancient and
medieval philosophy (or at least not in its mainstreams, though the ancient
atomist Democritus noted
a paradox facing his own position that is at least in the ballpark).
The problem
is that, on the one hand, since the Cartesian theater is characterized by
properties that the mechanical world picture entirely extrudes from the
material world, that theater itself cannot be part of the material world. Thus are we left with Cartesian dualism or
something in its ballpark. But on the
other hand, the separation between them is so radical that it becomes utterly
mysterious how the Cartesian theater can get into any sort of epistemic or
causal contact with the mechanistically described material world. Thus are we left with skepticism and with the
interaction
problem or something in its ballpark.
The “hard
problem of consciousness” is just the latest riff on this post-Cartesian
problematic. On the one hand, it is
said, neuroscience can shed light on the relatively “easy problems” about how
neural processes mediate between sensory input and bodily behavior, but not on
the “hard problem” of why any of this processing is associated with
qualia. On the other hand, it is said, it
is hard to see how qualia could be other than epiphenomenal given the “causal
closure of the physical.” The former
point recapitulates traditional Cartesian arguments against materialism and the
latter recapitulates the interaction problem the materialist traditionally raises
against the Cartesian.
Dissolution of the problem
From the
point of view of Aristotelians, Wittgensteinians, Heideggerians and others, what
is needed is, not further efforts to try to find a way to stop this merry-go-round,
but rather not to get on it in the first place. In particular, we need to abandon the background
modern philosophical assumptions that generate the “hard problem of consciousness”
and other variations on the mind-body problem.
For instance, we need to reject the reductionist-cum-mathematicized
conception of the material world we’ve inherited from early modern philosophy’s
mechanical world picture. With natural
substances, it is simply a mistake to think of them as no more than the sum of
their parts, and to suppose that to understand them involves determining how
their higher-level features arise out of lower-level features in a strictly bottom-up
way.
In the case
of a human being or non-human animal, it is a mistake to look for consciousness
at the level of the particles of which the body is made, or at the level of nerve
cells, or even at the level of the brain as a whole. Consciousness is a property of the organism as a whole. The mathematicized description of matter that
the physicist gives us, and the neural description the physiologist gives us,
are abstractions from the organism as
a whole, useful for certain purposes but in no way capturing the entirety of
the organism, any more than a blueprint captures all there is to a home. We should no more expect to find
consciousness at the level of physics or neuroscience than we should expect to
find Sunday dinner, movie night, or other aspects of everyday home life in the
blueprint of a house.
We should
also reject the assumptions about perception and introspection inherited from post-Cartesian
philosophy of mind. As Bennett and
Hacker show in detail in their book Philosophical
Foundations of Neuroscience and elsewhere,
discussions of the hard problem of consciousness routinely characterize the
relevant phenomena in ways that are not only tendentious, but bizarre from the
point of view of common sense no less than of Aristotelian and Wittgensteinian philosophy.
For example,
consider Chalmers’ remark, quoted above, that seeing a red rose, hearing a
clarinet, and smelling mothballs all “feel a certain way.” It is common in the literature on qualia and
consciousness to see claims like this.
The idea seems to be that different kinds of conscious experience are
differentiated from one another insofar as each has a unique “feel” to it. But this is not the way people normally
talk. Suppose you asked the average
person what it feels like to see a red rose, hear a clarinet, or smell
mothballs. He might suppose that what
you had in mind was whether these perceptions evoked certain emotions or
memories or the like. For example, he
might imagine that what you are wondering about is whether seeing the rose evokes
a feeling of longing for a girlfriend to whom you once gave such a rose, or
whether hearing the clarinet evokes happy memories of first hearing a Benny
Goodman record, or whether smelling mothballs generates a feeling of
nausea.
Suppose you
said to him “No, I don’t mean anything like that. I mean, what is the feel that the experience of seeing red has even apart from that
sort of thing, and how does it differ from the feel that the experience of hearing a clarinet has?” He would likely not know what you are talking
about. In the ordinary sense of the word
“feel,” it doesn’t “feel like” anything to see a red rose or hear a clarinet. Seeing an object is one thing, hearing a
clarinet played is another, and “feeling” something (like an emotion) is yet
another thing, and not at all like the first two. Discussions of qualia routinely take for
granted that there must be some special “feeling” that demarcates one experience
from another. But as Bennett and Hacker
note, that is not how we ordinarily do in fact distinguish one experience from
another. Instead, we distinguish them by
reference to the object of the
experience (a rose versus a clarinet, say) or the modality of the experience (seeing as opposed to hearing). There is no “feel” on top of that that plays
a role in distinguishing one experience from another.
Similarly,
it is often said that each experience has a distinct “qualitative character” to
it. There is, we are told, a “qualitative
character” to an experience of seeing one’s newborn daughter that is different
from the “qualitative character” of an experience of smelling garlic cooking in
olive oil. But as Bennett and Hacker
point out, this too is an odd way of speaking, and certainly not what the ordinary
speaker would say. To be sure, seeing
one’s newborn daughter may cause one to feel affectionate, and smelling garlic cooking
in olive oil may make one hungry. In
that sense there is a different feel or qualitative character to the
experiences. But all this means, as
Bennett and Hacker stress, is that person
feels a certain way as a result of the experiences. It’s not a matter of the experiences themselves possessing some sort of “feel”
or “qualitative character.”
Then there
is the fact that in discussions of the hard problem, it is constantly asserted
that one’s experiences involve a
reddish color, a garlicky smell, and so on.
But here too, that is simply not the way people ordinarily talk. They would say that the rose is red, not that their experience
of the rose is red, and that the garlic
has a certain distinctive smell, not that their experience of garlic does.
Common sense treats colors, smells, and the like as qualities of things
out there in the physical world, not as the qualia of our experience of that
world.
Now, these
odd ways of talking become intelligible (sort of, anyway) if one thinks of the
mind on the model of the Cartesian theater.
Suppose that what we are directly aware of are only inner
representations of physical things, rather than the things themselves. Then it might seem that we cannot entirely distinguish
different experiences by reference to the objects or modalities of the
experiences. For the experiences could,
on this model, be just as they are even if the physical objects didn’t exist
and indeed even if the organs associated with the different modalities (eyes,
ears, etc.) didn’t exist. How to
differentiate them, then? Positing a
unique “feel” or “qualitative character” for each experience might seem
necessary. Similarly, if it is only our
own experiences, rather than physical things themselves, that we are directly
aware of, then it is understandable why it would seem that in experiencing a
reddish color, a garlicky smell, etc. we are encountering the qualia of experiences rather than the qualities
of physical objects.
Aristotelians,
Wittgensteinians, Heideggerians, and others would say that this way of carving
up the conceptual territory is wrong, and that common sense is right. Of course, others would say that common sense
has it wrong, and that post-Cartesian philosophy was correct to go in the
direction it did. The point, though, is
that the “hard problem of consciousness” is not something that arises just from
a consideration of the relevant phenomena.
Rather, it is an artifact of a certain set of philosophical assumptions
that are read into the
phenomena. And those assumptions are by
no means unproblematic or unavoidable.
Indeed, the fact that they generate the “hard problem of consciousness”
is itself a good reason to question them.
(I have argued against the mechanical world picture and the Cartesian
theater conception of the mind in several places. For example, I do so at length in Aristotle’s
Revenge, and also in Immortal
Souls, in chapters 6 and 7 especially.)
All the same, the contemporary debate about the “hard problem” remains worthy of study – not because it teaches us where the truth about human nature lies, but rather because it illuminates the nature and consequences of certain very common and tenacious errors.