Dualism seems unsatisfactory, and behaviorism incomplete at best, while materialistic monism appears chauvinistic. How can we pro-ceed? In response to difficulties like those we just encountered in
Armstrong’s version of monism, it might be suggested that we con-sider a simple machine. A lever, for instance, is any object that has a fulcrum, can bear a load, and can have work applied to it. A wheel-barrow, a seesaw, even your arm are all forms of levers. Notice that in defining a lever I said nothing about what it has to be made of.
Granted, you won’t get far trying to make a seesaw out of butter at room temperature. On the other hand, so long as you use something fairly rigid it doesn’t matter what you choose: it can be wood, steel, granite, plastic, and so on. One might say that the lever is multiply real-izable: the description we have given of the lever can be realized, within limits, in a variety of material forms.
What we have said about levers suggests a way out of our chau-vinism problem about minds. Granted, minds are not as easy to define as levers. However, if a mental state can be characterized, at least in part, in terms of dispositions to behavior, then it might be suggested that any such state is that disposition plus some physical realization or other. Just as it doesn’t much matter what a lever is made of so long as it can do the job, so, too, on this approach it doesn’t much matter how a mental state is realized so long as it disposes its owner to behave in the relevant way. Clusters of neurons give one way in which the mental state might be realized, but that state might instead be realized in, for instance, silicon chips.
This is the doctrine of functionalism. The functionalist holds that a mental state M is a state of an entity (not necessarily an organism) produced by characteristic environmental stimuli, and in conjunction with other mental states, M tends to produce characteristic behavioral output. Functionalists typically add the further proviso that those states take some physical form or other.That is, while, strictly speak-ing, one can be a functionalist without requiring that the functional state in question be physical, most functionalists offer their position as an improvement on all the theories we have canvassed so far, and most hold that requiring a physical realization is necessary to achieve this gain. Let’s follow the majority of thinkers in this choice.
Functionalism has its virtues. For one, it’s not chauvinistic. It leaves open the possibility that in principle there may be a creature with a radically different internal structure from our own but which never-theless possesses cognitive, affective, or experiential states. In fact, functionalism doesn’t even require that mental states be realized in living creatures; for all we have said so far, a computer could realize a functional organization of a sort to give it a mind. Second, it improves upon Ryle’s form of behaviorism by offering a physical basis for the dispositions that he adduces in explaining mentality. In this way
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functionalism seems to combine the good things about Ryle’s behav-iorism and the identity theory, while eschewing the bad.
Another nice thing about functionalism is that it raises the fasci-nating question whether computers could think, feel, or experience.
In fact, functionalism is committed to the view that if a computer has the right sort of functional organization, it would be able to do all of these things. Some will find this implication welcome; others will find it so ghastly as to refute the theory that implies it. Let’s tread carefully here. First, to those who find the prospect of a “thinking machine”
disturbing, let’s be clear on whether this response is relevant. Many possible theories or findings might be disturbing. I would find it dis-turbing to learn that certain racial groups have characteristically higher or lower intelligence than those of the general population.Yet the fact that this might be disturbing would do nothing to refute the finding. Similarly, if functionalism implies that machines (if only those that are beyond our current technological limitations) can think, and that seems disturbing to you, then that is no skin off the back of functionalism. The functionalist might just reply: “Welcome to the desert of the real.”
Second, one could point out that there could not be a thinking machine because any “intelligence” it possesses would have to have been placed there by the engineers and programmers who built it.
This, however, does not seem to be a feature that distinguishes machines from us. After all, our genetic make up and environment (including the influence of our teachers and parents) have fed a great deal of information into our minds over a long period of time.That fact doesn’t seem to threaten our right to be called thinking things; nor should such a fact threaten the right of computers to this nomination.
Third, one could object that no machine could achieve the kind of creativity necessary for composing a great symphony, discovering a cure for a disease, painting a beautiful picture, proving a profound mathematical theorem, etc. This claim is, however, questionable on two grounds: First of all, plenty of us are entirely bereft of creative ability. Many people simply lack the capacity for these feats. Yet I doubt that one who makes this third objection really believes that those human beings who are not at all creative don’t really have minds. Furthermore, computers these days can do some pretty impressive things. Chess-playing computers can modify their pro-grams to take into account the strategic personalities of their oppo-nents. In addition, there are mathematical theorems that have only
been possible to prove with the aid of computers. I likewise see no bar in principle to the possibility of a computer composing some wonderful music; for all I know it has already been done.
The 1980s and 1990s witnessed a raging controversy over the question whether computers can think. Proponents of so-called arti-ficial intelligence contended that it is possible in principle for com-puters to think; their opponents were resourceful in suggesting things that computers cannot do. Now that the dust has begun to settle we can see that much of the controversy revolved around the experien-tial component of the mind. It is not at all clear what it would be for a computer to experience pain or for it to have a sensation of yellow.
Of course, one might hold that a computer can be possessed of cog-nition without having experiences as well. We need not get side-tracked with that issue, for the experiential component of the mind raises some of the most pressing philosophical questions of our day.
Consciousness
Functionalism goes a long way in accounting for many mental states that are associated with characteristic patterns of behavior. It seems an improvement over La Mettrie’s materialism, over Ryle’s behavior-ism, and over Armstrong’s identity theory. However, some mental states are not associated with any such patterns of behavior, and oth-ers that are so associated contain elements that still seem to be left untouched by a functional characterization. Consider a sensation such as I have when I look at something yellow in good light under nor-mal perceptual conditions. This sensation tends to be caused by my retina receiving light at a certain wavelength. It might also, in con-junction with other mental states, tend to produce characteristic behavior such as my uttering words like “yellow” if I am an English speaker. But this functional characterization of an experience of yel-low doesn’t seem fully to capture what is going on when I have that experience, because there is a distinctive quality to the experience of yellow, a quality that no other experience quite has and that doesn’t seem to manifest itself in my tendencies to behavior.
To grasp this point more vividly, imagine that the aliens that we mentioned earlier appear on Earth one day.They are extremely good investigators, and in little time they figure out the functional organi-zation of human beings. However, imagine also that these aliens have
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sensory systems radically different from our own.They lack eyes, but instead use sonar to echolocate their way around. In addition, they can often find things that are hidden to our own eyes because they have organs much like the ampullae of Lorenzini found in many species of shark, organs that enable them to detect electrical activity in living organisms and elsewhere. Sonar and the ampullae of Lorenzini are apparently the aliens’ only sensory organs; they lack smell, vision, hearing, touch, and taste. (As it happens, we don’t know whether they have proprioception.)
Consider the consequences of the aliens’ limited sensory capacity.
They have no idea what the yellowness of a lemon looks like. They have not the faintest clue of the smell of vanilla, or the sound of a trumpet. As a result, in spite of knowing the full functional organiza-tion of human minds, they know very little about how the world appears from our point of view. More generally, while the aliens might know everything there is to know about our physical makeup and functional organization, they are clueless as to what yellow lemons look like, how trumpets sound, and so forth. Because of that, they seem to lack a complete understanding of our minds. (Of course, we are in a symmetrical situation with respect to them; we have no idea what it would feel like to experience a thing through electrore-ception, and even a full neurophysiological description of alien brains won’t help us to get that knowledge.)
We are now face-to-face with one version of the problem of con-sciousness: Very broadly, the problem of consciousness strives to make sense of the possibility of conscious experience in a purely physical world.The case of the aliens makes vivid the fact that one can know all there is to know on the physical level without knowing what is going on at the experiential level. Yet an ability to get experiential knowledge out of physical information seems to be required if we are to understand the physical basis of consciousness. After all, it is one thing to say that having a central nervous system or some other suit-able physical realization is necessary for experience; it is quite another thing to say that adverting to what happens on the physical level can account for the nature of that experience. This latter is a stronger claim than the former, and the case of the aliens seems to show that the stronger claim is not true. They know all about us on the physi-cal level yet know very little about what our experiences are like.
The problem of consciousness is not just a challenge to function-alism, it is a challenge to the very idea that the world can be fully
understood in physical terms. Naturally, a dualist such as Descartes would, if he were alive today, smirkingly point out that he told us so;
perhaps we should never have taken materialistic monism seriously in the first place. On the other hand, as we have seen, dualism raises some mysteries of its own. Further, perhaps we can wriggle out of the problem of consciousness by suggesting that knowing such things as what a lemon looks like or what a trumpet sounds like are abilities rather than states of knowledge. After all, no reasonable person would criticize a physical account of how a bicycle works by complaining that we can know everything there is to know about how a bicycle works without knowing how to ride it. Knowing how to ride a bike is a skill, and if I lack this skill while still knowing the physics of bicy-cles I can’t lay this failing at the door of physics.
A parallel line of reasoning might apply to experience. I know what lemons look like and how trumpets sound. I can manifest these bits of knowledge by calling up the look or sound in imagination.
Barring that, I can manifest these bits of knowledge by showing that I can tell the lemon looks and the trumpet sounds from all the other experiences I might have. (If you have doubts about whether I know what a trumpet sounds like, present me with the sound of each wind instrument in an orchestra to see if I can detect the trumpet.) However, all these ways of manifesting knowledge boil down to abil-ities that I might possess. I am able to tell the lemon looks from the strawberry looks and the tomato looks; I am able to discriminate the trumpet sounds from the oboe sounds and piccolo sounds. If that is right, then knowing what an experience feels like is more like being able to ride a bicycle than knowing a bit of factual information.
This ability hypothesis (knowing what an experience is like is an ability, not a matter of possessing a piece of factual information) has come under heavy fire among students of consciousness, and some have gone so far as to hold that the very phenomenon of con-sciousness shows that a purely physical explanation of the world is impossible. Those who hold this pessimistic opinion don’t, in gen-eral, do so for the perverse pleasure of gainsaying the possibility of a purely scientific explanation of our world. Instead, many come to that conclusion reluctantly. Before reaching that drastic conclusion, however, I would suggest that we do well to be very clear about just what a physical explanation of the mind should give us. That ques-tion is a topic of current discussion among philosophers, neurosci-entists, and psychologists.
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Study Questions
1. In the first two of his Meditations, Descartes considers the possibil-ity that all of his beliefs are false. First, how do (a) illusions, (b) hallu-cinations, and (c) dreams sometimes bring about false beliefs in us?
Next, even if Descartes can somehow rule out the possibility that he is dreaming, what further, more troublesome, possibility would he have to rule out in order to be confident in even such apparently obvious beliefs as that he has a pair of hands?
2. Descartes argues that even if he cannot rule out this more trouble-some possibility, there is a first proposition about which he cannot be mistaken. What is the first proposition about which he believes he cannot be mistaken, and how does he show that he cannot be mis-taken about it?
3. Suppose you have a “second-order” belief about the contents of your own mind, such as a belief that might be expressed with the words, “I seem to see an apple before me.” (A “first-order” belief would be expressed as “There is an apple before me.”) Would that belief turn out to be wrong if, in fact, you are dreaming? Please explain your answer.
4. Please explain the indiscernibility of identicals. Next, Descartes holds that his essence consists entirely in his being a thinking thing (Meditations, p. 51). He seems to infer from this that it is in principle possible for his mind to exist without his body, indeed without his brain. Please explain how Descartes concludes from this observation that his mind and body are in fact distinct.
5. La Mettrie opposes Descartes’ dualism with a form of materialistic monism. How does he justify that position? How might Descartes respond to that attempted justification?
6. Explain what it is to commit a category mistake as Ryle construes that notion. Next, give a relatively simple example of a category mis-take.Why would Ryle charge Descartes with committing a category mistake? In your answer, please be sure to explain Ryle’s view that mental characteristics like “irritated” and “elated” refer to behavior and/or dispositions to behavior.
7. Armstrong agrees with Ryle in holding that mental characteristics may be defined in part in terms of behavior and dispositions to behavior. Why would Armstrong nevertheless charge Ryle with fail-ing to take a necessary further step, namely, assignfail-ing a “categorical”
basis to these dispositions? (In your answer it will be helpful to draw on analogy with dispositional properties of inorganic substances such as salt or glass.) Finally, after formulating this objection to Ryle, at what position concerning the relation between mind and body does Armstrong arrive?
8. Suppose one defines mental properties such as being angry or thinking about Toledo, as states of the central nervous system disposed to produce various kinds of characteristic behavior. Why might a position of this sort seem liable to a charge of chauvinism?
9. How does functionalism offer a theory of the mind that does not seem to succumb to the charge of chauvinism? Functionalism seems to imply that it is possible in principle for computers to think. Does that refute the theory? Why or why not?
10. Consciousness seems to be particularly difficult to explain in materialistic terms. Please explain why this is so.
Suggestions for Further Reading
Plato. Republic, translated by C.D.C. Reeve, 2nd edition. Indianapolis:
Hackett Publishing Company, 1992.
Descartes. Meditations on First Philosophy, translated by D. A. Cress.
Indianapolis: Hackett Publishing Company, 1993.
La Mettrie, Julien Offray de. Man a Machine, ed. Justin Lieber.
Indianapolis: Hackett Publishing Company, 1994.
Ryle, G. The Concept of Mind. Chicago: University of Chicago Press, 1984.
Rosenthal, D. Materialism and the Mind–Body Problem, 2nd edition.
Indianapolis: Hackett Publishing Company, 2000.
Lycan,W. Mind and Cognition: A Reader. Oxford: Blackwell, 1990.
Heil, J. The Philosophy of Mind. New York: Routledge, 2004.
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Wilson,T. D. Strangers to Ourselves: Discovering the Adaptive Unconscious.
Cambridge: Harvard University Press, 2002.
Turing, A. “Computing Machinery and Intelligence.” Mind, vol. 59 (1950), pp. 433–60.
Hodges, A. Alan Turing:The Enigma. New York: Simon and Schuster, 1983.
Irwin, W., ed. The Matrix and Philosophy: Welcome to the Desert of the Real. La Salle: Open Court, 2002.
———. More Matrix and Philosophy: Revolutions and Reloaded Decoded.
La Salle: Open Court, 2005.
Haugeland, J. Artificial Intelligence:The Very Idea. Cambridge, MA: MIT Press.
Cunningham, S. What Is a Mind? Indianapolis: Hackett Publishing Company, 2000.