Why Thoughts Cannot be Chemical Events

 

 

The usual kinds of theoretical identity exhibit a common feature: we can give a compositional analysis of the thing being identified in terms of what it is being identified with. Thus in the case of “water is H2O” we can analyze water as composed of two parts hydrogen to one part oxygen: these are the constituents of water. This is chemical compositional analysis. If water could not be analyzed in this way, it would be false to say that water is H2O. Similarly for “heat is molecular motion”: heat can be analyzed as composed of rapidly moving molecules. Likewise for “light is a stream of photons/pattern of electromagnetic waves”: light is composed of such constituents. In all these cases there is a kind of hidden structure to the thing in question and it reduces to that structure by compositional analysis. The structure may not be obvious, the constituents may be remote from common sense, but the thing in question is in fact made up of these constituents in that structure. It certainly does not have a compositional analysis that differs from that with which it is identified. The analysis is what grounds the claim of identity, so the identity cannot hold without the analysis holding. Often the analysis reveals the phenomenon to be more complex than we might have supposed; but there is no doubt that the phenomenon is to be analyzed in that way. It has turned out that water, heat, and light have such-and-such a compositional analysis. If someone tried to claim that heat is light, say, it would suffice to point out that these two phenomena have quite different sorts of composition: heat is composed of molecules in motion, light is composed of photons or electromagnetic waves. Since these are not the same, nor can heat and light be the same.

            It is the same story with other sorts of identity, such as those that apply to physiological processes. Suppose we identify digestion with a complex sequence of stages of food breakdown and absorption: “Digestion is the process that begins with food being taken into the mouth, then chewed, then swallowed, then entering the stomach, and so on.” We have analyzed digestion into its component parts and explained how those parts aid the process. That process was largely hidden, but science has revealed it, and we can now state the appropriate identity, which is underpinned by physiological compositional analysis. Similarly for breathing and gestation: we can say what breathing is by talking about the lungs and their action, oxygen and the blood, thus providing a compositional analysis; and we can say what gestation is by describing the processes of embryological development. We spell out the underlying complexity that constitutes respiration and gestation: this is what those processes are composed of. We suspect a hidden structure to something for which we have a mere label, and science tells us just what that hidden structure is. If someone were to try to claim that respiration is identical to gestation, it would suffice to point out that these two processes are composed quite differently—with the lungs involved in one case and the womb in the other.

            But now how does it work in the case of thoughts and the brain? The identity theorist claims that a thought is identical to a chemical event in the brain: my thinking that it is about to rain is identical to a batch of chemicals crossing a synaptic cleft or some such. Thoughts are identical to their chemical correlates—actual molecules moving and combining. When we observe brain chemistry we are observing thoughts: this is what thoughts have turned out to be. Science has discovered the hidden structure of thoughts, and it is the structure of chemicals in the brain. The correct compositional analysis of thoughts is in terms of chemical constituents and their interactions. The trouble with this familiar picture is that thoughts do not appear to have any such chemical compositional analysis. They do have a compositional analysis, in terms of their conceptual constituents, but this is not a chemicalanalysis: the constituents of thoughts comprise concepts of different kinds standing in the relation of predication and other logical relations, not chemicals that form compounds and travel across ion channels. So it is hard to see how the former can be identified with the latter. It is like trying to identify heat with light or respiration with gestation: wrong compositional analysis.

Suppose we had an identity theory of sentences: when someone hears a sentence in his mind this event is identical to a chemical event in his brain. The trouble with this theory is that while the sentence does have a compositional analysis, in terms of nouns, verbs, prepositions, modifiers, and so on, this structure is not the same as a structure of chemicals in the brain. We can’t map the sentence structure onto a structure of chemicals shuttling around between neurons. Consider that molecules break down into atoms and that atoms break down into protons and electrons: that is the compositional analysis of a molecular event. But nouns and verbs don’t break down into atoms and elementary particles—they don’t have any such compositional analysis. So sentences (uttering or hearing them) cannot be identified with chemical events. Chemical events may—and no doubt must—correlate with sentences and thoughts, but we can’t claim that the latter can be compositionally analyzed by reference to the former.  [1] By contrast, the standard examples of theoretical identity do involve clear instances of compositional analysis. Water consists of H2O in a way that the thought that it’s about to rain does not consist of a collection of chemical events. The structure of thought is not molecular structure.

            It is, however, very plausible to suppose that physiology reduces to chemistry. The physiological processes of the body—digestion, respiration, gestation, and so on—do consist of molecular processes. The body is composed of chemicals, and these chemicals provide a compositional analysis of all the processes that occur in the body. This is something we have discovered; it is certainly not obvious (there might have been a “vital force”). Molecules have the power, by joining and separating, and by energy exchanges, to produce the full range of physiological processes. Chemistry may not be alchemy, but it can achieve some remarkable transformations. We can take an activity of the body and dissect it into its chemical components, thereby achieving full explanation. There is no “explanatory gap” between physiology and chemistry, no “hard problem”, no “mysterious link”. The body really does have a chemical compositional analysis (that, ultimately, is how it is possible). Thus we can endorse “chemicalism” about the body. And that includes the brain: it too is an organ consisting of a collocation of molecules. Nerve transmission reduces to activities of molecules. The body really is a complicated molecular machine, a vast chemical factory, because molecules are versatile and productive things, capable of elaborate feats of construction and energy transfer. The body is composed of cells and the cells are composed of complex molecular structures—so it all comes down to chemistry. Thus it is reasonable to propound various kinds of theoretical identity with respect to physiology, which are entirely analogous to the identities propounded in physics and chemistry itself (such as the identification of the elements with atoms of varying atomic number). Given that chemistry is reducible to atomic physics, we then reach the conclusion that the body is indeed a physical thing—by no means a trivial result.

            But psychology does not reduce to chemistry—which is interesting because it surely depends on chemistry. Thoughts don’t have a chemical compositional analysis, unlike events of digestion or respiration—even though they are, in some sense, grounded in chemicals. We cannot be “chemicalists” about thoughts. We thus reach the conclusion that the mind is not the body: for the body is subject to “chemicalism” but the mind is not—therefore the mind is not the body. If the mind were the body, the mind would have a chemical compositional analysis; but as it doesn’t, it isn’t. Nevertheless, chemicals are, in some sense, the machinery of thought—what make thought possible, give it efficacy, embody it. We have given various technical-sounding names to this vital relation, none of them very illuminating: “supervenience”, “realization”, “emergence”, “grounding”, “hardware”, “substrate”, and so on. The connection is real enough—there is no thought without a chemical basis—but it is completely opaque. My aim has been to articulate one reason why thoughts cannot be chemical events. The fundamental point is the asymmetry between standard theoretical identifications and putative psychochemical identifications, in respect of compositional analysis.

            No doubt there are ways in which one might try to wriggle out of the argument, which are quite familiar. It might be claimed that thoughts really do have a chemical analysis, contrary to initial impressions, because we can assign their conceptual analysis to the appearances and insist that chemistry tells us their hidden real essence—as we can assign the superficial properties of water to their appearances to the human senses. The obvious reply to this is that the conceptual structure of thought is not just a dispensable superficial appearance but is the very essence of thought. Or we could dispense with thoughts altogether and just talk chemistry. Or we could protest that it’s all just a matter of “intuition” and hence methodologically suspect. Or we could question the whole idea of compositional analysis. What is clear is that there is a significant difference between standard scientific identities and the claim that thoughts are identical to chemical events, concerning the question of compositional analysis. The difference is at its most telling in the contrast between physiology and psychology in respect of chemistry. Physiology really is a branch of chemistry, but psychology is apparently not. Accordingly, thoughts are not physiological processes.  [2]

 

Colin McGinn 

                

  [1] If we adopt the language of thought theory, we can easily convert the argument from language to thought: given that inner sentences are not chemical events, thoughts cannot be either. Thoughts cannot have a chemical compositional analysis if the sentences that constitute them do not. 

  [2] We can claim that thoughts are biological processes in the sense that they are aspects of organisms that evolved by natural selection, but it doesn’t follow that they are physiological processes, like respiration and digestion. No physiological process in the brain can be a thought, on pain of reducing thinking to chemistry.

 

                                                            Transspeciesism

 

 

Western society has grown extremely tolerant of a large variety of what we might call “life-ways”—ways in which people desire to live, by choice or genetic destiny. Unmarried parents, interracial marriage, homosexuality, same-sex marriage, bisexuals, transsexuals, and transvestites—all are now regarded as legitimate life-ways, to be respected and protected. It is hard to think of any life-way that is now generally regarded as “deviant”—unless it is coercive or demonstrably harmful to others (pedophilia, zoophilia). So are there no more liberal social causes? Is there no group left that is wrongly shunned and deplored  (at least by intelligent people)? Are we finally fully enlightened?

I certainly find it difficult to think of any outstanding cases. But this is an alarming thought, because that is what people would have said before the recent liberations. We should always be careful before declaring complete moral clarity. Are there any unusual (statistically) life-ways that remain to be defended? Can we conceive of any that might need defending from irrational persecution? Genetic engineering offers some promising problem cases, at least in principle. Presumably no one would object to sex changes that proceed genetically rather than surgically—assuming they found sex change in principle acceptable. If a person desiring to change sexes could undergo a genetic overhaul that brought about the desired transformation, we would find this a tolerable way to implement the desire in question. But what should we say about other genetic possibilities?

Consider a person who desires to change sex and race: say, a white man who wants to become a black woman. We need not enquire into his reasons—that is not our business. What we know is that he has a deep-seated and carefully considered desire to makes the change in question. Let us suppose that there is a safe and reliable way to make the necessary physiological alterations (something about stem cells and gene splicing). We can suppose too that he has the support of his family and friends. He comes out of the procedure a much-changed man and lives happily ever after, never regretting his decision for a moment. Is there anything here we can reasonably object to? Not that I can see. He did no one any harm, he made himself happy, and he provided employment to some dedicated health professionals. It was his choice—what he really wanted.

But let’s take this a step further—let’s suppose a person wants to change species. Again, we needn’t go into the motivation for such a desire; we can assume that it is sincere and carefully considered. Suppose I deeply want to become an elephant: is that okay? We can stipulate that it is a safe and reliable procedure; we can even stipulate that it is reversible, so that I can return to being human if the elephant thing doesn’t work out for me. Imagine that the doctors can also guarantee my safety while an elephant, so I take no risks by making the change. So far as I can see, there is no good objection to my making this life choice—it is just part of my freedom to live as I see fit. So “transspeciesists” should not be hindered or deplored or persecuted or discriminated against. If a person wishes to become a monkey so that she can marry a monkey, I can see no objection of principle—once she is fully informed of the facts about what she proposes. Presumably, if a human becomes a member of another species, then the chances of mating with other members of that species are high, and I can see no reason why this should be prohibited or even disapproved of. If people decide they want to take transspecies vacations, becoming of another species for a limited time, that seems perfectly permissible—certainly, it cannot be condemned for being “unnatural” (compare transsexuals). It is just one life choice among many that can be made.

Yet I suspect that many people, otherwise quite liberal, will recoil at the idea of elective transspeciesism. They may ask what we would say if the entire human population decided they wanted to go transpeciesist? What if people decided to opt out of humanity altogether and join other species? They might keep remnants of their old human mental life, while being able to fly like a bird (as a bird). This is like the question of what to say if everyone decides to go female. The result would be human extinction obviously. That may be a pity, but I see no objection in each individual case. If Bill wants to be a shark, that’s his business. If Mary fancies life as a butterfly, that’s her choice. If Tom wants to be a bat so that he can know what it is like, that’s entirely his affair. It’s a matter of individual freedom, just like the other cases with which we are now familiar. We don’t have to deal with it as a pressing concern, because of the present lack of the requisite technology, but the future may well hold this very possibility, as genetic science progresses. If some terrible disease afflicts humans in the future, and the only way to avoid it is by changing species, then it may well seem like the natural and right thing to do. In any case, it belongs in the palette of human possibilities. Of course, forcing people to change species is wrong, but what is wrong with letting people decide their own species identity? We certainly can’t object that it is not what God intended (maybe it is just what he intended), or else we have to ban other kinds of transformative life choice. So transspeciesism should be put on the list of permissible life-ways. If I decide I want to become a female panther, say, that is my own personal business, and no one can object. Come to think of it…

 

                                               

 

 

 

Possible Minds

 

 

It is fair to say that today much of Freudian theory is not generally regarded as true (though it was believed to be true for most of the twentieth century–ardently so). Nevertheless, I think it would be accepted even by Freud’s contemporary critics (including myself) that his theory might have been true—its truth was at least an epistemic possibility. Moreover, his theory describes a metaphysical possibility: there really could be a mind that satisfies all of Freud’s basic tenets—there is a possible world in which people have Freudian minds. They don’t in the actual world, as we now think, but in a possible world people really might function in the way Freud claimed (Oedipus complex, repression, phallic symbols, jokes, slips of the tongue, etc)—he didn’t describe a metaphysical impossibility. So let us suppose we visit such a world: how should we conceive the minds of the people there?

            I mean to be speaking of what Freud called meta-psychology and also the philosophy of mind: specifically, with respect to the question of the unconscious. Freud argues that given his clinical findings, and hence the truth of his psychological theories, we are compelled to regard the unconscious as robustly real and robustly mental.  [1] For example, if we repress our memories and emotions, then the result will be an unconscious mental state—just as mental as a conscious state. This mental state will have all the characteristics of conscious mental states save their consciousness, i.e. availability to introspective knowledge. The mind will consist of two mental systems, conscious and unconscious, but both equally aspects of mind—endowed with intentionality, phenomenology, and functionality (causal and teleological). It turns out that Freud was mistaken in many of his theories of the human mind, but in the possible world we are considering his counterpart is completely right about the minds of thosepeople. Thus Freud’s argument for the psychological reality of the unconscious—its existence and nature—applies to the minds of the possible people in question. There could be such people and, if there were, they would have a vibrant and undeniably mental unconscious. The conscious mind would just be a part of their mind, and possibly a late arrival on the mental scene, with the unconscious mind established earlier in evolutionary history. Accordingly, the philosophy of mind in this world would have to recognize the full reality of the mental unconscious. It would be wrong to limit it to the conscious mind, as if that is all there is to psychology; the study of the unconscious would have a place of equal importance to the subject. This means, among other things, that the mind-body problem spans both parts of the mind; it is not specifically a problem about consciousness. Consciousness adds something extra to the picture, but the unconscious also raises difficult questions about its relation to the body. In this possible world theorists would feel the need to include the unconscious along with the conscious.

            However, this is not our world, as we now know.  [2] Still, something like Freud’s position holds: we do have an unconscious, even if it is not exactly as Freud described. Most obviously we have unconscious memories: so the general form of Freud’s position still stands. The many systematic interactions between the conscious and the unconscious encourage the idea that the unconscious is a robust mental system existing alongside the conscious and in no whit less real than it. Freudian theory makes this kind of conclusion vivid, but much the same is true under less extravagant conceptions of the unconscious. Those possible minds have an undeniably mental unconscious, so our actual minds should follow the same general principles, even if they are not quite as Freud described. We could even push this line of reasoning further by stipulating a psychology in which the reality of the unconscious is even more undeniable: in a possible world in which this psychology is realized it would be right to adopt a strongly realist attitude toward the unconscious. For example, suppose people were mainly motivated by monetary greed (surely more realistic than Freud’s sexual theory) but that they officially followed a religion that explicitly forbade such acquisitiveness; then we might expect powerful repression of all pecuniary desires with all sorts of odd side-effects. Suppose these people dreamt of nothing but making money and spending it, that they constantly told jokes about money, and that money-related neurosis was prevalent in their society. Suppose also that as children conscious acquisitiveness was natural and universal, before repression set in: all pecuniary desires and emotions are then ruthlessly suppressed, only to leak out in all manner of strange psychological phenomena. Wouldn’t we have overwhelming reason to suppose that these people have an unconscious mind brimming with thoughts of money, desire for money, and money-related emotions—that their unconscious mind is money-obsessed? They are not aware of these unconscious mental states, by hypothesis, but they exist nonetheless.

The point is that the mere fact of unconsciousness is not enough of a reason to doubt the psychological reality of the unconscious in the presence of strong circumstantial evidence for its existence. Being unconscious is not itself a count against the psychological reality of those states; it all depends on what the surrounding evidence looks like. And if there are possible minds in which the unconscious exists in full gleaming armor, so to speak, then we ought to be open to the possibility that our actual minds harbor just such a lusty and strapping unconscious. The metaphysical possibility of a full-blown unconscious mind should soften us up to the thought that we too are similarly endowed. Our own unconscious may not be as spectacular as those postulated (or it may be!), but it is the same kind of thing.  [3]

 

  [1] See his careful and well-argued paper “The Unconscious” (1915). He is well aware that he needs to argue that the contents of the unconscious are mental in nature, not merely physical or functional; he even sees the need to rebut the idea that the so-called unconscious is another locus of consciousness existing alongside the more familiar consciousness.

  [2] I haven’t argued for this here, assuming it to be widely accepted: who now believes in Freud’s theory of psychosexual development? Does anyone still think that trains are phallic symbols?

  [3] In fact, I think that we have many separate unconscious minds, each richly endowed (see “The Disunity of Unconsciousness”), but it is important to see that the unconscious is psychologically real even under more conservative views of its scope. Even ordinary memory requires us to accept a robust unconscious mental reality.

That should do it for uploading my unpublished work (for the moment). There may be some duplications when I couldn’t keep track of what was already up there. Now I don’t need to worry if I pop off tomorrow!