Is it Epistemically Possible that the Mind is Reducible to the Brain?

Might it turn out that the mind can be reduced to the brain? Are we now under an illusion of irreducibility that could be rectified in the future? The answer I want to give is yes and no. Let’s be specific: might it turn out that pain is reducible to C-fiber firing? I want to say (a) that it could not turn out that pain is reducible to C-fiber firing, as these things are now conceived, but (b) pain could turn out to be reducible to C-fiber firing if differently conceived. In effect, I think there is an ambiguity in reduction statements, a kind of scope ambiguity. It is true of pain and of C-fiber firing that the former could turn out to be reducible to the latter, but it is not true that pain could turn out to be reducible to C-fiber firing, where the two referring terms are taken as occurring within the scope of the “it could turn out” operator. That is, it could be true de re of pain and C-fiber firing that the former reduces to the latter, but not true de dicto that pain is reducible to C-fiber firing—not true of those things under those descriptions. Reducibility contexts are opaque not transparent; therefore, scope distinctions apply to them. Pain qua pain is not reducible to C-fiber firing qua C-fiber firing, but the things themselves might stand in the reducibility relation under other descriptions. In order to obtain a true de dicto reducibility statement, one would have to insert different descriptions; but the de re statement will be true under the non-reducing descriptions—even if those descriptions are not humanly accessible (i.e., if mysterianism is true). If we describe pain as “ABC” and C-fiber firing as “XYZ”, then we can get a true reduction statement of the form “ABC is reducible to XYZ”, but not by using “pain” and “C-fiber firing”.

Let me try to clarify matters. As things are, “water is reducible to H2O” is a true reduction statement (or we can assume so). But suppose we imagine a society rather like ours in which people have some pretty wacky beliefs: they think of what we would call chemical elements as little demons, and they believe that water is composed of such demons. They will then say that water is made of these demons—call them the “X-demon” and the “Y-demon”—conceived as invisible intelligent beings. And suppose that when they use these terms, they are actually referring to oxygen and hydrogen, though they don’t know this. It is then true of the referents of their terms that water reduces to those referents, but is it true that water reduces to an X-demon and a Y-demon, where these denoting terms are given narrow scope? Intuitively not, because this is the wrong way to think about the constituents of water—a kind of pre-scientific mythology. There is no reduction under those descriptions, but substituting other terms for them with the same reference yields a truth. We have reduction de re but not de dicto, though our terms (“oxygen” and “hydrogen”) also give a de dicto reduction. In other words, reductions have a conceptual component as well as an objectual component—like beliefs and other propositional attitudes. This is not surprising given that reduction is connected to explanation, which also produces intensional contexts. The same kind of thought experiment applies to heat and light: if the proposed reduction base is described in sufficiently outlandish terms, this will not yield a true reductive de dicto proposition. It is no use describing what is going on inside hot objects as (say) a collection of tiny nuns rowing boats, even if this description actually picks out molecules in motion (a “referential” use in the terminology of Donnellan); you can’t reduce heat to molecular motion under that description. You can’t have a true de dicto reductive belief if you wildly and absurdly misdescribe the reduction base. Similarly, for light and “storms of fairy dust” instead of “streams of photons”, even if the former refers de facto to the referent of the latter. Just so, if “C-fiber firing” is wildly inadequate as a concept–you will need to find a better description of the referent of this term. Under that description, there is no de dicto reduction, but under another description (possibly one of which you have no knowledge) there is such a reduction. It will never turn out that pain is reducible to C-fiber firing (de dicto), but it may well turn that that pain is reducible to PRQ, this being a better description of the referent of “C-fiber firing”. If future science starts talking about the brain with new concepts, it may be that it will produce adequate reductions both de re and de dicto; meanwhile all we have is a true de re reductive statement, viz. “It is true of C-fiber firing that it reduces pain (but not qua C-fiber firing)”. Currently, we think of the brain as consisting of “fibers” that “fire”, but these may be the brain demons of the future—there may be no such things in future brain science. The brain might indeed be totally inconceivable by us in its true objective nature (its “deep structure”). In any case, it is logically possible for pain to be both reducible to C-fiber firing and not reducible to C-fiber firing, once we articulate the scope ambiguity I have detected. I think it is quite likely that we now know a number of true psychophysical de re reductions, but have no de dicto knowledge of such reductions; and yet these reductions exist in conceptual space.[1]

[1] This position explains why we think both that the mind is obviously not reducible to the brain and that it most certainly is so reducible. It has to be reducible somehow, even though we don’t know how—and the way we now view the brain is clearly inadequate. It makes sense of our epistemic situation. The case is just like the question of whether someone who has never heard the name “Hesperus” believes Hesperus is Phosphorus: he does believe of Hesperus that it is Phosphorus, but he doesn’t believe that Hesperus is Phosphorus.

Physicalisms

The word “physicalism” covers a multitude of sins: it is vague, honorific, and deeply mysterious. What does it mean? Don’t say it means “what physicists do”—that is completely circular and uninformative. Also, physics varies from one physicist to another: whose physics do we mean? Do we mean Descartes’ physics, centering around the notions of extension and mechanism? If so, empty space is physical. Do we mean Locke’s physics, in which solidity is the key idea? Do we mean Newton’s physics, in which we have the ideas of mass, force, and acceleration (plus gravity)? Is motion the essence of the physical (matter)? Do we mean Clerk-Maxwell’s electro-magnetic physics with its fields and ethereal forces? Do we mean Einstein’s physics and its apparatus of frames of reference, speed of light, denial of absolute simultaneity, time dilation, and curved space-time? This is a good deal conceptually richer than earlier conceptions of the physical. Do we mean quantum-mechanical physics with its weird and wonderful ontology and dynamics: indeterminism, wave-particle duality, entanglement, wave-function collapse, particle dissolution? Or do we mean an energy-based physics in which solid located bits of matter are a thing of the past? Or do we go the whole hog and opt for an Eddington-style physics in which the essence of matter is consciousness (or some such), or Russellian neutral monism? Don’t say we should plump for what is in common to these various theories, because that will require us to fall back on the idea of “the physical”, for which we have no definition; and there is nothing in common between them at the level of basic theoretical concepts—they are rivals. We can’t even unify gravitation theory with quantum theory. It’s really a hotch-potch of ideas designed with different goals in mind than explaining the mind.

It won’t help to move up a level and try to define the physical in terms of the organic body, say by reference to behavior or the brain. Do we mean the behavior of Pavlov, Watson, Thorndike, or Skinner—and what is meant by “behavior”? Not inner behavior, to be sure, so we must mean physical behavior—whatever that is. And do we include volition in our concept of behavior? In addition, we don’t get reduction of the mental to the physical if behavior is not reducible to the physical, so we are still stuck with explaining “physical”. Nor is the brain any help: what theory of the brain—vitalist or mechanist, localized or holistic? What properties of the brain are allowed—informational, panpsychist, unknown? No, we need to include only the physical brain if physicalism is to be vindicated, but we have yet to define the physical. Do we mean some hypothetical future physics quite unlike our present physics? But that leaves us with no conception at all, and is consistent with a future physics that denies all of current physics. The only concrete meaning is given by specific theories, but there are many of them—so many physicalisms. We might hope to make progress by narrowing it down to some concept agreed upon by all theories—say, shape or motion. Assuming these notions are not too elastic, we at least have a well-defined theory of “physicalism”—which we may label “shapism” and “motionism”. Thus, the mind is reducible to shape or to motion or possibly to both. But who holds that view? It sounds grossly implausible without the magic of that nebulous word “physical”. What shape is pain or thought or emotion—triangular, oblong, star-shaped? And is the mind an arena of motion—thoughts and feelings zipping around like so many weightless projectiles? What speed are they going, do they ever stop moving, how much slower than the speed of light are they? Is quick thinking the same phenomenon as a ball flying through space (the width of a skull)? So, the more specific and concrete we get in trying to find a formulation of physicalism, the more balderdash we spout. There is simply no content to the idea, or a ludicrous content. No one ever claims that mind (consciousness etc.) is the same thing as shape, solidity, motion, force, acceleration, electro-magnetism, curved space, quantum jumps, muscle contractions, salivation, pecking, etc. People just have a hazy (uninformed) idea in their mind of some recondite physical stuff that the mind might reduce to, because actual physics contains nothing even remotely plausible. And if mind were really matter, wouldn’t any property of matter have the seeds of mind contained in it—mass, shape, texture, sharpness? Paradigms of the material are hardly paradigms of the mental. If mind were matter, matter would be mental in its most basic form. Hence all the shady talk of emergence and supervenience. Were early theories of matter, as pronounced by the pre-Socratics, already decent stabs at the nature of mind? If some ancient Greek had stated that mind is mud, would we say “Good try old chap, but in need of a little refinement”? Or mind is sand, or mind is pebbles, or mind is sea water (matter being fresh water). Are modern theories of matter really any better from the point of view of explaining mind? What have Newton’s three laws of motion got to do with thought and feeling? Physics proper, as opposed to some fanciful idea of it, has nothing to do with mind; its basic concepts contain no hint of the mental. You might as well be a “botanicalist” about the mind—the mind consists of peas and cabbage.[1]

[1] Physicalism today is really no more plausible as a theory of mind than physicalism of the seventeenth century; it isn’t as if the progress of physics has made it any more explanatory of the mental than it used to be. We haven’t moved the physical world closer to the mind than it seemed in the past. One would think, if physicalism were true, that the progress of physics would have revealed the physical basis of the mind, but nothing like this has happened. The physical is no closer to the mind that it was three hundred years ago (or two thousand years ago). All we have are loose correlations not explanatory connections.

Football Mania

I have been enjoying the World Cup these last couple of weeks, apart from the horrendous English accents of some of the commentators (one of whom insists on calling it the World Kep). I have been impressed by the level of skill exhibited, even by England, but especially by Congo. But what really caught my attention was the level of fascination with footballers’ torsos. Women have been drooling over the spectacle of football players taking off their shirts, which is a not uncommon occurrence; Messi and Ronaldo have come in for special admiration. Admittedly, these are fine specimens of manhood, and pretty nifty with their feet too, but it’s the abs that have got these ladies all excited. There are close-ups of those abs plus lascivious commentary—libidinal, lecherous, erotomaniac. I have no objection to this flagrant ogling of the male form; indeed, I encourage it. If the female gaze likes to linger on Messi’s stomach muscles, who am I to object? It’s all very sex-positive and lust-affirmative. It may even stimulate them to get out there and kick a ball around. But is it not somewhat inharmonious with respect to the current excoriation of the male gaze? I mean, what would the feminists (bless their stony hearts) say if there were lecherous men obsessing on-air over female abs, complete with intimate close-ups? Isn’t it a bit, like, objectifying and degrading: these people are professional athletes not sex objects! I myself admire an athletic leg no matter the gender to which it belongs (with a weakness for the female leg, may God forgive me), but I doubt this would be tolerated on national television at exorbitant length. Isn’t there a touch of hypocrisy going on here? Bit of a double standard, eh, jot of inconsistency, what? I had to laugh, but really, come on. These lovely (sorry!) lascivious ladies were not above describing the players as “sexy”, “attractive”, and “hot”—words that must on no account be used about female athletes. Or am I being too critical and logocentric? Let these smitten commentators enjoy their manly pecs and abs (why abs?) while men keep silent on such matters and chuckle inwardly.

Laws and Nature

When Newton brought all motion under a single set of laws, he changed our view of nature. Now nature was uniform, seamless, of a piece. These laws were mathematical, so nature was mathematical. The natural kind corresponding to these laws was a mathematical kind. Mass, force, and velocity were mathematical kinds, definable mathematically. But then, all moving objects had the same general real essence—masses in mathematical motion. Differences of natural kind were negligible in the light on the universal laws of motion. Nature is defined by its laws and these laws were uniform. Planets, rocks, animals, humans—all were subject to the same physical laws, mathematically formulated. All should then be covered by the same science. A certain image of physical reality was conjured by this Newtonian vision: abstract, mechanical, invariant, homogeneous, mathematical. It was an entrancing vision, laying out a format for all natural sciences. It should apply to everything that moves, including animals and people.

But the science of biology was different: organisms move differently from each other, and they differ strikingly in other ways too. The biological taxonomists had their work cut out for them. Newton was no help to them. They focused on species and their differences: how did these species originate, and what defined them? The differences were at least as important as the similarities. Darwin did not seek universal laws of animal motion, applicable to Earth and beyond; he had other fish to fry (or describe). Newton’s problems were not his. He was not blinded by mathematical science, oblivious to form and function, concentrating only on mass. This made biology into a different kind of science; more different even than psychology, which could focus on the universal laws of stimulus and response. Biology, especially zoology, was all about diversity, not uniformity. It dealt with the problem of diverse species, while Newtonian physics was about uniform matter. For physics all matter belongs to one natural kind; for biology life forms are of different natural kinds. The laws, such as they are, vary from species to species; very little unites them. The natural kind ANIMAL plays a negligible role and is hard to define. The natural kind LIVING THING is even harder to pin down and is probably not even a natural kind. There are no uniform biological laws of motion—ways that all creatures behave (move through space). In physics general laws lead to mathematical etiolation, but in biology we have concrete individuality of kinds. Newton’s vision (inherited by modern physics) is one of vast homogeneity, while Darwin’s vision is one of limitless variety, local specificity. What we call “nature” looks very different under each dispensation.[1]

[1] This paper belongs with my “Biology and Physics”.