Monday, April 30, 2012
Reading Rosenberg, Part X
And now we reach, at long last, the end of our detailed critical look at Alex Rosenberg’s The Atheist’s Guide to Reality. In this final post I want to examine what Rosenberg has to say about a set of philosophical arguments he regards as “among the last serious challenges to scientism” (p. 228). The arguments in question all entail that the realm of conscious experience -- what common sense says we know only “from inside” (p. 238), from a point of view “somewhere behind the eyes” (p. 222) -- cannot be accounted for in terms of neuroscience or physical science more generally. In his treatment of these arguments, we get Rosenberg simultaneously at his best and at his worst.
Rosenberg takes the sort of argument in question to get its “neatest force” from the example presented by Thomas Nagel is his famous article “What is it like to be a bat?” Bats get around via echolocation. What is it like to experience the world that way, as opposed to (say) visually? You might think it’s like looking at the sonar screen on a submarine, but as Rosenberg says, to imagine that is instead merely to imagine “what it would be like to be a human inside the head of a bat, using sonar screens to convert the acoustical data the bat receives into human visual experiences” (p. 230). Nor could any amount of neuroscience give us knowledge of what it’s like to be a bat. The most neuroscience can do is pile up descriptions of the arrangements of neurons, their firing patterns, and so forth. And what an echolocational experience is like is something you’ll never learn from that sort of thing. But by the same token, what it is like for a human being to have a visual experience of red (say) is also something you could never know from neuroscience alone. Hence we have, Nagel argued, no idea how conscious experience could be explained in neuroscientific terms.
Rosenberg also makes reference to some famous dualist arguments associated with Descartes and Leibniz. Descartes argued that while one cannot possibly fail to exist as long as one is even wondering whether one exists -- since to doubt this would itself be a kind of thinking, and one couldn’t do such thinking in the first place if one did not exist -- it is possible at least in principle that the entire material world, including one’s own body and brain, could be a hallucination. Hence if I could exist as a thinking thing even if my body and brain and the rest of the material world did not, I must not be identical to anything material. Leibniz argued that if we imagined some purportedly thinking, feeling, and perceiving machine expanded to the size of a mill so that we could walk around in it, we would never observe in it anything which might explain such mental activity, but only physical parts mechanically working upon each other. The same thing can be said of the brain. As Rosenberg writes:
[A]ll we would ever find are sodium and potassium molecules moving one way or the other, complex neurotransmitter molecules changing molecular shape as other molecules come into contact with them. We would never find anything that introspection identifies as an experience, a sensation, a feeling, or even a thought about stuff. We would never find anything that reveals what it’s like to have a sensation of yellow, an experience of pain, a smell or sound, or any other experience. (p. 234)
(I have discussed Descartes’ and Leibniz’s arguments at some length in earlier posts, here and here.)
Though he does not for a moment agree with any of them, Rosenberg is not dismissive of these arguments. He regards them as “wonderful, entertaining, thought-provoking riddles” (p. 228). Descartes’ argument, he says, at least “looks absolutely airtight” (p. 226, emphasis added). And Nagel’s argument is “really cool… the sort of puzzle any philosopher would give his soul to have invented, if he had a soul” (p. 233). And this reflects a strength of Rosenberg’s book that I have emphasized before: Despite the utter bizarreness of some of his conclusions -- conclusions most of his fellow atheists would not agree with -- Rosenberg has a better grasp of the philosophical implications of scientism than most of these other atheists do, and realizes that the objections to scientism cannot be as easily dismissed as some of them would like to think. Indeed, that is why his conclusions are so bizarre and extreme. Rosenberg sees that a consistent scientism requires a radical abandonment of commonsense notions of meaning, the self, introspection, and the like.
As I have said, though, his treatment of these arguments shows Rosenberg at his worst as well as at his best. The reason is that his response to the arguments amounts to little more than the combination of ad hominem remarks, begged questions, non sequiturs, etc., that one finds elsewhere in the book. However clever he acknowledges them to be, Rosenberg insists that such arguments ultimately amount to “grasping at… straws,” often by those who are “credulous about religion” (p. 227); and he assures us that Leibniz’s “theological beliefs made him particularly eager to find arguments against scientism just when it was beginning to pick up speed with Newton’s work” (p. 233). (Never mind that Nagel is an atheist, indeed someone who in his book The Last Word acknowledged that he “want[s] atheism to be true.” And never mind that other prominent contemporary philosophers who have presented similar arguments -- such as David Chalmers and John Searle -- are also atheists.)
As to Rosenberg’s actual grounds for rejecting the arguments, they lay in part in his claim that neuroscience (and, in particular, research on “blindsight” phenomena and the like) has shown introspection to be unreliable. But we’ve already seen that neuroscience has shown no such thing. Rosenberg also thinks the case for scientism is so powerful that any arguments against it can safely be rejected, even if we can’t say what is wrong with them:
Does scientism actually have to take Descartes’s argument and others like it seriously? Does it actually have to diagnose each of their mistakes, or any of them? No. Even before you hear them, science provides a compelling reason that they must all be wrong. One has only to weigh the evidence for scientism -- 500 years of scientific progress -- and the evidence against it -- including those cute conundrums. It’s clear which side has the weightier evidence. (p. 227)
Scientism is safe to conclude that there are flaws in Nagel’s argument and Leibniz’s. We don’t know where the slips occur. But we know that their conclusions are false. (p. 235)
But we’ve also already seen that, far from being strong enough preemptively to disable all counterarguments, Rosenberg’s argument for scientism is in fact embarrassingly feeble. So far, then, Rosenberg has given us no new reasons (let alone good reasons) for doubting that the arguments of Nagel et al. constitute a refutation of scientism.
But Rosenberg makes two further claims, and they deserve closer scrutiny. Here’s the first:
[T]he arguments against the mind’s being the brain cheat. They stack the deck against neuroscience so that it cannot succeed in meeting their challenge. The arguments demand that neuroscience take conscious introspection seriously. But they subtly deny it the use of any tools to do so. Naturally, if science cannot apply any of its methods to understand introspection, scientism won’t be able to show what is wrong with the arguments. (p. 229)
This, it seems to me, is quite bizarre. Suppose a critic of Gödel's incompleteness theorems complained:
Gödel's arguments cheat. They stack the deck against those who think that every true arithmetical statement in a formal system capable of expressing arithmetic is in fact provable within the system, and that the consistency of arithmetic can in fact be proved from within arithmetic itself. For Gödel's arguments do not allow their critics to use the tools of formal systems to prove these things. Naturally, if Gödel's critics cannot apply these methods, they will not be able to show what is wrong with the arguments.
Or suppose you knew someone who insisted that all money is made out of paper, and you pointed out that coins are made out of metal, that in some cultures seashells or stones have been used as money, and so forth. And suppose he complained:
Your argument cheats. It stacks the deck against me so that I cannot succeed in meeting its challenge. Your argument demands that I take coins, seashell money, etc. seriously. But it subtly denies me the use of any tools to do so. Naturally, if I can’t appeal to the paper composition of coins, seashell money, etc., then I will not be able to show what is wrong with your argument.
It is obvious what is wrong with these objections. The whole point of noting that there are such things as metal coins, seashell currency, etc. was precisely to show that not all money does have a “paper composition” in the first place. Hence to complain that noting that some money isn’t made of paper “cheats” either completely misses the point, or begs the question (if it simply assumes that all money must have a “paper composition”), or is perhaps simply a bit of childish whining. (“No fair! You’re example shows I’m wrong!”) Similarly, the whole point of Gödel's theorems is to show that the formal methods in question cannot prove what the critic thinks they can. Hence to complain that the theorems “cheat” would be entirely to miss the point, or to beg the question, or to indulge in a bit of whining.
It is hard to see how Rosenberg’s accusation is any better. He complains that arguments like Nagel’s, Leibniz’s, etc. don’t allow for the possibility that neuroscience might explain conscious experience. But showing that it is not possible for neuroscience to do so is the whole point of such arguments. You might think they fail to show this, but accusing them of “cheating” simply misses the point. Or does Rosenberg mean to insist that anything that is a genuine and not merely illusory aspect of conscious experience simply must be susceptible of a neuroscientific explanation? In that case he is just begging the question against Nagel and Co. Or is he simply whining that Nagel and Co. have come with an objection he doesn’t have a good answer to? (“If Nagel and Co. were right, scientism would be refuted! All those religious fanatics would have a good laugh at the expense of us rational, reality-based folks! And that’s just not fair!”)
Surely Rosenberg has something better than this to offer? He does, but only slightly better. It is what many advocates of scientism seem to think is their trump card, certain to guarantee victory when confronted with an objection to which they have no other answer. Here it is: “Science has managed to dispose of all the other arguments that have been advanced to show its limits” (p. 228). Therefore, it’s just a matter of time before it disposes of arguments like Nagel’s. How likely is it, after all, that the human mind, this tiny little corner of the universe, should magically turn out to be the one holdout to the centuries-long string of scientific successes?
Now, isn’t that a pretty good argument? No, it is not a pretty good argument. It’s actually a pretty bad argument, for reasons I’ve explained before -- in earlier posts (such as this one) and in chapter 3 of Philosophy of Mind and chapter 6 of The Last Superstition. To see why, consider the following analogy. Suppose the floor of the house is filthy and mom tells you to get rid of the dirt. You get out the broom and start sweeping the living room. After gathering all the dirt into a little pile, you sweep it under the rug which lies under the living room coffee table. Then you go to one of the bedrooms, sweep all the dirt in it into a pile, and sweep that pile too under the living room rug. You repeat this process for each room, for the kitchen, hallways, etc. The house was so filthy that you’ve now got a noticeable bump in the rug made by all the dirt you’ve piled under it. Your brother says: “Nice work, Einstein, but mom said to get rid of the dirt and all you’ve done is relocated it. How are you going to get rid of that lump?” You answer: “Isn’t it obvious? The same way I got rid of all the other dirt! The ‘sweep it under the rug’ method has worked everywhere else in the house. How likely is it that this pile of dirt under the rug should magically turn out to be the one holdout?” But of course, the lump under the rug is in fact the one pile of dirt that cannot possibly be dealt with the same way. There is nothing at all “magical” about this; it is simply entailed by the nature of the method. The “sweep it under the rug” method gets rid of dirt precisely by putting it under the rug. Hence you are in principle not going to be able to get dirt out from under the rug in that way. (And if your brother points this out to you, naturally it would be quite silly to accuse him of “cheating” by not letting you use your favored method to solve the problem!)
As I noted in an earlier post in this series, to say that “science has now explained everything else, and so it’s only a matter of time before it explains X (where X = qualia, or intentionality, or some other feature which poses a difficulty for naturalism)” is delusional in just the way that your thinking that the “sweep it under the rug” method would work to eliminate the dirt under the rug would be delusional. Here’s how the delusion works. First, “science” is (implicitly if not explicitly) defined in such a way that no explanation that makes reference to irreducibly teleological or qualitative features of the world is allowed to count as “scientific.” Second, seemingly irreducibly teleological and qualitative features of the world -- apparently goal-directed natural processes, say, or colors, sounds, heat, cold, and the like as these manifest themselves to ordinary experience -- are re-described as mere projections of the mind onto external reality and not allowed to count as truly “material.” Teleology, color, sound, heat, and cold as we experience them do not (so the story goes) really exist in the material world itself, but only in our subjective mental representations of it; objectively there are only colorless, soundless, purposeless particles in motion, which by virtue of their motions cause us to experience them as if they had the characteristics common sense attributes to them. (Color, sound, etc. as physical properties are accordingly also re-defined, in terms of surface reflectance properties, compression waves, and the like.) Third, it then asserted that “science has explained” such-and-such external material phenomena in a way that makes no reference to irreducible teleological or qualitative features. What is not acknowledged is that this claim is a tautology, since (again) nothing that made reference to such features would be allowed to count as “scientific,” and (again) no features that couldn’t be described in non-teleological and non-qualitative terms would be allowed to count as “material.” Fourth, it is fallaciously inferred that since this methodological sleight of hand has “shown” that irreducibly teleological and qualitative features do not exist in the external material world, we have every reason to believe that it will also “show” that they do not exist in the mind either. In particular, it is claimed that mental phenomena like intentionality (the “aboutness” or “directedness” of thought, which is comparable to the “directedness” of teleological phenomena) and qualia (which are what is left of qualitative features like color, sound, warmth, coolness, etc. when they are removed from the external world and relocated into the mind) will be “explained” in the same way that all other phenomena possessed of qualitative features or “directedness” have been explained. But in fact the mind is the one place to which the method cannot possibly be applied, precisely because the mind is the “rug” under which everything that does not fit the method has been “swept.”
Indeed, this was, more or less, the point Nagel was making in his famous article. His point was not just that the experiences of bats are so unusual that neuroscientific inquiry is not likely to tell us what it’s like to have them. The argument goes much deeper than that. Nagel’s point was that the very nature of the practice of giving a reductionist account of a phenomenon seems to preclude its application to the realm of conscious experience. For a reductionist account is couched in entirely “objective” terms, that is, terms that make no essential reference to the point of view of a particular observer. For instance, the way red looks or the way heat feels, since those are tied to the points of view of particular observers, are stripped away and relegated to the “subjective” realm of conscious experience. A reductionist account of color might define it instead in terms of the surface reflectance properties of objects, and a reductionist account of temperature might define it in terms of molecular motion -- features which are “objective” in the relevant sense. But when it comes to explaining the “subjective” point of view of the observer himself, and in particular the conscious look of red or conscious feel of heat themselves, it is hard to see how the same procedure could possibly be applied. For to strip away the subjective element in this case would just be to ignore that which is to be explained, and thus not explain it at all. As Nagel puts it: “If the subjective character of experience is fully comprehensible only from one point of view, then any shift to greater objectivity—that is, less attachment to a specific viewpoint—does not take us nearer to the real nature of the phenomenon: it takes us farther away from it.”
Nagel himself did not go so far as to say that this showed that a physicalist reduction of mental states to physical states is false, but he did think it showed that we do not have any conception of how it could be true. Other writers have drawn the stronger conclusion. For early modern thinkers like Malebranche and Cudworth, and contemporary thinkers like Richard Swinburne, it is precisely because modern science has removed color, odor, sound, taste, etc., as common sense understands them, from matter -- including the matter that makes up the brain -- and relocated them into the mind, that we should conclude that these mental features are not material. As Swinburne writes in The Evolution of the Soul:
All ‘reduction’ of one science to another dealing with apparently very disparate properties has been achieved by this device of denying that the apparent properties (i.e. the ‘secondary qualities’ of colour, heat, sound, taste, etc.) with which one science dealt belonged to the physical world at all. It siphoned them off to the world of the mental. But then, when you come to face the problem of the sensations themselves, you cannot do this. If you are to explain the sensations themselves, you cannot distinguish between them and their underlying causes and only explain the latter. In fact the enormous success of science in producing an integrated physico-chemistry has been achieved at the expense of separating off from the physical world colours, smells, and tastes, and regarding them as purely private sensory phenomena. The very success of science in achieving its vast integrations in physics and chemistry is the very thing which has made apparently impossible any final success in integrating the world of the mind and the world of physics. (p. 191)
Thus, dualism of the post-Cartesian sort is not some desperate attempt to resist the implications of the modern science; on the contrary, it follows from the conception of matter that is operative in modern science. Or at the very least, precisely by relocating whatever does not fit the reductionist approach to the “subjective” realm of the mind -- to the realm we know “from inside,” from “somewhere behind the eyes” -- modern science made that realm more problematic for the materialist, not less. That is what Nagel’s argument implies, and Rosenberg completely misses the point.
But as we’ve now seen over the course of ten posts, missing the point, begging the question, non sequiturs and ad hominems are standard fare in The Atheist’s Guide to Reality. For all that, the book is more philosophically substantive and consistent in its scientism than the atheist tomes of Dawkins, Dennett, Harris, and Hitchens. That is why it has merited our attention. If you are beholden to scientism, you ought to read Rosenberg to see how extreme and bizarre are its true implications. And how weak are some of the arguments given in its defense, even when presented by a major philosopher of science.