Here’s a thing via A & L Daily: a Human Nature Review review, by a William D. Casebeer, of a book entitled The Evolution of Reason: Logic as a Branch of Biology, by a William S Cooper (Cambridge UP, 2001). Haven’t read the book – our library doesn’t have it - but the review nicely exemplifies rifts in the field. I am on one side, Casebeer and Cooper on the other. (I will simply take it that Casebeer is adequately representing Cooper, throughout.) What you see below is actually about three times as long as the review itself, which is a bit demented. But sometimes I do things like this. [back] Sir, the Thing Your Propose is Impossible ...(v. 2.0, foreshortened for readability) You get a bit of the flavor from the rhetorical jabs with which Casebeer opens and closes. There are, we are told, thinkers who won’t like Cooper’s attempt to reduce logic to biology. And, on the other hand, there are thinkers who have a willingness to rethink received views in light of new discoveries. Our world, apparently, is devoid of any coalition of the willing to consider and reject proposed rethinkings of received views on the grounds that they are ill-advised. Into this yawning and allegedly underpopulated metaphysical gap I propose to stride. But we’ll get back to rhetoric (nothing wrong with rhetoric.) Substance first: Cooper defends a “reducibility thesis”: logic is reducible to evolutionary theory. That is, logical rules are directly derivable from evolutionary principles. Well, which is it? Is logic reducible to evolutionary theory? Or are logical rules directly derivable from evolutionary principles. The second claim – if I understand it - is almost trivially weak. The first is exceedingly strong. But let us look more closely. As Cooper states, “according to the reductionist claim, logic is so biological that if the classical laws of logic had not already been worked out independently, an evolutionist innocent of any prior knowledge of formal logic could in principle have stumbled upon them simply by drawing out the consequences of standard evolutionary models and processes” (p. 12). Likewise, a cook innocent of any prior knowledge of formal logic could in principle have stumbled upon the classical laws of logic simply by reflecting on standard recipes and cooking procedures. (They all follow logic.) I take it this is true. Question is: what follows? Is logic fundamentally culinary? Does logic reduce, in any strong sense, to cookery? (Are logicians’ indignant refusals to identify themselves as cook’s assistants evidence of an anti-naturalistic hatred of the body?) But seriously, what am I pointing out here? No logician denies that logic is, in a sense, ‘derivable’ from any subject-matter. Just step back from the peculiar features of one’s thoughts about any given thing and you get: modus ponens, modus tollens, classical formal logic. The problem is making out how Casebeer and Cooper can possibly have convinced themselves that evolutionary biology is more than just another example of a subject-matter, like any other, to which logic applies. Reading on: Cooper supports the reducibility thesis by ascending a “ladder of reducibility”: he devotes a chapter each to showing how evolutionary theory implies life-history strategy theory; life-history strategy theory then implies decision theory; decision theory implies inductive logic; inductive logic implies deductive logic; and this in turn implies mathematics. Each of these things (descending the ladder now…) reduces back to the next (math to deductive logic a la the logicist paradigm, and so on) until you are back to life-history theory. This is a lot to do in 226 pages, so Cooper’s arguments and examples are sometimes impressionistic, as he freely admits. I confess unfamiliarity with ‘life-history strategy theory’. But I take it the term refers to strategies adopted by living organisms to ensure their histories are long, rather than short and – most important of all – that their histories become multi-volume affairs. We want our kids to have histories. So: nature red in tooth and claw and strategy. Strategies are adaptive traits. Fair enough. And clear enough how decision theory fits in. Just as nature will tend to settle on strong, sharp teeth and claws, she will tend to smile on strategies that are decision-theoretically sound. [UPDATE: The ever-watchful three-toed sloth kindly emails to fill me in on the facts of life-history strategy theory, which sounds pretty interesting, and which I sort of just mangled. The interesting strategies to study, obviously, are not the 'live long and prosper' variety (the logic there is obvious) but the 'live fast, die young breeding a million kids who will be 99.99% eaten by fish, but that's OK' variety. To put it another way, teeth and claws are tactics. As are wings that fall off if you so much as look at 'em. Strategy is what tactics aim at. So I don't know whether, as I say above 'strategies' are adaptive traits, or, rather, benchmarks for measuring the adaptivity of traits. Maybe it's a semantic difference only. Hmmm.] But this is a disaster for the Cooper thesis. Why? Well, we don’t want to reduce everything to evolutionary biology. We don’t want to reduce physics to evolutionary biology, for example. But if the likes of decision-theory (and, high above that, swaying in the trees, cheeky monkey logic) reduce to evolutionary biology, then physics does too. Why? A life-strategy is a decision-theoretic achievement. Let it be so. But sharp teeth are physical facts. If the shrewdness of a serpent’s life strategy implies that decision-theory reduces to evolution, surely the sharpness of its tooth implies that physics reduces to evolution. But that is notably absurd. What is going wrong? Casebeer and Cooper seem prepared to rest their case that logic reduces to biology squarely on the claim that evolutionary theory can predict the emergence of logical creatures, i.e. creatures that think logically or (more neutrally) behaviorally exemplify laws of logic in their life-strategies. This seems to be the most Cooper could be hoping to prove, but it is no sort of evidence – not the least hint of a suggestion of a shred of evidence whatsoever - that logic reduces to biology. Why not? Evolutionary theory also predicts the emergence of creatures that treat solid rocks as solid. Any creature that adopts a navigational strategy of walking around solid rocks will, other things being equal, tend to do better than any creature that walks straight into rocks, and keep cracking its head until it dies or starves. So evolutionary theory – plus solid rocks – implies the validity of the norm: walk around the rocks. No one would say, however, that the solidity of rocks has been biologically selected for in Darwinian fashion. How could that be? Rocks don’t have genes. But the same goes for logic. (Why not? Logical connectives don’t have genes either.) Biological entities tend to find themselves in environments in which the rocks are solid, and the laws of logic, too. If you walk into too many rocks, you die. If you die, the statement ‘you live’ is false. And since you want ‘you live’ to be true … well, you do the logic. Reduction of logic to biology (sigh). Honestly, the only reason to take this stuff seriously, so far as I can make out, is that lots and lots of people take this stuff very seriously. As Casebeer says, Cooper is riding a wave of enthusiasm for Darwinistic explanations of math and logic and that means there are lots and lots of people out there seriously confused about the philosophy of math and logic. (It’s not Darwin’s fault. He never told them to take his name in vain.) Some diagnosis, then. What is it that these folks are thinking that causes them not to see the 800-pound gorilla of a problem in the middle of the room? Here is the best I can do. Let me give two examples of bad ways to think. The first example illustrates what Casebeer (and probably Cooper) think their opponents think like. But they are wrong. The second illustrates what I think Cooper and Casebeer think like. And I am right (I think.) Case 1: the Crop Circles Farmer Brown reports that crop circles have appeared in his field. Mulder and Scully arrive on the scene. Mulder hypothesizes that an alien spaceship must have landed in the night, producing these strikingly regular geometrical patterns of flattened corn. Scully looks in the barn and finds Farmer Black – the town prankster – attempting to conceal the quite simple wooden contraption with which, to make a long story short, he made the circles. Mulder sticks to his spaceship guns, however (and starts checking Brown and Black for any alien implants they may have suffered during their close encounter.) Mulder reasons thusly: from the paltry fact that Black made the crop circles, it does not follow that a spaceship with landing gear just that shape did not land in that very spot last night. (Indeed, the aliens may lay in wait to take advantage of these sorts of opportunities.) In a sense Mulder is right, of course. The fact that Black made the circles does not prove the aliens didn’t land. But in another more accurate sense, Mulder is a complete idiot. Why? Because you don’t keep clinging for dear life to your skyhook when someone sets up a perfectly good crane to get your feet back on the good solid earth. Quite correct. I mention all this because I think Casebeer (and probably Cooper) think (very wrongly) that resistance to their favored explanations amounts to clinging to skyhooks. Refusal to accept that logic might reduce to biology is interpreted as a symptom of Platonic or transcendental yearning, of hostility to natural science. Thus, at the end of the review we get this final judgment: naturalistically inclined philosophers will find it [Cooper’s book] an enjoyable ride. Critics – by implication anti-naturalists - will not. This easy opposition omits consideration of the very real possibility – actually, a dead certainty - that naturalistically inclined philosophers will be among Cooper’s sternest critics. I should know. I am one. Another sample of rhetoric in the same vein: Those looking for a comprehensive conceptual examination of the intertwining of the normative and the empirical, with a robust a priori defense of the reducibility of the former to the latter, will be disappointed; those wishing for a more empirically informed defense of the reducibility thesis, who are willing to entertain subversive co-minglings of logical norms and biological concepts, and who aren’t so much concerned with traditional conceptual distinctions, will be intrigued by Cooper’s argument. The relevant conceptual distinction in this case is the making sense/not making sense distinction (popularized by Socrates but no doubt known even earlier.) I do not think attachment to this distinction is an instance of kneejerk traditionalism, as Casebeer rather darkly hints. I think the scientific merits of making sense, as opposed to not, can be defended, though perhaps only in rather circular fashion. But seriously, folks: Casebeer obviously has in mind the fact/norm distinction. (Logic doesn’t tell us how we do think but how we ought to think.) He obviously thinks there are folks whose knees will jerk in grim refusal to entertain any reduction of norms to facts. But this is misleading. First, lots of people do confuse facts and norms, to devastating effect, so this distinction frequently needs pointing out. It’s not the fault of the pointers-out that they are called upon to do their hygienic intellectual duty time and time again. Second, no one (I take it) takes it as axiomatic that norms cannot be reduced to facts. Anyway, fact/norm trouble in this case is at worst a mild symptom of a truly terminal, underlying condition. To return to the crop circle case, the analogous thought Casebeer and Cooper entertain is: once you have a complete, Darwinian explanation of the emergence of the logical norms of human thought, why bother believing in spooky abstract objects off in Platonic heaven? (You only posited this funny sky hook to explain something. Now the something has received a mundane explanation. Put a wrecking ball on that crane! Demolish Plato’s Heaven!) I admit that (to paraphrase Churchill on the Balkans, wasn’t it?) Plato’s Heaven manufactures more metaphysical mystery than it can consume locally. And this is a source of annoyance and disruption beyond its borders, probably. But this has nothing to do with the biological case at hand. How not? To answer a question with a question: once you have a complete, evolutionary explanation of why humans think rocks are solid, do you still need to believe rocks are solid or can you dispense with that sky hook? The answer is that you cannot dispense with it. Why not? Well, for one thing, because you are sure to have admitted ‘rocks are solid’ as a premise in your evolutionary theoretic explanation of the game-theoretic wisdom of the human life strategy of not cracking our heads against rocks. If you then go on to deny that premise, the whole evolutionary explanation comes crashing down around your mind’s ears. It is bad building practice to say: now that I have got the whole edifice up and standing solid, I can safely remove this main load-bearing item at the bottom and place it on top. No, that’s no way to play Jenga, as any 8-year old knows; and no way to do basic metaphysics either. And the same goes for logic. I’ve already said it, basically, but I say it again. Once you have a complete, evolutionary explanation of why humans reason according to modus ponens, do you still need to believe modus ponens is independently valid? Damn straight. Because how could you possibly explain the advantages of thinking this way without assuming its validity? In a world in which modus ponens did not hold, per impossibile, reasoning according to modus ponens would not confer selective advantage. (As to what it means to say that the laws of logic are objectively, non-humanly valid - yeah, it's weird, and the more so the longer you stare at it. So sue me. Or, better yet, explain it to me.) I said I had two cases, didn’t I? Right, here’s the second. Case Two: The Alien Abductions Scully has decided she is going to disprove all these reports of alien abductions once and for all. This is a very daunting task, a tough, uphill haul to a universal negative. (Compare: it is very difficult, if not impossible, to disprove Platonism.) The main obstacles, obviously, are all these folks who swear up and down they’ve been abducted by aliens. Scully needs an error theory, or theories, to cover all these cases. He was drunk, and she is just a lying publicity hound, and he saw swamp gas, then had an epileptic fit. She watches too much TV and is highly suggestible. He saw a fire engine climbing a distant hill then had a funny dream that night. That one was actually kidnapped by a yeti, and the trauma resulted in confused memories; whereas this one was a sad victim of el chupacabra. (Those are not implants but bite marks, you see.) So it goes. Every false belief in alien abductions must find its legitimate explanation. Now suppose Scully adopts the following convenient hypothesis. Many people have been abducted by aliens and subjected to mystery processes that delude them into believing they have been abducted by aliens. At first Mulder objects that this does not even seem coherent as a claim. But it is. Scully explains that it is her idea that tall grays snatch people and delude them into thinking they were snatched by short greens, whereas the short green snatchers plant memories of tall grays. Yes, that is possible. But even so – Mulder is sure to point out - this is obviously the worst possible strategy for purposes of disproving alien abductions. You cannot reduce abductions to non-abduction events if your reductive explanation expressly posits abductions. Makes no sense. Quite right. Yet Cooper and Casebeer reason analogously. How so? Well, if reducing logic to biology means anything, it means that logic is just biology, nothing above and beyond. But obviously the biological environments we are positing are governed by the laws of logic. For example, species that go extinct do not also not go extinct. If Cooper and Casebeer are not willing to assume stuff like that, they are obviously going nowhere fast. So they are assuming objective, biologically-external logic by way of reducing logic to biology. It is as flagrant an inconsistency as assuming the existence of aliens in order to disprove their existence (except as a reductio ad absurdum, which this is not.) But how exactly does their hypothesis about the evolution of logical thought map onto my alien abduction case? In each case, there is a sort of veridical fit, yet an odd epistemic gap. The abductees believe, correctly, that they have been abducted. But their belief does not – as one might have supposed – causally derive from their abductors. Rather, it derives from some unspecified intermediate operation that has taken place. Likewise with humans and logic. We believe, correctly, that modus ponens is a valid logical law. But this belief has not been read off some Platonic Ding an sich – modus ponens itself, in the Platonic flesh. Rather, the belief derives from some unspecified intermediate operation that has taken place: the evolution of our species. Nothing that looks like an alien abductor directly gives the abductees their belief in alien abductors. And nothing that looks like modus ponens gives us our belief in modus ponens. But, obviously, we can grant all this without being reductionists about logic. In fact, we cannot grant all this and be reductionists about logic. To reduce biology to logic would require imagining a world with non-logical biological entities in a non-logical environment, then logically proving – without using logic – how logic not-logically but logically emerges from non-logical biologic. To conclude: it isn’t so much a case of sawing off the limb you are sitting on as it is a case of sawing off the limb, but first cutting down the whole tree, but first clear-cutting the forest, but first for good measure driving all trees extinct, but first killing all the plants, but first blotting out the sun. But first blowing up the universe. Then trying to sit comfortably way out on that tree limb. I submit the attempt will not be an empirical success. And the funniest thing is: there is nothing whatsoever wrong with trying to give an evolutionary explanation of how creatures such as ourselves evolve the capacity to use logic. Fascinating problem. Probably Cooper has very interesting things to say about along the way. (Maybe along the lines of this recent piece in "Nature".) He just isn't reducing logic to biology, that's all.