Monday, February 7, 2011
Putnam on causation, intentionality, and Aristotle
For the last three centuries a certain metaphysical picture suggested by Newtonian or Galilean physics has been repeatedly confused with physics itself. (More recently, metaphysical pictures suggested by biology and by computer science have been confused with those subjects themselves, in much the same way.) Philosophers who love that picture do not have very much incentive to point out the confusion – if a philosophical picture is taken to be the picture endorsed by science, then attacks on the picture will seem to be attacks on science, and few philosophers will wish to be seen as enemies of science.
I recall that, while in grad school, a fellow student and I once lamented that Hilary Putnam – who by the 1980s had abandoned the scientism and naturalistic reductionism that had characterized his early work – had gone soft philosophically. I think this was a common attitude in those days. What idiots we were. In fact Putnam had become an even more serious, nuanced – and indeed rigorous – thinker than he already had been. That is why he took the turn he did: He saw that the dogmas to which he had been committed (and to which so many contemporary academic philosophers still are committed) simply did not do justice to the facts, to the richness and complexity of the real world.
A central yet insufficiently appreciated element of Putnam’s critique of naturalism is his view that intentionality cannot be accounted for in causal terms, and that (the relevant notion of) causation itself cannot be accounted for in physicalistic terms. (This is related to, but distinct from, his well-known “model-theoretic argument” against certain versions of realism.) This is a theme that crops up over and over again in Putnam’s later work. It is most fully developed in his 1992 book Renewing Philosophy – a volume filled with interesting things, and which anyone who wants to understand contemporary analytic philosophy should read. Important relevant material is also to be found in his paper “Is the Causal Structure of the Physical Itself Something Physical?” (available in his collection Realism with a Human Face), his book The Many Faces of Realism, and his paper “Aristotle after Wittgenstein” (in his collection Words and Life).
Causal theories of intentionality try to show that a neural state or process B will represent or stand for some object, event, or process A if B is caused by A in the right sort of way. If a certain neural structure bears the right sort of causal relation to cats, for example, then it will represent cats. The trick is to spell out what the “right” sort of causal relation involves, in a way that avoids certain well-known counterexamples. (We looked at how Fred Dretske tries to accomplish this in an earlier post.) Biological or “biosemantic” theories of intentionality are essentially a Darwinian riff on the causal approach, tracing the causal chains claimed to underlie intentionality beyond our immediate environment and back to the environment in which the brains of our ancestors were shaped by natural selection.
Putnam does not think either sort of theory can work. Take the latter first. Biosemantic theories claim that a neural state or process B will represent some object, event, or process A if B was selected for because of some advantage it provided vis-à-vis A. So, consider the suggestion that a certain neural “data structure” evolved in dogs to facilitate their getting meat, and that this justifies us in attributing to them a concept or “proto-concept” of meat (Renewing Philosophy, pp. 27-33). As Putnam points out, a dog will be satisfied and nourished whether it is given fresh meat, canned meat, or some textured vegetable protein that looks, smells, and tastes exactly like meat. For that reason, there is no fact of the matter about whether its putative “proto-concept” represents any one of these in particular, and thus no sense to be made of the question of whether the dog has a true belief about what it is eating when it eats the vegetable protein rather than meat. “Evolution didn’t ‘design’ dogs’ ideas to be true or false, it designed them to be successful or unsuccessful” (Renewing Philosophy, p. 31).
But in that case, Putnam says, the suggestion that the dog really has a “proto-concept” of meat in the first place is groundless:
[T]he whole idea that a unique correspondence between the data structure and meat is involved in this bit of natural selection is an illusion, an artifact of the way we described the situation. We could just as well have said that the data structure was selected for because its action normally signals the presence of something which has a certain smell and taste and appearance and is edible. (Renewing Philosophy, p. 31)
In short, there is nothing in the situation described that entails that anything in the dog’s brain corresponds to meat specifically, and thus there is nothing in the situation that entails that the dog has a concept (or “proto-concept”) of meat. The point is completely general, applying to any concept. Natural selection favors survival value, not truth or falsity. Hence you are not going to get truth or falsity from natural selection, and neither will you get from it the concepts that thoughts and statements – the sorts of things that are susceptible of being either true or false – presuppose.
Indeed, the very idea that the evolutionary processes under discussion have anything to do with explaining the origin of intentionality in the first place is an illusion. After all, gazelles’ legs were favored by natural selection because they allowed gazelles to run fast and thereby to escape predators. But no one suggests that this shows that a gazelle’s leg has the concept of running fast, or the thought that now would be a good time to run. As Putnam writes:
Isn’t it with dogs as with gazelles? Dogs which tended to eat meat rather than vegetables when both were available produced more offspring (gazelles which ran faster than lions escaped the lions and were thus able to produce more offspring). Just as we aren’t tempted to say that gazelles have a proto-concept of running fast, so dogs don’t have a proto-concept of meat… The “reference” we get out of this bit of hypothetical natural selection will be just the reference we put in our choice of a description. Evolution won’t give you more intentionality than you pack into it. (Renewing Philosophy, pp. 32-22)
In other words, in order to make the evolution of certain neural structures relevant to the explanation of intentionality, a “biosemantics” theorist has to presuppose that such neural structures “represent” the external world in a way that the gazelle’s leg structure (say) does not; he is reading intentionality into the biological facts, not deriving it from them.
Causal theories also subtly presuppose what they are purporting to explain. Criticizing Jerry Fodor’s version of the causal theory, Putnam notes that in everyday claims about causation, we typically distinguish between “contributory causes” or “background conditions,” on the one hand, and “the cause” of an event on the other. For example, if we say that a stuck valve caused a certain pressure cooker to explode, we are treating the stuck valve differently than the way we treat (say) the lack of holes in the vessel of the pressure cooker, even though the latter also played a role in the explosion. The lack of holes we treat as a contributory cause or background condition; the stuck valve we treat as “the cause,” as being of special significance. Putnam observes:
Yet, in the physics of the explosion, the role played by the stuck valve is exactly the same as the role of [the lack of holes]: the absence of either would have permitted the steam to escape, bringing down the pressure and averting the explosion. (The Many Faces of Realism, pp. 37-38)
For in fundamental physics, at least, one usually ignores the distinction between contributory causes and “the cause”, and tries to provide a formalism which shows how all of the factors interact to produce the final result. (Renewing Philosophy, p. 50)
Though it has no unique significance to the physics of the situation, we treat the stuck valve as special, Putnam says, because of our interests. We take it that
the valve ‘should have’ let the steam escape – that is its ‘function’, what it was designed to do. On the other hand, the surface element [present where a hole might otherwise have been] was not doing anything ‘wrong’ in preventing the steam from escaping; containing the steam is the ‘function’ of the surface of which [this element] is a part. So when we ask ‘Why did the explosion take place?’, knowing what we know and having the interests we do have, our ‘explanation space’ consists of the alternatives:
(1) Explosion taking place
(2) Everything functioning as it should
What we want to know, in other words, is why 1 is what happened as opposed to 2. We are simply not interested in why 1 is what happened as opposed to such alternatives as:
(3) The surface element … is missing, and no explosion takes place. (The Many Faces of Realism, p. 38)
Now, insofar as the distinction between “the cause” and contributing or background conditions is in this way “interest-relative” and “context-sensitive,” it presupposes the existence of our powers of representation or intentionality, for
being interested in something involves, albeit in a slightly hidden way, the notion of “aboutness”, that is, the central intentional notion. To be interested in something, in this sense, you have to be able to think about it – you have to be able to refer to it, in thought or in language. (Renewing Philosophy, p. 50)
The reason this is significant is that the aim of a causal theory is to explain intentionality or representation in purely physical terms – terms that make no reference to concepts other than those recognized by physical science. Yet given their actual examples, causal theorists in fact help themselves to a “notion of things ‘causing’ other things [which] is not a notion… simply handed to us by physics” (Renewing Philosophy, p. 50) – namely, the everyday notion that presupposes the interest-relative distinction between “the cause” and contributing or background conditions. That is to say, they make reference to ordinary objects – cats, the valves on pressure cookers, and the like – in a way that gives them a causal significance they do not have in the sorts of explanations physics offers. Nor is it easy to see how these theorists can avoid doing this, given that their aim is precisely to explain how we can represent such everyday objects in thought and language. But in doing it they are subtly presupposing the existence of intentionality – the very phenomenon they are supposed to be explaining.
The bottom line, as Putnam puts it in “Is the Causal Structure of the Physical Itself Something Physical?”, is that “Nature, or ’physical reality’ in the post-Newtonian understanding of the physical, has no semantic preferences” (p. 83, emphasis mine). There is nothing in the physical facts so conceived that can determine why any particular causal chain “can be singled out as ‘the’ relation between signs and their referents” (p. 89). On the Aristotelian conception of nature championed by the medieval Scholastics, material substances and processes were inherently “directed towards” certain ends or “final causes” beyond themselves, given their “essences” or “substantial forms.” A kind of meaning was built into the material world from top to bottom. But the early modern philosophers and scientists defined themselves against this essentialist and teleological view of nature, embracing a “mechanistic” picture of the world as devoid of any inherent formal or final causes – a picture contemporary naturalists take for granted.
Yet, as Putnam argues, causal theorists of intentionality, though officially committed to the anti-Scholastic, anti-Aristotelian revolution of the early moderns, are also implicitly beholden to “a notion according to which what is normal, what is an explanation, what is a bringer-about, is all in the essence of things in themselves”; and they are thereby beholden, in effect, to “a medieval notion of causation” (p. 88, emphasis added). For the idea that there is an “intrinsic distinction” between the cause of an event and mere background conditions “has much more to do with medieval (and Aristotelian) notions of ‘efficient causation’ than with post-Newtonian ones” (The Many Faces of Realism, p. 26). It presupposes an “Aristotelian conception of form” – of “self-identifying structures” which objectively demarcate the ordinary objects of our experience from each other in a way they are not demarcated by modern physics (“Aristotle after Wittgenstein,” pp. 68-69). And if we implicitly affirm such notions in the course of giving a causal account of intentionality, “then we abandon materialism without admitting that we are abandoning it” for in that case we “project into physical systems properties… that cannot be properties of matter ‘in itself,’” at least not given the post-Newtonian conception of matter to which materialists are committed (“Causal Structure,” p. 90).
Here, and in the quote with which I began this post, Putnam might sound a bit like the author of The Last Superstition (minus the polemics and right-wing politics, anyway). Indeed, Putnam allows that the considerations he raises are “grist for the mill of a possible latter-day Aristotelian metaphysics,” and that an Aristotelian might naturally respond “I told you so. You cannot do without the notion of form” (“Aristotle after Wittgenstein,” p. 69). As I have noted many times (e.g. here), materialists constantly help themselves to concepts to which they are not entitled given their basic assumptions about the nature of matter, but which make perfect sense on a broadly Aristotelian or Scholastic set of assumptions. They don’t see this because most of them know, if anything, only caricatures of Aristotelianism and Scholasticism. Nor, given the ideological interests noted by Putnam, do they have much incentive to try to see beyond the caricatures.
Putnam, a better informed and non-ideological philosopher, does see what is going on. But he does not himself go in a neo-Aristotelian direction, opting for pragmatism instead. I’ll address his reasons in a future post. (Meanwhile, our pal Bill Vallicella has recently posted on Putnam’s argument himself. Take a look.)