Davidson’s anomalous monism

Donald Davidson’s article “Mental Events” is widely considered a classic of twentieth-century philosophy of mind, and for good reason. It contains as clever an argument for materialism as anyone has ever given. And in the course of giving it, Davidson presents, albeit in a notoriously sketchy form, a profound and important argument against the possibility of a type-type mind-brain identity theory. To use such an argument as a key component in a case for materialism – now that’s the sort of ballsiness we pay philosophers the big money for!

Like all of Davidson’s work, the article has many nuances and cannot fully be understood apart from the context of his body of writings as a whole, which more or less consisted of a great many other articles (the most important of which have now been collected in The Essential Davidson). But the basic structure of the argument is fairly simple. It goes like this:

1. At least some mental events interact causally with physical events.

2. Events related by cause and effect fall under strict laws connecting events of the kinds to which the cause and effect belong.

3. There are no strict laws on the basis of which we can predict and explain mental phenomena.

4. If some mental event M causes a physical event P, there must be some description under which M and P are related by a strict law [From 2]

5. This law can only be a physical law, not one expressed in terms of mental concepts [From 3]

6. But if M falls under a physical law, then it has a physical description.

7. And if it has such a description, then it is a physical event.

8. So (at least some) mental events are physical events.

This summary is a bit loose, but let’s suppose that it can be tightened up so as to yield a valid argument. Should we accept the premises? Certainly they seem reasonable enough, at least given the assumptions operative in most contemporary philosophy of mind. There is no glaring falsehood here; the argument is a serious one, worthy of our consideration. So what happens when we probe more deeply?

Davidson calls step 1 the Principle of Causal Interaction, and it is the least controversial premise of the argument. There have, of course, been philosophers who have denied it, but most, whether their position is materialist or dualist, would not. And they are right not to do so – at least given a certain construal of “interaction.” Let’s concede this one for now and come back to it later.

Step 3 is Davidson’s famous Principle of the Anomalism of the Mental, and constitutes the argument’s most original contribution to the philosophy of mind. It is this principle that shows, in Davidson’s view, that no type-type identity theory is possible, because such a theory requires that we can at least in principle correlate mental event types and brain event types in a law-like way. As I have said, though, his argument for the principle is notoriously sketchy. How exactly is it supposed to go?

The answer, which requires adverting to broader themes in Davidson’s philosophy of mind and language, goes something like this: Consider a “radical interpretation” scenario like Quine’s famous “gavagai” example. You’re an anthropologist attempting to translate the language of a heretofore unknown tribe. The speakers tend to utter “gavagai” in the presence of rabbits. As Quine argues, it may turn out that, depending on what metaphysical assumptions you attribute to the speakers of this language, “gavagai” could be translated as “rabbit,” or “temporal stage of a rabbit,” or “undetached rabbit part”; and three complete manuals of translation might be prepared, each of which reflects one of these possible translations and adjusts the translations of other native utterances accordingly. Now, leave aside the various ontological and semantic theses Quine illustrated with this example (indeterminacy of translation, inscrutability of reference, etc.). What Davidson is interested in is the way in which we cannot even begin to make sense of the linguistic utterances of an alien speaker of this sort without attributing to him a vast network of beliefs, desires, intentions, and other mental states. We will conclude that he means “Lo, a rabbit!” only if we assume that he conceptualizes his experiences in terms of substances (say) rather than temporal stages. Furthermore, we will conclude that that’s what he means only if we assume too that he really believes that a rabbit is present and that he intends to express that belief via this particular utterance. We will make these further assumptions, in turn, only if we also assume that his mental states are at least for the most part rational and coherent, so that he would not (for example) infer from the fact that he is seeing a rabbit that a rabbit must not be present. Even that is not the end of the story, though. For further evidence – other things the speaker says in other contexts – may lead us to revise these various judgments, so that we revise also our understanding of what he meant when he said “gavagai.” And there may be several equally plausible interpretations, each associated with its own alternative attribution of beliefs, intentions, and the like.

Now while the example is an extreme one, Davidson’s view is that something like this set of circumstances confronts us, albeit to a much less radical extent, even in ordinary linguistic contexts. Our interpretation of anyone’s linguistic behavior always involves the attribution to him of one of several possible sets of beliefs, desires, intentions, and the like, and is always revisable in light of further evidence. But by the same token – and this is the key point – our attribution of mental states to him is also always subject to the same interpretive problems. Just as we might alter our judgments about what he means in light of our assumptions about what is going on in his mind, so too might we alter our judgments about what is going on in his mind in light of our assumptions about the meaning of his linguistic and other behavior. Mind, language, and behavior are so inextricably linked that none can be understood apart from the others, and our making sense of the whole in any particular case requires attributing to a subject at least minimal adherence to standards of rationality and coherence. Otherwise we simply could not meaningfully regard what is going on with him as language and thought at all.

Now in Davidson’s view, there is as he puts it “no echo” in physical science of any of this. In understanding a physical system qua physical, we do not and need not attribute to it beliefs, desires, or any other sort of intentionality, and we do not expect it to abide by norms of rationality. Such systems are governed instead (at least on the modern “mechanistic” conception of the natural world) by patterns of brute, purposeless efficient causation. This should already make us suspicious of the very idea of a one-to-one match-up between mental state types and physical state types. The notion seems to rest on a category mistake, a failure to understand that the network of rationally-cum-semantically interrelated mental states is no more susceptible of a smooth correlation with a particular network of causally interrelated physical states than the content of a book can be smoothly correlated with a certain kind of physical format (a modern printed book, say, as opposed to a scroll, wax tablet, or electronic book). As Wilfrid Sellars might put it, the “space of reasons” and the “space of causes” are simply incommensurable.

As Jaegwon Kim suggests in his introductory text Philosophy of Mind, Davidson might accordingly be understood as arguing that if there were a law-like correlation between mental events and physical events, this would entail that what is happening in a person’s mind could be determined in a way we already know on independent grounds to be in principle impossible. In particular, it would follow that we could at least in theory “read off” a person’s thoughts directly from an inspection of his brain, without making any reference to the various alternative ways those thoughts might cohere with other thoughts or with his linguistic and other behavior. Since this is (given what was said above) something we cannot in principle do, it follows that there is no such law-like correlation between the mental and the physical. All of this suggests the following argument in defense of Davidson’s step 3:

A. The meaningful attribution of mental states to someone is governed by norms of rationality which find “no echo” in physics.

B. But if there were strict laws connecting mental events with brain events, then the attribution of mental states could proceed without reference to such norms.

C. So there are no such laws.

(None of this is inconsistent with the fact that we can often draw reliable inferences about what someone is thinking from his speech and behavior, and even from what is going on in his brain. The claim is rather that it is impossible even in principle to have a complete and, more to the point, entirely determinate understanding of his thoughts based only on knowledge of his behavior and physiology. I have addressed this issue previously here.)

All of this seems to me to be essentially correct, and it is not a small point either. (As readers of Davidson know, he bases a number of interesting philosophical theses on his analysis of the interrelationship between mind and language, including a penetrating critique of conceptual relativism.) The “anomalous” half of anomalous monism is thus well-established. What about the “monism” half? Is the mental identical with the physical, despite there being no law-like correlation between them?

My answer, which will come as no surprise to regular readers of this blog, is No, it is not. And the reason Davidson’s argument fails to show otherwise is that his conception of causation is (in my estimation) radically deficient. As I have argued elsewhere (e.g. here), the correct way to understand mental-physical “interaction” is on the model of what Aristotelians call formal causation rather than efficient causation. And one reason for thinking so is that conceiving of it on the model of efficient causation makes it hard – for materialists no less than for dualists – to avoid epiphenomenalism (as I noted here). To return, as promised, to Davison’s premise 1, then: If it is interpreted to mean (as Davidson himself did not mean it) that the mental and physical “interact” as formal and material cause, respectively, then this premise is certainly true (though in that case it cannot then be appealed to in an argument for materialism, since the Aristotelian conception of causation is incompatible with materialism). If instead it means (as Davidson intended) that they “interact” in the order of efficient causes, then though such a premise might be appealed to in support of materialism, it is false.

For the same reason, step 2 – what Davidson calls the Principle of the Nomological Character of Causality – is also in my view false. For it reflects a mechanistic view of nature, on which the material world is utterly devoid of any inherent goal-directedness or final causality and is governed instead entirely by (a stripped down version of) efficient causality. And as I have argued elsewhere (and at greatest length in The Last Superstition) this conception of nature is ultimately incoherent. By the same token, step 7 is false as well from an Aristotelian point of view. The fact that an object or event can be described in the quantitative terms typical of modern physical theory simply does not entail that such a description exhausts what is true of it. Rather, such a description is necessarily selective, abstracting away those features of the world which are irrelevant to the narrow purposes of predicting and controlling natural phenomena, but which must nevertheless be incorporated into any complete, metaphysical account of its nature.

It is only fair to note, however, that the premises in question are ones a Cartesian dualist must have a harder time dismissing, given that the Cartesian, like the materialist, is committed to a mechanistic and exclusively quantitative conception of the material world. It is no surprise, then, that Davidson should think the anomalism of the mental cold comfort to the dualist. Even here, though, the Davidsonian cannot be too smug, given that Davidson’s position only underlines the threat that epiphenomenalism poses to materialism as much as to Cartesian forms of dualism.

In any event, the fact remains that Davidson’s position, like all forms of materialism, ultimately derives whatever strength it has from the false supposition that, realistically, “there is no alternative” to materialism (or physicalism, or naturalism) if one rejects modern forms of dualism – a supposition that rests on a studied ignorance among contemporary philosophers of the true nature of the conceptual revolution by which the moderns displaced Aristotelianism (for an account of which see TLS).