Philosophy and Evolutionary Theory.

Philosophy of Mind and Evolutionary Theory

But I agree with Alvin Plantinga, that unlike divine benevolence, the application of evolutionary theory to the understanding of our own cognitive capacities should undermine, though it need not completely destroy, our confidence in them. Mechanisms of belief formation that have selective advantage in the everyday struggle for existence do not warrant our confidence in the construction of theoretical accounts of the world as a whole. I think the evolutionary hypothesis would imply that though our cognitive capacities could be reliable, we do not have the kind of reason to rely on them that we ordinarily take ourselves to have in using them directly-as we do in science…The evolutionary story leaves the authority of reason in a much weaker position.” (Nagel: Mind and Cosmos pp. 27-28)

In the last fifteen or so years three prominent philosophers have in different ways challenged contemporary evolutionary theory, or rather they have questioned whether evolutionary theory as it is currently conceived can explain what it purports to explain. These three theorists; Nagel, Plantinga, and Fodor[1] all have different ideas of what exactly is wrong with evolutionary theory. However in all three cases a big part of what informs their critique is the theory of mind that the theorists accept. Over the course of four blogs  I will discuss and critique Nagel and Plantinga’s arguments and demonstrate the flaws in their theories. I will then discuss Fodor’s different criticisms show where he goes wrong in his interpretation of evolutionary theory.  Finally I will trace their erroneous views on evolution to their incorrect theories on the nature of the mind. I will demonstrate that the methodological dualism which has long infected psychology is now spreading to evolutionary biology. With this in mind I will discuss the importance ridding our theory of the mind of all traces of methodological dualism. In this my first blog on the topic I will restrict myself to Nagel. My next blog will be a discussion of Plantinga.

Nagel’s critique of evolutionary theory relies heavily on an appeal to his intuitions, there are two problems with this approach; (1) people’s intuitions on various topics vary radically (See my Dennett and The Typical Mind Fallacy), (2) Nagel appeals to them in areas where we have independent evidence that the intuitions are faulty. Throughout ‘Mind and Cosmos’ he speaks about the idea of natural selection turning one species into another as being improbable. He also speaks of it being improbable that life could have emerged from non-life from purely chemical/physical processes in the time that the earth has existed. Now as I have said before if he is using improbable in a technical sense he needs to provide us with the math. Because he provides no math to support his claim I presume he isn’t using probability in a technical sense. I think that he is rather using probability in an intuitive sense. Anybody who has taken classes in probability, statistics, or in psychology will know that our intuitive sense of probability is not that reliable. So given this fact we have reason to doubt that Nagel’s intuitive sense of the improbability is an accurate guide to reality. This is the sense in which I think that his intuitions are not sufficient to cast serious doubt on Evolutionary Theory. Some of his other arguments that Evolutionary Theory cannot account for Consciousness, Cognition, Morals and Value also rely on intuitions as well so it may be worth looking closely to see if there is a reason to cast a doubt on these intuitions as well.

I have made no secret that I am not a fan of ‘Mind and Cosmos’, however if pushed I would argue that the strongest argument in the book is the argument that evolutionary theory cannot account for the emergence of Cognition. So it may be worth keying in on this argument to see what it amounts to. Nagel argues that there are two main problems concerning cognition which pose difficulties for the theory of evolution. (1) The likelihood that the process of natural selection should have generated creatures with the capacity to discover by reason the truth about a reality that extends vastly beyond initial appearances. (2) The difficulty of understanding naturalistically the faculty of reason that is the essence of these activities.

Nagel first deals with problem 1 in four pages (Mind and Cosmos p. 74-78), where he makes two citations: a paper by philosopher Sharon Street on value realism, and a book by Sober and Wilson on the evolution of unselfish behavior. Nagel concludes that it may be possible to tell a vague just so story about the evolution of reason even if the story sounds a bit implausible. This just-so story he argues will have difficulties explaining how we have evolved brains which are capable of understanding the complex mathematics used in quantum theory. Firstly I should say that Nagel is correct it is indeed difficult to construct an accurate theory of this; though I am not really sure what follows from this fact other than that science is difficult. He also mentions that explaining how language evolved is extremely difficult:

An important aspect of this explanation will be that we have acquired language and the possibility of interpersonal communication, justification, and criticism that language makes possible. But the explanation of our ability to acquire and use language in these ways presents problems of the same order, for language is one of the most important normatively governed faculties. To acquire language is in part to acquire a system of concepts that enables us to understand reality… (ibid. p. 72)

He grudgingly concedes that it is possible to tell a just-so story implausible as it may sound that explains the evolution of language and our ability to understand complex mathematics.

As I have already said Nagel is correct to point out these difficulties. However I do find his tone here extremely irritating. He speaks constantly of telling just so stories to explain this or that. This implies that evolutionary theorists are pretty much constructing ad-hoc stories some of which are not even particularly plausible. However this is a gross caricature of what evolutionary theory is all about. Anyone who was following recent debates between Chomsky-Hauser-Fitch vs Pinker-Jackendoff on the evolution of language can attest to this. Theorists are not just creating ad-hoc stories rather their theories are constrained by and can be refuted by empirical data from a variety of different sources. So, for example, when discussing the evolution of language data such as the physiology of the human vocal tract is considered, genetic data is considered, archeological facts are considered, facts from neurology and developmental psychology are considered, comparative data from other species are considered, detailed facts about the structure of the language faculty are considered as well. Theorists like, Chomsky, Pinker, Tomasello, Jackendoff etc. have all had to modify their theories about the evolution of language as we have learned more from all of the above disciplines. It should be obvious to anyone who has actually tried to understand these issues that Nagel’s talk of vague just-so stories is unfounded. Dan Dennett once criticized Nagel’s view that we could never understand what the subjective experience of a bat is by criticizing Nagel for not even trying to do so. Dennett’s point is that if you admit defeat from the outset of course you will not succeed. I think that a similar point can be made about Nagel’s views on the origins of cognition. Nagel claims that we MAY be able to tell a just-so story about the evolution of cognition, but his tone implies that even if we do it won’t have much scientific standing. I agree that the story he told in his four page consideration of the evolution of cognition is a vague just-so story, however that is because he does not consider any of the relevant scientific facts. When one bothers to look into the empirical facts a different and more interesting scientific picture emerges than Nagel is bothered to consider.

Nagel’s second difficulty with the evolution of cognition is more substantial. He notes that when we tell an evolutionary story about the origin of our reasoning capacity, we are forced by the logic of evolution to treat these reasoning capacities as fallible products of our evolutionary history. So we must admit that while our reasoning capacities are mainly reliable we cannot say that they have universal application. They were forged in the contingent conditions of the various ancestral environments so they may not be equipped to work in all environments. So, to take a clichéd example, while our intuitive logic may be useful in some domains, it is not really able to deal with the strange facts about quantum physics. However, Nagel notes that any modifications that we make to our reasoning systems because of some new discovery will itself rely on our reasoning capacities, so we will be assuming that our reasoning capacity has universal validity even in the act of critiquing it. This kind of meta-reasoning ability which applies to everything he argues is not compatible with an evolutionary explanation which would have only equipped us with reasoning which is valid for the particular environments that our ancestors evolved in.

Now there are various different responses which we can make to Nagel’s conundrum. Firstly the fact that we must use our reason to critique our reason is true and important. So, for example, when someone like Graham Priest tries to argue against the law of non-contradiction he does so by beginning with our standard logic and using this to develop a logical system which the thinks is more accurate, the same is true of Jan Brower when he argued against the law of excluded middle as a law of logic. They had to presuppose some logical system which they thought had universal validity to develop their own logical laws which the felt were more accurate than the original three laws of thought. So I think that Nagel is correct on this point. However the fact that we must presuppose that our reasoning is at some level valid when critiquing our reason is a fact about our human psychology. This shows that to some degree our thought processes are limited by the type of creatures we are. Because we are creatures created by natural selection we must admit the logical possibility that our reasoning processes are not universally valid. They seem universally valid to us because of the type of creature that we are, however we have no guarantee that actually are. And if they are this would be the result of a type of cosmic coincidence not something that was selected-for, as there is little reason to think that a universal reason would be selected.

Nagel would probably reply to this that my whole story presupposes a universal logic because I am relying on the notion of logical possibility. I would reply to Nagel, that rather I am relying on my own cognitive capacities which are generally reliable. The reliability of human cognitive capacities are shown by pragmatic success that their employment leads to in our interactions with the world on a day to day basis.

Having discussed what he considers the two main problems evolutionary theory has to explain cognition he then proceeds to discuss the nature our cognitive abilities and how they may have evolved. He makes the following point:

“In light of the remarkable character of reason, it is hard to imagine what a naturalistic explanation would look like” (Ibid p. 86)

Now we saw above that Nagel’s discussion of the evolution of language which he thinks is a key component of our thinking took him only four pages, and he considered virtually no scientific data when discussing the issue. So it is little wonder he cannot imagine a naturalistic solution, he puts virtually no effort into doing so. I cannot imagine how to build an airplane; this is because I know nothing about the engineering of the machine, not because there is some problem in principle with building an airplane. On this issue I think Nagel would be well advised considering Dennett’s advice “Don’t confuse a failure of imagination with an insight into the nature of reality”.

Again Nagel appeals to his lack of imagination to argue that a reductive account of reason is extremely unlikely. He claims that rationality is necessarily a feature of the functioning whole conscious subject (ibid: p. 86), he goes on to argue that we cannot even conceive of rationality as being composed of countless little atoms of rationality. He then baldly states that a computer cannot be rational because it lacks the necessary understanding. Such a computer could account for behavioral output but it could not account for understanding. Now given the fact that computational theory of mind has had such incredible success in modeling embodied cognition, vision, and language one would think that Nagel dedicates a few chapters at the very least to support his controversial claim. This is however not the case, rather Nagel simply dismisses the computational theory of mind in a single paragraph on p. 86. With his casual dismissal of any hope for a computational theory of mind out of the way Nagel argues that we must draw the conclusion that reason is an emergent property of the whole functioning conscious organism. Nagel then says that because a causal explanation of an emergent property is extremely difficult to imagine we may need to appeal to a teleological explanation.

Now this mode of arguing is extremely cavalier, he dismisses any hope of a computational account of rationality which gives us an excellent chance of giving a reductive evolutionary explanation in a single paragraph. He then uses this rejection of the computational theory of mind to argue that we need to appeal to a teleological principle for which there is virtually no independent evidence. Unless Nagel can provide some evidence to show why the computational theory of mind cannot work one wonders why his argument should be taken seriously.

The only reason he offers to support his claim that the computational theory of mind cannot work is the claim that computers cannot understand, though they do behave as though they have understanding. He offers no evidence to support this assertion. Presumably what he has in mind is Searle’s Chinese Room argument which purports to show that we cannot derive our semantics from our syntax. This thought experiment has been discussed ad-nauseum in the literature. While the thought experiment has some sympathizers it is far from a conclusive proof. In fact it is subject to a simple objection, the thought experiment is an intuition pump which relies on getting us to focus on the person in the room manipulating the symbols (who has no understanding of the meaning of the symbols), as opposed to the whole system where the understanding resides. Whether one accepts this systems objection, it clearly shows that the Chinese room argument doesn’t really conclusively establish anything. Rather it merely appeals to our intuitions that a machine cannot have understanding. Now such a flimsy thought experiment is hardly sufficient to show that a reductive computational account of reason is impossible, and given that Nagel’s  alternative emergent teleological position has no independent evidence to support it I see no reason why we should not continuing to work on computational models.


[1] Fodor co-authored What Darwin Got Wrong with Massimo-Piattelli-Palarimi. However I shall not consider Piattelli-Palmarini’s views here as my purpose is to discuss philosophers and their relation to evolutionary theory.

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