Friday, December 1, 2017

Fodor and Piatelli Palmarini on Natural Selection

The NYT obit on Jerry Fodor accurately recognizes the important contributions he made to philosophy, psychology and linguistics. The one reservation noted, the strained reception of his late work on evolution and his critique of Darwin. It accurately notes that Jerry saw the achilles heal of natural selection theories residing in their parallels with behaviorism (a parallel, it should be noted, that Skinner himself emphasized). Jerry and Massimo concluded that to the degree the parallels with behaviorism were accurate then this was a problem for theories of natural selection (a point also made by Chomsky obliquely in his review of Skinner at the outset of the cognitive revolution). I think it is fair to say that Jerry and Massimo were hammered for this argument by all and sundry. It's is one thing to go after Skinner, quite another to aim to decapitate Darwin (though how much Darwin was a radical selectionist (the real target of Jerry's and Massimo's critique) is quite debatable). At any rate, as a personal tribute to the great man I would like to post here an outline of what I took to be the Jerry/Massimo argument. As I note at the end, it strikes me as pretty powerful, though my aim is not to defend it but to elucidate it for most of the critiques it suffered did not really engage with their claims (an indication, I suspect, that people were less interested in the argument than in defending against the conclusion).

The content of the post that follows was first published in roughly this form in Biolinguistics. I put it up here for obvious reasons. Jerry Fodor was a great philosopher. I knew him personally but not as well as many of my friends did. I was charmed the few times I socially interacted with him. He was so full of life, so iconoclastic, so funny and so generous (most of his insights he graciously attributed to his grandmother!). I looked up how often I talked about Jerry's stuff on FoL and re-reading these made me appreciate how much my own thinking largely followed his (though less funny and less incisive). So, he will be missed.

So, without further ado, here is a reprise of what I take to have been the Jerry/Massimo argument against Natural Selection accounts of evolution. 


Jerry Fodor and Massimo Piatelli-Palmarini (F&P, 2010) have recently argued (in What Darwin Got Wrong) that the theory of Natural Selection (NS) fails to explain how evolution occurs.  Their argument is not with the fact of evolution but with the common claim that NS provides a causal mechanism for this fact.  Their claim has been greeted with considerable skepticism, if not outright hostility.[1]  Despite the rhetorical heat of much of the discussion, I do not believe that critics have generally engaged the argument that F&P have actually presented.  It is clear that the validity of F&P’s argument is of interest to biolinguists.  Indeed, there has been much discussion concerning the evolution of the Faculty of Language and what this implies for the structure of Universal Grammar.  To facilitate evaluation of F&P’s proposal, the following attempts to sketch a reconstruction of their argument that, to my knowledge, has not been considered.

1. 'Select' is not 'select for', the latter being intensional.[2]    
2. The free rider problem shows that NS per se does not have the theoretical resources to distinguish between ‘select’ and ‘select for.’
3. If not, then how can NS causally explain evolutionary change?
4. There are two ways of circumventing the free rider problem.[3]
a.                    Attribute mental powers to NS, i.e. NS as Mother Nature, thereby endowing NS with intentionality and so the wherewithal to distinguish ‘select’ from ‘select for.’ 
b.                   Find within NS Law supporting counterfactuals, i.e. Laws of Natural Selection/Evolution, which also would suffice to provide the requisite intentionality.
5. The first option is clearly nuts, so NS accounts must be presupposing 4b.
6. But NS contains no laws of evolution, a fact that seems to be widely recognized!
7. So NS can't do what it purports to do; give a causal theory that explains the facts of evolution.
8. Importantly, NS fails not because causal accounts cannot be given for individual cases of evolution. They can be and routinely are. Rather the accounts are individual causal scenarios, natural histories specific to the case at hand, and there is nothing in common across the mechanisms invoked by these individual accounts besides the fact that they end with winners and losers. This is, in fact, often acknowledged.  The only relevant question then is whether NS might contain laws of NS/Evolution?  F&P argue that NS does not contain within itself such laws and that given the main lines of the theory, it is very unlikely that any could be developed.
9. Interestingly, this gap/(flaw) in NS is now often remarked in the Biology Literature.  F&P review sample some work of this sort in the book. The research they review tends to have a common form in that it explores a variety of structural constraints that were they operative would circumscribe the possible choices NS faces. However, importantly, the mechanisms proposed are exogenous to NS; they can be added to it but do not follow from it.
10. If these kinds of proposals succeed then they could be combined with NS to provide a causal theory of evolution. However, this would require giving up the claim that NS explains evolution.  Rather, at most, NS + Structural Theories together explain evolutionary change.[4]
11. But, were such accounts to develop the explanatory weight of the combined 'NS + Structural Theory' account would be carried by the added structural constraints not NS. In other words, all that is missing from NS is that part that can give it causal heft and though this could be added to NS, NS itself does not contain the resources to develop such a theory on its own.  Critics might then conclude as follows: this means that NS can give causal accounts when supplemented in the ways indicated.  However, this is quite tendentious.  It is like saying Newton's theory suffices to account for electro-magnetic effects for after all Newton's laws can be added to Maxwell's to give an account of EM phenomena!  
12. F&P make one additional point of interest to linguists.  Their review and conclusions concerning NS are not really surprising for NS replays the history of empiricist psychology, though strictly speaking, the latter was less nutty than NS for empiricists had a way of distinguishing intentional from non-intentional as minds are just the sorts of things that are inherently intentional.  In other words, though attributing mental intentional powers to NS (i.e. Mother Nature) is silly, attributing such powers to humans is not.

This is the argument.  To be honest, it strikes me as pretty powerful if correct and it does indeed look very similar to early debates between rationalist and empiricist approaches to cognition.  However, my present intention has not been to defend the argument, but to lay it out given that much of the criticism against the F&P book seems to have misconstrued what they were saying.

[1] See, for example: A misguided attack on evolution, Massimo Pigliucci. 2010. Nature 464, A misunderstanding Darwin, Ned Block and Philip Kitcher. 2010. Boston Review of Books, 35(2), Futuyma, D. 2010, Two critics without a clue. Science, 328: 692-93.
[2] Intensional contexts are ones in which extensionally identical expressions are not freely interchangeable.  Thus, if John hopes to kiss Mary and Mary is The Queen of the Night, we cannot conclude that John hopes to kiss the Queen of the Night.
[3] F&PP develop this argument in Chapter 6.  The classic locus of the problem is S.J. Gould and R.C. Lewontin.  The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist program. Proceedings of the Royal Society of London, Series B biological sciences, vol 205, 1979, 581-98.
[4] Observe, the supposition that selection is simply a function of “external” environmental factors lies behind the standard claim that NS (and NS alone) explains why evolutionary changes are generally adaptive.  Adding structural “internal” constraints to the selective mix, weakens the force of this explanation.  To the degree that the internal structural factors constrain the domain of selection, to that degree the classical explanation for the adaptive fit between organism and environment fails.


  1. I recall at the time being aggressively dumped on by about five people on some blog for merely asking for the Fodor argument to be stated. FWIW, I think the argument works well against common appeals to NS as some kinda causal agency, whereas NS proper is wholly reductionist with very local counterfactual supporting properties - NS isn't as grand as Fodor supposed. So it seems to me.

  2. I like the Mayr quote in Futuyma's comment: “Evolution seems to be a subject on which everybody thinks he is qualified to express an expert opinion” -- I always thought this of language, and it's somehow reassuring to know that specialists in at least some other fields feel this way.

    1. Select for is not part of evolutionary theory. It is a catch phrase without much meaning. This is one problem I always have with philosophers; they tend to latch onto terms too strongly. That's why there are still philosophers discussing atomism, whereas we scientists know that oxygen has 8 protons. What the theory of evolution by natural selection asserts is that the non randomness inherent in the survival and reproduction of those stable steady states we call bodies, whose states depend on parameters we call genes, ensures the non-uniform frequency of parameter values (allelic variants), which implies different distributions of body forms. A causal scenario is a set of conditions that make survival of body A more likely than survival of body B, something that can be independently verified by checking for the presence of the scenario by other means, allowing you to make statements like this one: "If there were no pollutants making the trees dark, butterflies would have stayed white". Of course you cannot make an experiment on that, but you can check that there was indeed pollution making the trees dark, that this changed the genetic composition of the population and that this did not happen with related species in areas without pollution. That looks pretty causal to me. Whether you can say that pollution selected for dark pigmentation of butterfly wings or not is irrelevant.

    2. That's why there are still philosophers discussing atomism, whereas we scientists know that oxygen has 8 protons.

      Which philosophers are you thinking of here?