posted below y'day but was rejected (size). entire text is very relevant/interesting to the debate. have snipped it down and posting it in 2 parts. suggest you follow link to read the rest of it.
--ravi
http://cogweb.ucla.edu/Abstracts/Fodor_on_Pinker_98.html
The Trouble with Psychological Darwinism Jerry Fodor
How the Mind Works by Steven Pinker Evolution in Mind by Henry Plotkin
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Pinker and Plotkin are reporting a minority consensus. Most cognitive scientists still work in a tradition of empiricism and associationism whose main tenets haven't changed much since Locke and Hume. The human mind is a blank slate at birth. Experience writes on the slate, and association extracts and extrapolates whatever trends there are in the record that experience leaves.
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Pinker and Plotkin, by contrast, epitomise a rationalist revival that started about forty years ago with Chomsky's work on the syntax of natural languages and that is by now sufficiently robust to offer a serious alternative to the empiricist tradition. Like Pinker and Plotkin, I think the New Rationalism is the best story about the mind that science has found to tell so far. But I think their version of that story is tendentious, indeed importantly flawed. <.> Our best scientific theory about the mind is better than empiricism; but, in all sorts of ways, it's still not very good. <.>
Pinker elaborates his version of rationalism around four basic ideas: the mind as computational system; the mind is massively modular; a lot of mental structure, including a lot of cognitive structure, is innate; a lot of mental structure, including a lot of cognitive structure, is an evolutionary adaptation - in particular, the function of a creature's nervous system is to abet the propagation of its genome (its selfish gene, as one says). <.> Both authors take for granted that psychology should be a part of biology and they are both emphatic about the need for more Darwinian thinking in cognitive science. <.> It's their Darwinism, specifically their allegiance to a 'selfish gene' account of the phylogeny of the mind, that most strikingly distinguishes Pinker and Plotkin from a number of their rationalist colleagues (and from Chomsky in particular). All this needs some looking into. I'll offer a sketch of how the four pieces of Pinker-Plotkin's version of rationalism are connected; and, by implication, of what an alternative rationalism might look like. I'm particularly interested in how much of the Pinker-Plotkin consensus turns on the stuff about selfish genes, of which I don't, in fact, believe a word.
Computation.
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Massive modularity.
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Innateness.
Rationalists are nativists by definition; and nativism is where cognitive science touches the real world. As both Pinker and Plotkin rightly emphasise, the standard view in current social science - and in what's called 'literary theory' - takes a form of Empiricism for granted: human nature is arbitrarily plastic and minds are social constructs. By contrast, the evidence from cognitive science is that a lot of what's in the modules seems to be there innately. Pinker and Plotkin both review a fair sample of this evidence, including some of the lovely experimental work on infant cognition that psychologists have done in the last couple of decades. There is also, as the linguists have been claiming for years, a lot of indirect evidence that points to much the same conclusion: all human languages appear to e structurally similar in profound and surprising ways. There may be an alternative to the nativist explanation that linguistic structure is genetically specified; but, if there is, nobody has thus far had a glimpse of it. (For a review, see Pinker's earlier book, The Language Instinct). Cultural relativism is widely held to be politically correct. So, sooner or later, political correctness and cognitive science are going to collide. Many tears will be shed and many hands will be wrung in public. Be that as it may; if there is a human nature, and it is to some interesting extent genetically determined, it is folly for humanists to ignore it. We're animals whatever else we are; and what makes an animal well and happy and sane depends a lot on what kind of animal it is. Pinker and Plotkin are both very good on this; I commend them to you. But, for present purposes, I want to examine a different aspect of their Rationalism: psychological Darwinism. Pinker and Plotkin both believe that if nativism is the right story about cognition, it follows that much of our psychology must be, in the Darwinian sense, an evolutionary adaptation; that is, it must be intelligible in light of evolutionary selection pressures that shaped it. It's the nativism that makes cognitive science politically interesting. But it's the inference from nativism to Darwinism that is currently divisive within the New Rationalist community. Pinker and Plotkin are selling an evolutionary approach to psychology that a lot of cognitive scientists (myself included) aren't buying. There are two standard arguments, both of which Pinker and Plotkin endorse, that are supposed to underwrite the inference from nativism to psychological Darwinism. The first is empirical, the second methodological. I suspect that both are wrong-headed.
The empirical argument is that, as a matter of fact, there is no way except evolutionary selection for Nature to build a complex, adaptive system. Plotkin says 'neo-Darwinian theory [is] the central theorem of all biology, including behavioural biology'; 'if behaviour is adaptive, then it must be the product of evolution.' Likewise Pinker: 'Natural selection is the only explanation we have of how complex life can evolve . . . [so] natural selection is indispensable to understanding the human mind.' One reply to this argument is to say that there is, after all, an alternative to natural selection as the source of adaptive complexity; you could get some by a miracle. But I'm not a Creationist, nor are any of my New Rationalist friends, as far as I know. Nor do we have to be, since there's another way out of the complexity argument. This is a long story, but here's the gist: it's common ground that the evolution of our behaviour was mediated by the evolution of our brains. So, what matters with regard to the question whether the mind is an adaptation is not how complex our behaviour is, but how much change you would have to make in an ape's brain to produce the cognitive structure of a human mind. And about this, exactly nothing is known. That' because nothing is known about how the structure of our minds depends on the structure of our brains. Nobody even knows which brain structures it is that our cognitive capacities depend on. Unlike our minds, our brains are, by any gross measure, very like those of apes. So it looks as though relatively small alterations of brain structure must have produced very large behavioural discontinuities in the transition from the ancestral apes to us. If that's right, then you don't have to assume that cognitive complexity is shaped by the gradual action of Darwinian selection on prehuman behavioural phenotypes. Analogies to the evolution of organic structures, though they pervade the literature of psychological Darwinism, don't actually cut much ice here. Make the giraffe's neck just a little longer and you correspondingly increase, by just a little, the animal's capacity to reach he fruit at the top of the tree. So it's plausible, to that extent, that selection stretched giraffes' necks bit by bit. But make an ape's brain just a little bigger (or denser, or more folded, or, who knows, greyer) and it's anybody's guess what happens to the creature's behavioural repertoire. Maybe the ape turns into us. Adaptationists say about the phylogeny of cognition that it's a choice between Darwin and God and they like to parade as scientifically tough-minded about which one of these you should pick. But that misstates the alternatives, so don't let yourself be bullied. In fact, we don't know what the scientifically reasonable view of the phylogeny of behaviour is; nor will we until we begin to understand how behaviour is subserved by the brain. And never mind tough-mindedness; what matters is what's true. <.>
One last point about the status of the inference from nativism to psychological Darwinism. If the mind is mostly a collection of innate modules, then pretty clearly it must have evolved gradually, under selection pressure. That's because, as I remarked above, modules contain lots of specialised information about the problem-domains that they compute in. And it really would be a miracle if all those details got into brains via a relative small, fortuitous alteration of the neurology. To put it the other way around, if adaptationism isn't true in psychology, it must be that what makes our minds so clever is something pretty general; something about their global structure. The moral is that if you aren't into psychological Darwinism, you shouldn't be into massive modularity either. Everything connects. For the sake of the argument, however, let's suppose that the mind is an adaptation after all and see where that leads. It's a point of definition that adaptations have to be for something. Pinker and Plotkin both accept the 'selfish gene' story about what biological adaptations are for. Organic structure is (mostly) in aid of the propagation of the genes. And so is brain structure inter alia. And so is cognitive structure, since how the mind works depends on how the brain does. So there's a route from Darwinism to socio-biology; and Pinker, at least, is keen to take it. (Plotkin seems a bit less so. He's content to argue that some of the notorious problems for the selfish gene theory - the phylogeny of altruism, for example - may be less decisive than one might at first suppose. I think that settling for that is very wise of him.)
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