thinking makes it so

There is grandeur in this view of life…

Smear campaign

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Jerry Fodor

Jerry Fodor

I was delighted when my son gave me a copy of Jerry Fodor and Massimo Piattelli-Palmarini’s What Darwin Got Wrong for my birthday. Not because I did think Darwin got anything significantly wrong but because I didn’t. I like having my opinions and beliefs tested. I had heard of Jerry Fodor but not Massimo Piattelli-Palmarini (not a name one is likely to forget).

[First in a series on Jerry Fodor and Massimo Piattelli-Palmarini’s What Darwin Got Wrong.]

I read the book through once and then a lot of it a second time. I really struggled to make head or tail of their arguments, and why they thought they had such a killer critique of the theory of natural selection.

At risk of misrepresenting the book, their attack seems to be organised on three overall fronts:

(i) The theory of natural selection in biology is structurally analogous to the operant conditioning theory of learning in psychology. The theory of operant conditioning is deeply flawed. Therefore the theory of natural selection is deeply flawed.

(ii) Natural selection by definition operates exogenously. But there are many examples of evolutionary change operating endogenously. Therefore natural selection is nowhere near as significant an agent of evolution as people think.

(iii) The theory of natural selection is itself ‘fatally flawed’, as it is based on an ‘intensional fallacy’.

The writing style is energetic to the point of hectoring. Fodor and Piattelli-Palmarini (F&P-P from now on) fight their corner in every sentence.

Massimo Piattelli-Palmarini

Massimo Piattelli-Palmarini

They present themselves as fully paid-up secular humanists, believing in evolution and the genealogy of species. It is only natural selection (‘NS’) that they object to. They are therefore keen to distance themselves from creationists and intelligent design merchants:

…what people who do not like Darwinism have mostly objected to is the implication that there’s a baboon in their family tree; more precisely, they do not admit to a (recent) ancestor that they and the baboon have in common. Accordingly the question doesn’t arise for them how the ancestral ape evolved into us on the one hand and baboons on the other. This book is anti-Darwinist, but … it is not that kind of anti-Darwinist. It is quite prepared to swallow whole both the baboon and the ancestral ape, but not the thesis that NS is the mechanism of speciation.

Sorry to be picky, but it might have helped if they had taken more care to demonstrate their understanding of evolution. Baboons are Old World monkeys. An evolutionist would certainly claim that humans and baboons had a common ancestor but it would not have been an ape.

I don’t want to spend much time on (i) the analogy F&P-P see between natural selection and operant conditioning, or on any of the arguments against natural selection which they base on that analogy. It is they who see the analogy, but the reader has no independent obligation to subscribe to it, or be convinced that any argument against operant conditioning is de facto an argument against natural selection. As an attempt to establish of guilt by association it seems little more than a smokescreen.

I also do not want to spend too much time on (ii), the exogenous/endogenous debate. As I read one supposed counter-example after another I found myself wondering if I had misunderstood all the books on evolution I had absorbed over the years. F&P-P’s picture of what evolutionists typically think seemed very much at odds with what I thought they thought.

For example, take Chapter 2, Internal constraints: what the new biology tells us:

Strict neo-Darwinists are, of course, environmentalists by definition: the genotype generates candidate phenotypes more or less at random; the environment filters for traits that are fitness enhancing. But there are signs of a deep revisionism emerging in current evolutionary theory: modern biology urges us to conclude (what Darwin himself had acknowledged) that the effect of ecological variables on phenotypes is not the whole story about evolution…

This seems a bit twisted. It’s the genotype which varies more or less at random, but the genotype generates phenotypes by largely non-random processes. Some of the resultant phenotypes survive better than others and have more surviving offspring. In some cases this could be described as the environment ‘filter[ing] for traits that are fitness enhancing’ or ‘the effect of ecological variables on phenotypes’, but not necessarily or universally.

To take a random example, a mutation could result in the creation of a new digestive enzyme or a change in an existing one, which in turn results in more efficient utilisation of food, which in turn enhances the survival of individuals possessing that mutation. Is this an example of the environment filtering a fitness-enhancing trait? Only at a stretch. It isn’t really the environment (ie the nearby world outside the individual) which is causing the individual to survive better, but the efficiency improvement inside the individual itself. But in a sense the environment will probably be supplying external causes of death, so (other things being equal) the individual with the more efficient digestion might run faster than the one with the less efficient digestion and therefore be the one to escape a predator – assuming this is how the individual meets its death.

The point I am trying to make is that ‘natural selection’ doesn’t mean only ‘selection by external nature’. It means something more like ‘differential survival by natural rather than artificial means’.

But for F&P-P this differential survival resulting from differences in digestion efficiency would presumably count as one of their

internal filters on the phenotypes on which exogenous selection acts. They challenge the classical neo-Darwinist view that the course of evolution is exhaustively driven by exogenous factors.

Later they talk of the

traditional assumption that mutations have a fixed probability of occurring anywhere at random in the genome of any species…

and adduce counter-evidence about ‘hotspots’, ‘hypermutable’ regions in genomes, and ‘alternative splicing’. But which ‘classical neo-Darwinists’ make this ‘traditional assumption’? And how does any of this threaten the overall principle of natural selection?

Fibonacci spiral

Fibonacci spiral

Another line of argument is adopted in Chapter 5, The return of the laws of form. This is that there are structural features of organisms which are not accounted for by natural selection:

When very similar specific morphologies (Fibonacci series and Fibonacci spirals) are observed in spiral nebulae, in the geometrical arrangement of magnetically charged droplets in a liquid surface, in seashells, in the alternation of leaves on the stalks of plant stems and in the disposition of seeds in a sunflower, it can hardly be that natural selection is responsible. … [T]here is seemingly a simple ‘rule’, which is to place [eg] the new bud as far away as possible from the inhibitory hormone effects of the apex and of the last placed buds. … The simple ‘rule’ is not, as such, dictated by the genes – it is … the result of the laws of physics and chemistry creating constraints on possible biological forms, more particularly on stable and reproducible forms.

How this counts as evidence against natural selection baffles me. The theory of natural selection has never as far as I know claimed that every feature of an organism is the causal result of natural selection. Natural selection is the reason why some organisms have survived and not others. For example – as far as I know – no living organism exists wholly in the gaseous state. But it would be an eccentric biologist who would claim that this is because non-gaseousness has been selected for, and that therefore natural selection has caused organisms to be non-gaseous. Again – as far as I know – there is no living organism which exists wholly in the liquid state. It would be odd if it did, as it would be hard to locate the boundary of the organism. But I doubt if any biologist, even a strict or classical neo-Darwinist, would claim that natural selection caused this feature.

These are tuppenny arguments though compared to the big one: F&P-P’s claim (iii) that the theory of natural selection is based on an ‘intensional fallacy’ and is therefore ‘fatally flawed’.

For next time!

© Chris Lawrence 2011.

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7 Responses

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  1. It has long seemed to me that the weakness of Darwin’s theory is its failure in relation to prediction. It can explain almost any form of life which has evolved in the past, but is no better than a child in predicting what will evolve in response to various environmental changes which have not yet occurred.

    And scientists are rightly suspicious of theories that can explain everything. “God” is the example par excellence of the infinitely expandable explanation. But these kinds of explanations are not limited to the supernatural. Ptolemaic geocentrism in which earth was assumed to be the center around which the heavens revolved became increasingly complex and fewer and fewer people could understand it. Some people thought that its very complexity suggested that it was a very learned theory and must be right.

    Yet failures of prediction, as opposed to explanation, are endemic in science for almost all theories in every field beyond physics. But there is no other natural theory (as opposed to supernatural explanations) that comes close to explaining the diversity of living organisms as broadly and coherently as Darwin’s theory. My own inclination is that the theory is more apt to be incomplete than wrong.

    Terry Sissons

    19 July 2011 at 12:27 pm

    • Thanks Terry.

      An interesting question would be what would count as a ‘prediction’ in the case of evolutionary theory. It may be a tall order to predict what will evolve in response to environmental changes which have not yet occurred. But evolutionary biologists make predictions all the time about what they might discover where. ‘Where’ could refer to (say) a geological stratum or it could refer to a newly discovered island sufficiently cut off from any mainland for a sufficiently long time for its fauna to have evolved into familiar ‘island’ patterns.

      JBS Haldane was once asked what would constitute evidence against evolution. His reply was “Fossil rabbits in the Precambrian.” That would be an example of a familiar kind of negative prediction.

      Some at least of the huge amount of evidence amassed by Richard Lenski’s Experimental Evolution project can probably also be interpreted in terms of the verification or falsification of predictions.

      But you are right. The domains of biology and (say) physics are very different. It may have something to do with biology being about populations while physics can be about ‘essences’. Two drops of water can be instances of the same thing in a way that two monkeys can never be.

      Thanks again, Chris.

      Chris Lawrence

      19 July 2011 at 7:41 pm

      • Thank you for such an informative reply about the problem of prediction. Actually, I think what you call negative prediction is a pretty solid kind of evidence and should not be dismissed. I’m embarrassed to say I hadn’t thought of it. I’m wondering now about a similar possibility in psychology. In some cases it would be possible – in relation to Piaget’s theory of cognitive development it would. But it seems to me the more complex the system one is studying, the more wiggle room there is to explain whatever one finds in terms of ones preferred theory. As you say, even two monkeys are not identical. Maybe even two amoeba are different?

        In terms of future prediction, you say it could be a tall order to predict what will evolve in response to environmental changes which haven’t occurred yet. But I think it would quite feasible to vary environmental variables in laboratory conditions, especially for simple organisms. As far as I know, biologists don’t have a firm set of predictions for even simple situations like this but tend to take a “let’s see what this does” approach.

        But again, perhaps I’m being too narrow. It seems to me that genetic engineering provides some support for Darwin’s theory. Though it still leaves the field of predictability pretty wide open, doesn’t it?

        That’s one of the things that makes the scientific approach so fascinating. One never gets to see the light at the end of the tunnel. Let alone arrive out into the wide open expanse of Total Knowledge.

        Again, thank you.
        Terry

        Terry Sissons

        19 July 2011 at 8:44 pm

  2. Thanks for this. I haven’t read What Darwin Got Wrong, but the Fibonacci section that you quote doesn’t seem to me any different from what D’Arcy Thompson said 100 years ago in On Growth and Form, a book which is beloved of many biologists (the edition I read has an introduction by Stephen Jay Gould). As I understand it, Thompson wasn’t disputing natural selection at all, just suggesting that physical constraints have an important role in determining physical form.

    Looking forward to the rest of your series.

    Jonathan

    17 July 2011 at 4:04 pm

    • Thanks Jonathan.

      Well, to be fair F&P-P did mention that the Fibonacci material came from D’Arcy Thompson (which I must get round to reading!), but it had never occurred to me before that anyone would have seen physical constraint-determined form as undermining natural selection. WDGW is one of the most ‘so what?’ books I’ve read in ages!

      Thanks again, Chris.

      Chris Lawrence

      18 July 2011 at 6:30 am

  3. Thank you for reading this book. It’s a relief to decide with a good conscience that I won’t bother. But I do look forward to your discussion of the intensional fallacy.

    Terry Sissons

    17 July 2011 at 2:04 pm


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