Exchange with Fodor on Darwinism, University of Maryland, College Park, November 8th 2007

On November 7th and 8th, Jerry Fodor gave a series of lectures entitled “Against Darwinism” at the University of Maryland.  The text upon which the lectures were based can be found at:

I attended the lectures and had a few exchanges with Fodor during the discussion.  What follows is a transcript of our exchange on November 8th.  It gets a bit repetitive, so I’ll summarise:  Fodor argued that natural selection explanations are not causal; rather, they are historical.  I claim that there are non-causal explanations that are nevertheless non-historical (they appeal to general principles rather than only particular events).  My evidence for this is the ability of Darwinist explanations to render certain data non-mysterious, even if they do not do so by providing a causal explanation (in Fodor’s sense).

Me:  “We could just grant that you’ve established what the theory of natural selection isn’t: it isn’t a non-circular, non-trivial, naturalistic explanation.  OK.  But let’s look instead at what you say it might be, then, instead, if it’s not that.  And you offer: maybe it’s an historical account, an historical explanation.  But it seems to me that there might be another possibility, which is that it’s still an explanation, but not an historical one.  For instance, if you take the kind of scenario that we were hearing here, about the moths.  Back then you might have noticed that the colours change when you change their environment, but you still might be baffled about: how could that be? (Imagine a time before we had the account of natural selection around.)  And so now it counts as an explanation:  the way that moths’ colours match, the explanation for this counterfactual dependency, is natural selection.  You don’t have to appeal to some divine [power], you know, all the wrong explanations that were ever given for that data.  You could instead say, we actually know the explanation…

Fodor:  “I don’t actually think that natural selection is [?]  What happens when the dialog takes place?  The scientist says: “I wonder why all these moths change brown when they were white?”, and the Darwinist says: “I’ll tell you why!  It’s because there must be something about the moths, and something about the environment, or both, such that it’s because [the colours change in?] the environment that the months change colour.”  To which the scientist’s reply is: “Go away, stop bothering me, I’m busy.”  Of course *that’s* true:  it’s a truism.  I mean, of course there’s a causal relation of some sort…”

Me: “It’s a truism that wasn’t acknowledged until Darwin.”

Fodor:  “If moths change colour in a certain environment, then there must be something about the moths, or something about the environment…  that’s the truism, the question is…”

Me:  “Fortunately, natural selection says a little more than that, because you’re right:  that leaves the possibility that God or something steps in.  But it says that the factors that are relevant in the environment don’t include the intentions of Mother Nature, the intentions of a designer, God, it doesn’t require any special substance; it’s just a blind process of things dying out that don’t do well in the environment, then reproducing.  People found that to be explanatory.  They said:  “Good; it’s no longer a mystery why the colours of the moths track the colours of the environment so well.  We don’t have to appeal to God, we don’t have to appeal to some other special property.  We now know what it is.””

Fodor:  “That we don’t need God doesn’t make it not [an issue?].  It’s perfectly true, we don’t need God.  All sorts of silly theories are ruled out.  But they were ruled out by my initial formulation, namely:  there must be something about the environment, something about the moths, such that due to the interaction of those two things…  So, God’s not the intelligent designer.  That’s all built-in to what is still just a truism.  You’ve explained nothing when you’ve said: If A’s change a certain way in context B, then there must be something about A or B that causes the change.  Of course.  Unless the context is irrelevant…

Me:  “But it says more than that.  It says that the ones that don’t match in colour to the environment die off…  Sure, as the theorist I am deciding what are the relevant properties, but…”

Fodor:  “How do you like this explanation:  “the reason there are so many brown ones is that all the white ones are dead”?”

Me:  “Right!  That’s part of the natural selection explanation.”

Fodor:  “No, it’s banal! It’s empty!”

Me: “Well, if that were the only part of the natural selection explanation…”

Fodor: “What’s the rest?”

Me:  “The rest is that traits are passed from one generation to another, that the whiteness is passed to the white offspring…”

Fodor:  “You don’t have a notion of trait, and you certainly don’t have any access to the claim that it was the *whiteness* that changed the colour.  All you know is that there’s been a change of colour.  There’s been changes of millions of other coordinated properties, [which], especially since the [potential interactions?] have to be very local, are just about the properties of the…”

Me: “No; we’re already starting out wondering about the colour; we’re wondering why does the colour of the moths covary with the colour of the walls in the lab…”

Fodor:  “That’s question-begging!”

Me:  “No, that’s the data, and we want to explain the data.”

Fodor:  “No, the data tell you that there used to be lots of white moths around, and now there are lots of black ones.  The data doesn’t tell you…”

Me:  “No, I’m talking about the lab case.  I’m saying even in the lab case, where you see the data… All the data is, is that the colours of the moths track the colours of the walls, and you want an explanation for that.  And I’m saying that it’s hard for us to get back to a mind-set where we don’t have natural selection available.  And the fact is, people before Darwin would have been baffled about how the colours of the moths’ wings could track the colours of the walls.  We aren’t baffled, because we know that just having the ones that don’t have the “right” colours dying off, and passing on one’s traits to the next generation, is enough to explain the tracking of the colours of the moths’ wings with the colours of the walls.”

Fodor:  “The description is contentious, because you’re [packing a whole lot of choice benefit in the trait?]…

Me:  “That’s right: but we’re only interested in the colour.  We’ve decided…”

Fodor:  “That’s about *you*; that’s not about the world…”

Me:  “That’s right: we’ve chosen what fact we want to explain, and the fact we want to explain is the covariation of colour.  There are lots of other facts going on in that situation that we’re not interested in.  So we want to know:  what’s the explanation for *this* fact, and it’s natural selection that explains that fact.”

Fodor:  “When you say “we’ve chosen the relevant fact”, you’re saying we’ve also chosen the relevant [factors?]:  that is, changes in the temperature, blah blah blah, wouldn’t matter.  That’s fine:  As long as you’ve got something that’s sensitive to counterfactuals, you can tell the story.  The trouble is:  Mother Nature isn’t sensitive to counterfactuals.”

Me:  “Sure.”

Fodor:  “OK! So what’s the theory of selection?”

Me:  “The theory makes it non-mysterious, unlike for people before the concept of natural selection was available.  They would have been baffled about how it’s even possible for any trait to track some condition of the environment, at all.  And yet, we have a plausible explanation for how that’s possible.  Sure, there are lots of other factors that might be playing a role here, and we’ve decided to single out colour as the trait of interest, but…”

Fodor:  “No, no, no.  We’ve decided.. it’s not that we’ve decided to single out colour.  The assumption is that in fact, it’s evolved.  The question is [?]:  “what does it mean?””

Me:  “I didn’t even mention evolution:  I just said: “colour of moths tracking colour of environment”.”

Fodor:  “You mentioned something that claims counterfactuals.  You’re saying “If it had been green, the moths’ colour…”

Me:  “That’s right.  And we can do that in the lab.  We notice that.  We notice that if we make green walls, we get green moths; black walls, black moths.  And before Darwin, everyone would have been baffled.  And we don’t think there’s anything miraculous going on here. We think it’s just a matter of the ones that were coloured “wrong” dying out, and the ones that were coloured “right” passing on their “right” colour to their offspring, and that’s it.”

Fodor:  “Before Darwin they said exactly what we say after Darwin:  “Gee, there must be something about the colour of the moths and the colour of the walls in virtue of which the colour of one changes to match the colour of the other.”  And that’s a truism.  Once you’ve said that the counterfactuals…”

Me: “It’s more than that.  It’s about passing on properties to offspring…”

Fodor:  “I didn’t say anything about that…”

Me:  “I know, but the Darwinist does.  That’s why they’re saying more than that trivial…”

Fodor:  “Actually, the part of the Darwinist theory that [?] *you* is the one that says, “Look, dead animals have fewer offspring than living animals.  So if there is something about the wall, and something about the moth, in virtue of which all the brown moths die…” Actually, it’s the other way around: “…in virtue of which all the white moths die, then, if you could fill that in, you’d have a causal story.”  But nobody *ever* doubted that.  It’s just they had…”

Me:  “I didn’t say it was a causal story; I was just saying that it’s an explanation.  I was just trying to find out…  You were right about saying what it isn’t.  And I’m not trying to say that it’s a causal theory that’s explanatory, that’s natural, that’s non-trivial.  I’m just saying that it’s some kind of explanation that is non-historical, but nevertheless explains why moths’ wings’ colour can track the walls of the lab.”

Fodor:  “Yeah.  But that rules out essentially nothing, except that those aren’t the relevant properties, and that you got by stipulation.”

The chair stepped in at this point…


Upon re-reading crucial parts of Fodor’s text, I now think perhaps I should have just conceded that natural selection explanations are historical (in Fodor’s very liberal sense), but pointed out that this has no negative implications for natural selection, as many (most?) of our most respected, explanatory and successful sciences are similarly rendered “historical”.  Cf this passage from Fodor (p16-18):

“…[I]t’s crucial in the present case not just that there are bona fide successful adaptationist explanations, but also that such explanations are bona fide nomological. If they aren’t, then the success of the explanations is not a reason to think that there are laws of selection. In fact, I’m inclined to think that explanations of phenotypes in terms of their selection histories generally aren’t nomological and that they don’t claim or even aspire to be. What they are is precisely what they seem on the face of them; they’re historical explanations. Very roughly, historical explanations offer not covering laws but plausible narratives; narratives which (purport to) articulate the causal chain of events leading to the event that is the explanandum. Covering law explanations are about (necessary) relations among properties; historical narratives are about (causal) relations among events. That’s why the former support counterfactuals, but the latter don’t.

Historical explanations are as far as I know, often perfectly ok. Certainly they are sometimes
thoroughly persuasive, so perhaps they are sometimes true. But, prima facie at least, historical explanations don’t seek to subsume events under laws. `She fell because she slipped on a banana peel.’ Very likely she did; but there’s no law —there’s not even a statistical law— that has `banana peel’ in its antecedent and `slipped and fell’ in its consequent. Likewise, Napoleon lost at Waterloo because it had been raining for days, and the ground was too muddy for cavalry to charge. So, anyhow, I’m told; and who am I to say otherwise? But it doesn’t begin to follow that there are laws that connect the amount of mud on the ground with the outcomes of battles.

I suppose, metaphysical naturalists (of whom I am one) have to say that what happened at Waterloo must have fallen under some covering laws or other. No doubt, for example, it instantiated (inter alia) laws of the mechanics of middle-sized objects. But it doesn’t follow that there are laws about mud so described, or about battles so described, still less about causal connections between them so described; which is what would be required if `he lost because of the mud’ is to be an instance of a covering-law explanation. It likewise doesn’t follow, and it isn’t remotely plausible, that whatever explains why Napoleon lost at Waterloo likewise explains why Nelson won at Trafalgar; i.e. that there are laws about the outcomes of battles as such, of which Nelson’s victory and Wellington’s are both instances. `Is a battle’ doesn’t pick out a natural kind; it’s not (in Nelson Goodman’s illuminating term) `projectible`.”

So maybe Fodor’s right: there are no strict laws of natural selection.  But he is wrong in thinking that such laws would be the only way of ensuring that natural selection explanations are naturalistic, that is, that they involve no appeal to mentality or “unnatural” selection (in the sense of something that an agent does).



3 thoughts on “Exchange with Fodor on Darwinism, University of Maryland, College Park, November 8th 2007

  1. Hi,

    Sorry to eavesdrop but would the fact that Darwin’s idea of the evolutionary process as one of direct competition between parent species and the new variety for food have any bearing on your discussion? Wallace – who did know of the process before Darwin – saw it not as direct competition but as a process of change caused by environmental stress. For more on this and why it is Wallace’s ideas which deserve to be at the heart of your discussion and not Charles Darwin go to and order a copy of my new book.

  2. I think both you and Fodor (and perhaps all philosophers of science) ignore a type of explanation that I attempted to characterise in 1978 (in chapter 2 of The Computer Revolution in Philosophy namely explanations of how something (X) is possible.

    Such explanations do not typically provide sufficient conditions for X (though it is desirable to extend them so that they do so). So they don’t give a basis for predicting when X will occur, and they therefore don’t support counterfactual conditionals of the sort Fodor seems to be asking for. They also do not give necessary conditions for X, since showing a mechanism or process that could produce X does not demonstrate that only that mechanism or process could produce X.

    Many evolutionary explanations, and also explanations in linguistics and AI are explanations of how something is possible.

    I think there is more work to be done analysing such explanations and explaining their role in science and engineering.


  3. Aaron,

    Thanks for your comment. I agree that there are explanations of the kind you mention. And I agree that natural selection can provide an explanation for how is it possible that the colour of moths’ wings can track the colour of the walls. But I think natural selection can do more: it can explain not just how it is possible, but how it actually happened. The more and more you constrain the situation, of course, the harder it will be to distinguish between these two sorts of explanation.


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