The emergence of a single mutation that gives such a big advantage is derided by biologists as a “hopeful monster” theory; most evolution is gradual, operating on many genes, not one. Some ability like Merge may exist, but this does not explain why some words may merge and others don’t, much less why the world’s languages merge so differently.
So, what's wrong with Chomsky's idea is that such a big advantage could not possibly come from such a small change. This would be a "hopeful monster" theory and as we all know, these are false. How exactly? Here are several ways, some of which B&C could agree with.
Well, one might argue, as Hauser has here that there is more to the evolution of language than merge. Hauser does not deny that Merge is a big deal, but he thinks that getting the rest of the cognitive system up to speed so that it plays nicely with Merge is hardly trivial. He also thinks that there are changes to the conceptual system that need some explanation (the mystery of words/concepts) that also needs some discussion. I am pretty sure that B&C would agree with this. Their claim is not that given Merge there is nothing else to explain, rather that Merge is linguistically sui generis and that there is no piecemeal account for its emergence. Merge, or the recursive "trick," is an all or nothing affair.
Hauser agrees with this for the same reason that another rather well known evolutionary theorist does. To quote Dawkins from volume 2 of his autobiography:
As I mentioned on page 290, the main qualitative feature that separates human language from all other animal communication is syntax: hierarchical embedment of relative clauses, prepositional clauses etc. The software trick that makes this possible, at least in computer languages and presumably in human language too, is the recursive subroutine.
It looks as though the human brain must possess something equivalent to recursive subroutines, and it’s not totally implausible that such a faculty might have come about in a single mutation, which we should probably call a macro-mutation. (382)
So, maybe "Many scholars find this to be somewhere between insufficient, improbable and preposterous." But it would be nice to hear how they conceive of unbounded hierarchical recursion arising in the species.
Nor are the views expressed in B&C without credence among evolutionary mavens. It seems that some well known scholars do not find the B&C view of Merge absurd. Dawkins, someone who has dabbled in these areas, even gives a reason for why in this case he considers a macro mutation perfectly reasonable:
The reason I am prepared to contemplate macro-mutation in this case is a logical one. Just as you can’t have half a segment, there are no intermediates between a recursive and a non-recursive subroutine. Computer languages either allow recursion or they don’t. There’s no such thing as half-recursion.It’s an all or nothing software trick. And once that trick has been implemented, hierarchically embedded syntax immediately becomes possible and capable of generating indefinitely extended sentences. The macro-mutation seems complex and ‘747-ish’ but it really isn’t. It’s a simple addition – a ‘stretched DC-8 mutation’ – to the software, which abruptly generates huge, runaway complexity as an emergent property. ‘Emergent’: important word, that. (383)Note why: It's because "there is no such thing as half-recursion." Just so. So, wrt the recursive property characteristic of natural language it's one big jump or nothing. You can't jump the recursive canyon in several steps. And this is what B&C (and Dawkins) are saying. If Johnson (or the "scholars" he has consulted) thinks otherwise , it would be nice to hear his (their) story. Let's see how you get from finite to infinity in small deliberate steps. Note Dawkins observation that the problem is "logical" as "there are no intermediate steps between a recursive and a non-recursive subroutine." If this logical point is right, then Mr Johnson (and his scholars of note) have, as Lucy Ricardo used to say, "have some esplaining to do."
There is a tendency to go after Chomsky without actually presenting his arguments. This is one of those cases. I can see disagreeing with Chomsky's claims and conclusions. I have done so (to my horror) several times. Hauser did it in his brief review of B&C noted above. I can see arguing that an preferred argument doesn't pass muster. What I find remarkable is that gossip can pass as considered argument.
The problem of how language arose in the species is hard, the facts surrounding it are diffuse and the relevant questions worth addressing abstruse. Chomsky has articulated and defended a position in an area where this is a rarity. He has identified a feature of language that seems special to it (unbounded hierarchical structure) and noted that it calls for recursive capacities of a special sort. Moreover, he has noted that logically these capacities are an all or none affair. He might be wrong (though in this case I don't see how) but he has earned the right to be taken seriously. But he isn't. Why not?
It is pretty clear to me that there is an agenda: demonstrate that Chomsky is passed his sell-by date, that his views are batty and out of touch, that he is a crank. And if his scientific views are way out there and not worth serious consideration, then all the more his less technical (i.e. political) views. Is there an agenda? You bet there is! Are you surprised? I'm not.