13 Nov 2018

On the integration of linguistics and cognitive science

William Matchin has had a couple of good posts on the Faculty of Language blog discussing the prospects for generative theory being realized within cognitive science. In response to the second I shared some thoughts on why generative theory is itself responsible for some of the lack of good feeling towards it and I thought I'd collect the main points here:

One thing I'd add is that Chomsky's revolution was essentially a revolution in philosophy of mind and there's no doubt that his mentalist project has been sidelined by people using [the tools of generative grammar (GG)] only for language description, but I think this is only half the story, in that the basic methodology of GG is in some ways responsible for the disregard for the mind that we're talking about.

If you look at Berwick et al.'s 2011 PoS Revisited paper, for example, you get a very clear statement of the idea that generative linguistics is all about describing attained adult competence with a view to determining the nature of its computational component, all theories of acquisition, development, cognition and evolution being interesting but methodologically 'secondary'.

Setting aside the epistemic issue of whether it's actually possible to have a theory of what's attained without a theory of how it's implemented, if you take this approach, you legitimize ignoring everything except language description because, in describing language, you are describing the mind, so long as you've paid lip service to Plato's Problem.

I think this makes the linguist/languist distinction* a little problematic because, so long as language description is held to be a cognitive project in its own right, we can argue about people's motivations, but there is essentially nothing besides exposition that distinguishes GG linguistics from languistics. Yes, GG at heart says that you should describe languages with a more ultimate cognitive aim, but it also says that you can achieve this aim while doing nothing but describing languages.

Thus, we do get some languists who rehearse Plato's Problem (PP) and Darwin's Problem (DP) only as a kind of ritualistic invocation, but at the same time, other linguists rehearse PP and DP because they're serious about linguistic nativism, yet the importance of these problems has been recognized for decades and GG has done basically nothing with them—its only contribution to the theory of acquisition is still its suggestion of what is not learned, and its only contribution to the theory of language evolution is its suggestion of what is not evolved by bread and butter natural selection.

Now, one response to this pessimistic picture is that I'm being unfair because we're dealing with different levels of description and it's too much to demand that people target the computational system and its implementation in one go. Thus, you end up with the Ian Roberts position that it is viable to have a 'platonic' linguistics [i.e. one that only talks about languages in the abstract without getting into their cognitive substance].

But let's be honest, for a start. This isn't any genuine philosophical Platonism—we're working on a theory founded upon an interest in the mind, bounded by conditions on what the mind can contain—'Platonism' here is just a polite word for having no interest in cognitive science because it's all brain stuff and stats.

I do think that avoiding interdisciplinarity is just fine, taken so far—it has after all been our strategy for many years and we have managed to get a lot right in GG—but taking an essentially metaphysical approach to what must be recognized as a psychological project has given us a theory that is, I think, absolutely rife with metaphors for things that go on in the brain, many of which may be quite misleading in ways that we don't yet realise.

[More specifically, this is because generative theory's standard fare is to give computational descriptions of language use, yet there is no guarantee that these descriptions hold in any non-trivial way of computations that are mentally represented. Or, to put it in blunter terms, you can't just give a syntax tree to a piece of performance data and say that I-language is this but in between the ears. The theory supposes that there is nothing problematic about how it transposes descriptions of E-language onto a model of I-language but all it has here is supposition.]

Crucially, I think this means in the end that we're kidding ourselves if we think that GG is simply describing reality at an abstract level in a way that we are not yet ready to reduce to the physicality of wetware and so on. Rather, I think we fundamentally do not know how to make GG into a theory that is fit for reduction, regardless of when it will be possible, because we haven't put in the necessary theoretical work—never mind any of the brain stuff—and this is largely because it's a basic principle of GG that it's always someone else's problem.


*This is a generally helpful dichotomy coined by Norbert Hornstein on his blog to distinguish those interested in language as a cognitive faculty (i.e. the linguists) from those interested in languages as social constructs (i.e. the 'languists').