Does Modern Evidence Refute Chomskyan Universal Grammar?

Scientific American says, in a recent article, “Evidence Rebuts Chomsky’s Theory of Language Learning” …

Does it?  Well, sort of.  Partly.  But not as definitively as the article says.

Michael Tomasello, whose work I love, argues in the article that Chomsky’s old idea of a universal grammar is now obsoleted by a new “usage-based approach”:

In the new usage-based approach (which includes ideas from functional linguistics, cognitive linguistics and construction grammar), children are not born with a universal, dedicated tool for learning grammar. Instead they inherit the mental equivalent of a Swiss Army knife: a set of general-purpose tools—such as categorization, the reading of communicative intentions, and analogy making, with which children build grammatical categories and rules from the language they hear around them.

Here’s the thing, though.   Every collection of learning tools is going to be better at learning some things than others.   So, for any collection of learning tools that is set to the task of learning grammar, some grammars will be easier to learn than others.  That is, given a certain set of social and physical situations, any particular of learning tools will be biased to learn certain grammars for communication in those situations, as opposed to other grammars.

So if humans have a certain set of universal learning tools, it follows that humans have a certain “universal probability distribution over (situation, grammar) pairs.”

This is not exactly the same as a universal grammar in the classic Chomskyan sense.  But just how far off it is from what Chomsky was thinking, remains to be understood.

For instance, more recent versions of Chomsky’s ideas view a sort of linguistic recursion as the core principle and tool of universal grammar.   Does our collection of human learning tools give us a strong bias to learn grammars involving certain sorts of linguistic recursion, in humanly common physical/social situations?   It may well.

Does the fact that some obscure grammars like Piraha appear not to have much recursion in their grammar refute such a possibility?  Not really.  It appears likely the Piraha have recursion in their linguistic repertoire, but just carry out this recursion more on the pragmatic and cross-sentential level, rather than on the level of syntax within individual sentences.  But that’s one obscure language — and the fact that a certain linguistic form does not appear in EVERY human language, does not refute the idea that there is a universal probabilistic bias toward this form in the human brain.

I’m not just splitting hairs here.   The question is to what extent has evolution honed the set of learning tools in the human mind for learning particular sorts of linguistic forms.   Tomasello’s intuition seems to be: not that much.  That is, he seems to think that our learning tools basically evolved for more general perceptual, motor and social learning, and then we just use these for language learning as well.   This is possible.  However, it’s also possible that our toolset has been substantially honed by evolution for the particularities of language learning — in which case there is a meaningful “universal human bias for learning certain types of grammars”, which can be thought about as a more modern incarnation of many of Chomsky’s ideas about universal grammar.

This issue is also relevant to AGI, because it has to do with how much attention AGI designers should spend on learning algorithms that are tuned and tweaked for language learning in particular, as opposed to expecting language learning to just pop out from application of general-purpose learning tools without any special language-oriented tuning.

Clearly Chomsky proposed a lot of strong ideas that just don’t hold up in the light of modern data regarding child language learning.  However, sometimes science (like many other human endeavors) can be a bit too much of a swinging pendulum, going from one extreme all the way to the other.  I wonder if the wholesale rejection of universal-grammar-related ideas in favor of usage-based ideas may be an example of this.  I wonder if we will find that the specific assemblage of learning tools in the human mind is, in fact, very well tuned by evolution to make learning of some specific grammatical forms especially easy in evolutionarily commonplace human situations.