"The goal of determining the precise nature of Universal Grammar is externally constrained in two ways. First, as we have mentioned, there is the fact that first language acquisition is uniformly successful (barring pathology) and that it is also astonishing rapid; by the age of four at the latest, children show clear evidence of having acquired all of the major grammatical properties of their particular language."There is nothing particularly controversial about this assertion in the context in which it was made, namely, in a book by a generative syntactician for other generative syntacticians. I don't know if I believed it then, or whether I just followed the prevailing rhetoric, but one thing is certain: it sits uneasily, to say the least, with the following quote from a commentary I wrote last year, and which has just appeared in Second Language Research. (Notice, incidently, the change from we to I: I'm not sure if this reflects greater humility or arrogance, and in what direction—most likely, I'm more comfortable in defending my own position, now, whatever others may say.)
"As someone who spends the greater part of his time in first language research, I am continually struck by the optimism displayed by second language researchers about young children’s language abilities. For the fact is that—barring a very few precocious exceptions—children do not perform like little adults either in terms of spoken language comprehension and production, or with respect to their performance in judgment tasks. Instead, they behave (unsurprisingly!) like children, deviating in a variety of interesting and systematic ways from the adults around them. Pace Hawkins, there is simply no empirical evidence for the claim that ‘children…acquire all the major structures of their language by the age of three-and-a –half [my emphasis: NGD]’; nor am I aware of any first language researcher who has advanced such a claim."
Oh dear. In a discipline that values consistency over credibility almost every time, this is very bad news, and, at least, a indictment on my own lack of scholarship. The puzzling thing is, though, that in spite of the clear contradiction, I don't really feel that I've taken a u-turn, to use political commentators' favourite metaphor. Instead, what is of interest is what such assertions are in (rhetorical) service of. Let me explain. In the passage that follows the latter (2009) quote, I wrote quite carefully:
"There is of course evidence supporting the view that children show sensitivity to subtle abstract constraints of the adult target grammar considerably in advance of their own productive capacities, and that they project far beyond the input in ways that are consistent with nativist explanations, but those are entirely different matters."They are, but the two are often conflated. All, I think, that most generativists intend by making such sweeping claims about acquisition is to refer to the mismatch between young children's language production and their capacity to make adult-like discriminations between well-formed and syntactically deviant utterances: i.e., that "children [are able to] project far beyond the input in ways that are consistent with nativist explanations." Having thus pointed the reader into the rhetorical flow of nativism, we then set about our own analyses, largely ignoring the general acquisition issues from there on. For this claim about projection to be legitimate, it doesn't have to be true that children have mastered the adult grammar by the age of three, four or five or indeed any age up to adulthood: even though early emergence of grammatical knowledge is considered to be one of the hallmarks of innateness (Crain 1991), it doesn't follow that late emergence runs against innateness; what matters, as Crain & Pietroski (2001) point out is the way in which the developmental trajectory is constrained...
I suspect now that the source of the difficulty is a failure adequately to distinguish between the capacity to "create grammar" and the capacity to "learn language". The only person I know of to clearly articulate the difference between these two with respect to theories of Universal Grammar is Wolfgang Klein, whose presentation will receive the attention it deserves in this monograph I'm supposed to be getting on with...
