Knowledge of grammar includes knowledge of syntactic probabilities*

1. GRAMMAR AND LANGUAGE FORM. 1.1. WHAT GAHL AND GARNSEY (2004) SHOW. There is widespread consensus that one of the tasks of a grammar is to describe the form of language. What Gahl and Garnsey (2004; henceforth G&G) show is that the description of both /t,d/-deletion and word and pause durations in American English needs to make reference to statements of the form ‘such-and-such a syntactic configuration has such-and-such a probability of occurrence in this context’. Therefore, in order to account for the form of language, the grammar needs to include probabilities. In particular, we argue that verb subcategorization probabilities, or VERB BIASES, must be part of the grammar, since the match or mismatch between verb bias and syntactic context affects form. In a critique of G&G, Newmeyer (2006; henceforth N) agrees that the description of /t,d/-deletion and of other aspects of pronunciation reflects probabilities. However, N argues that the relevant probabilities are ‘extra-grammatical’: ‘generalizations about usage lie outside of grammar per se’ (N, p. 2). We acknowledge that subcategorization probabilities are a function of USAGE—they are that by definition, in fact. But the fact that subcategorization probabilities are ultimately the result of language use is not at issue. What is at issue is whether speakers know subcategorization probabilities as part of their knowledge of grammar. To establish that this is the case, G&G provided evidence suggesting that subcategorization probabilities affect language form even in situations where only syntactic probabilities, not meaning biases, can guide language production. In the discussion to follow, we first clarify a point about the experiment reported in G&G and briefly comment on N’s suggestions for future research on this issue. We then compare N’s meaning-based account of verb bias to the notion of syntactic probability in G&G and show that the latter correctly predicts facts about language production and comprehension that are unexplained under N’s account. Finally, we consider N’s suggestions for future research in more detail, arguing that the suggested research cannot shed any light on the issue at hand.