Ninio presents an interesting and ambitious attempt to account for syntactic development from a lexicalist perspective with support from the power law of practice and complexity theory. She argues strenuously against a rule-based account of acquisition, preferring instead a purely word-specific syntax throughout acquisition and into adult language and sees the minimalist syntax merge/dependency operation coupled with analogical learning as the only machinery required.
This volume has a number of strengths, including the particularly good review of the range of accounts available for early two-word combinations and the presentation of merge/dependency. The discussion of the power law of practice raises some important issues and reminds us that we should always be prepared to revisit the idea that language acquisition is skill acquisition like any other, even if we ultimately disagree with this idea. Finally, the appeal to complexity theory and the suggestion that children hook into the world of speakers like Internet navigators hook into the Internet is provocative. It leads to the interesting claim that children neither reinvent nor internalize language but simply choose which items to learn to produce via the same pragmatic principles that adults use in choosing what to say.
Set against these positives are a number of negatives. The first surrounds the origins of the operation merge, given that it cannot, in Ninio's framework, be part of any sort of Universal Grammar hypothesis. She assumes that children “deduce the principle of the Merge/Dependency operation from sentences adults say to them, leaving the details of this learning process to some other study” (p. 31). Along similarly tantalizing lines, she makes brief reference to the possibility that recursion is not at first understood by children (note 20, p. 36). However, there is no explicit discussion of this claim and, thus, no way to explain the limits of recursion in either child or adult grammars.
Failure to adequately address the issue of constraints on syntax and syntactic development is a major difficulty. For example, whereas merge can explain how words can be combined, it does not explain why not all of the structures that can be built by merge are allowed in the child's or the adult's grammar or why some of the possibilities allowed in children's grammars are not allowed in adult grammars (i.e., children make errors). How do we explain, for example, why children and adults do not appear to try to combine either noun phrases or adjective-noun combinations recursively but only bare nouns (Roeper, Reference Roeper2007)? Under Ninio's account, a generalized rule would not be allowed. How, then, do children's lexicons come to permit the right set of facts?
Similarly, limits to analogical learning, a central feature of Ninio's account, require further elaboration. Take the constraints on what can be recursively combined and what cannot. English can embed one verb inside another only once (i.e., it is not recursive); thus, “Come see me” is grammatical, but “Come see talk to me” is not (Roeper, Reference Roeper2007). However, this is a logical possibility (found in other languages) and one that children might be expected to try. Why, then, do they not? Ninio would presumably argue that the input did not warrant recursion. However, other recursive parts of the grammar (e.g., “John's father's brother's sister's friend's …”) are also unlikely to be in the input with any degree of frequency, and yet children understand that they are possible.
One feature of Ninio's approach that is particularly disturbing is that comprehension is simply dismissed on the grounds that we have no access to children's minds (p. 128) and, therefore, can only be interested in what children will say next; this stance has a distinctively behaviorist flavor. Without attention to comprehension, we are left with no way to explain children's capacity for making sophisticated judgments about the interpretation of sentences. (See Roeper, Reference Roeper2007, for a review of these capacities.)
Overall, appeal to merge out of the context of minimalism needs far more commentary than it receives. Additionally, without an account of more complex syntactic development, the ambitious goals of this volume as a new theory of syntactic development remain unrealized.
