The current paper by Amaral and Roeper (henceforth A&R) presents many interes--ting ideas about first and second language acquisition as well as some experimental data convincingly illustrating the difference between production and comprehen--sion. The paper extends the concept of Universal Bilingualism proposed in Roeper (1999) to second language acquisition. As stated in the Introduction, the idea of Multiple Grammars (MG) is in some sense obvious in the context of second language acquisition, and in my opinion, it also accounts well for the increasing number of findings from psycholinguistic studies that the L1 continues to affect the L2 even at very advanced stages of acquisition. I am also very sympathetic to the Full Trans--fer/Full Access approach and the goal of dealing with apparent optionality in terms of more formal representations and testable predictions. In this commentary, I focus on some aspects of the theory which are left somewhat unclear. The issues that I address are the nature of complexity and the "size" of rules as well as the question of what constitutes conflicting (sub--)grammars. I also compare the MG theory to my own model of micro--cues (Westergaard 2009a, b), discussing some similarities and differences, the latter mainly due to the micro--cue model claiming that the rules of early child language are smaller and more specific than has previously been assumed.
Complexity and the 'size' of rulesThe rationale behind the MG theory is the minimalistic principle Avoid complex rules. This is an appealing concept, and fundamentally correct, to my mind, although complexity is difficult to define. A&R argue that simple rules should not contain exceptions and should not be contradictory. This is similar to the micro--cue model (Westergaard 2009a, b), where rules are formulated in such a way that they do not overlap.It is thus not difficult to accept that the rule provided in (3) in A&R is a complex rule, combining English S--aux inversion in questions and quotative inversion in declaratives. But it is not obvious to me that the two types of inversion are contradictory, if the S--aux rule is stated in terms of interrogative C (which I believe it should be). Thus, this complex rule seems to be combining two different phenomena, and there is very little motivation for merging them in the first place, in my view, not even a historical one, as the two processes arguably involved verb * I thank Merete Anderssen, Kristine Bentzen and Tom Rankin for helpful comments and discussion.