C&T deserve credit for their concern for attaining empirical evidence, in particular evidence from language acquisition, for linguistic theory. They also deserve credit for bringing to the attention of the linguistic community the fact that variations in methodology do indeed produce variations in child behaviours, a fact well appreciated in behavioural sciences such as psychology, but often not fully appreciated outside of it; in particular, not in linguistics, a field which is fundamentally and rightfully ambivalent about its standing as a behavioural science, considering its relation to mathematics and formal theory as well as to sociolinguistics (Lust, Flynn, Foley & Chien, 1999). C&T also deserve credit for their appreciation of the importance of what children do NOT do (constraints) in language, and attempts to empirically verify such.