In this paper I address some shortcomings in Larry Laudan's normative naturalism. I make it clear that Laudan's rejection of the "meta-methodology thesis", or MMT is unnecessary, and that a reformulated version MMT can be sustained. I contend that a major difficulty that attends Laudan's account is his contention that a naturalistic philosophy of science cannot accommodate any a priori justification of methodological rules, and consider what sort of naturalism might best replace Laudan's. To do this, I discuss Michael Friedman's (...) account of a relativised a priori and show that it is consistent with naturalistic philosophy of science and that it can help form the basis of a plausible normative naturalism. In particular, this Discussion shows that Laudan's rejection of any a priori justification of methodological rules is unjustified and inconsistent with scientific practice. Finally, I point the way to a version of normative naturalism that includes MMT and accounts for the role of constitutive a priori principles within science. (shrink)