The aim of this article is to discuss and develop the diagnose of the Hardy-Weinberg law made by van Fraassen (1987, p. 110), according to which: 1) that law cannot be considered a law used as an axiom for the classical population genetics as a whole, since it is an equilibrium-law that holds only under certain special conditions; 2) it just determines a subclass of models; 3) its generalization shades off into logical vacuity; and 4) more complex variants of the (...) law can be deduced for more realistic assumptions. The discussion and development of such a diagnose will be carried out with the notions of another semantic conceptions of theories, related to that of van Fraassen, namely, the structuralist view of theories, and a rational reconstruction of classical population genetics made within the framework of such a metatheory, also presented in this paper. (shrink)