The author states first praxeology's dilemma: if its theoremes are a priori in the unidimensional sense in which praxeology seems to be intended, then the theory as represented in the theorem is inapplicable. If it is not a priori in that sense, then praxeology is already defeated. In a concrete analysis of a part of a praxeological system the author shows that the contention which sees economic theory simply as the result of formal deduction starting from an a priori axiom is unfounded. As a language, praxeology is not ‘water-tight’; its line of reasoning must always draw from the inarticulate background of professional knowledge. Praxeology can be explained away as a process of dialectical redefinition of concepts, ultimately and inevitably dependent upon empirical hypotheses.