Traditionally, accounts of fundamental audit theory have been based on a “common sense" epistemological framework, incorporating a correspondence theory of truth and a “naïve empirical" approach to discovery and demonstration. Although these accounts generally fail to link this theory convincingly to audit practice, most writers on technical audit processes have assumed (usually implicitly) that no practical problems arise as a result of this. This disengagement between epistemological grounding and day-to-day practice is mirrored in some current writing, which takes its inspiration from the sociology of knowledge. This writing, also, fails to (and indeed cannot) engage in a discourse with practitioners on fundamental theory since it conceives the practitioner’s rationality as constructed, and, therefore, contingent. This paper attempts to set out an approach to fundamental theory, aimed at avoiding the errors of the early theorists; preserving the insights gained from the sociology of knowledge, without coming to grief on its self-referential difficulties; and suggesting a route towards reconciling practice with conceptual basics.