We propose a rational reconstruction of Sraffa’s strategy for theory assessment with a focus on the issue of the realism of the premises and the role of internal logical consistency as distinct from formal rigour. Sraffa appears to follow a two-stage strategy: first, a rigorous logical reconstruction of the theory under scrutiny and the identification of its explicit and implicit assumptions; second, an accurate description of the empirical phenomena the theory, once logically reconstructed, is able to explain. The explanatory value of a given theory depends on its ability to select among the various economic forces and mechanisms in action in a given situation the one(s) that the theorist holds to be the most relevant and provide a logically consistent description of the chosen mechanism(s). No theoretical explanation of a given economic phenomenon may be considered acceptable if it is based on ill-defined theoretical notions since such notions stand in the way of an exact theoretical measurement of the magnitudes under investigation and thus prevent the theory of being correctly applied to the phenomena it was designed to explain.