Is Gerard Debreu a Deductivist? Commentary on Tony Lawson's Economics and Reality

Tony Lawson has argued that the methodology of neoclassical economics is deductivist: in constructing their formal models, economists hope to be able to provide explanations based on laws, as described by the deductive-nomological model of explanation. This article argues in contrast that neoclassical economics cannot be understood as following just one methodology. It is argued that neoclassicism exhibits two methodologies, one “official” and one tacit. The former is empiricist, and corresponds to the practice that has been described by Lawson. The latter, which can be called “hypothetico-deductive rationalism”, amounts to the position that knowledge of the world can be obtained without any empirical verification of one's assumptions, simply by exploring the implications of the assumptions one makes.