Hayek’s ideas in economics and social philosophy are weel known and have already been thoroughly explored, but his ideas in epistemology and methodology have not. In particular, what Hayek calls ” antiphysicalism ” in social sciences needs much more analysis if we are to understand why Hayek states that economics cannot and should not be regarded as a ” social physics “. I will precisely analyse this thesis putting to work all of Hayek’s writings dealing with epistemological and methodological queries, and especially in reference to his work in neuropsychology (The Sensory Order, 1952). I will systematically reconstruct Hayek’s economic methodology and show that, as a whole, it is a genuine inference, the first premisse being based on a ” theory of economic knowledge “, the second one on a ” constructivist ontology of social reality “, and the conclusive argument being methodological dualism-but, perhaps surprisingly, a weak one.