Hayek's and Mises's argument for the impossibility of socialist planning is once again popular. Their case against socialism is predicated on an account of the nature of knowledge and social interaction. Hayek refined Mises's original argument by developing a philosophical anthropology which depicts individuals as tacitly knowledgeable rule-followers embedded in a 'spontaneous order' of systems of rules. Giddens, whose social theory is informed by his reading of Wittgenstein, has recently added his sociological support to Hayek's 'epistemological argument' against socialism. With (...) the aid of an interpretation of Wittgenstein which emphasizes his philosophy of praxis , I attempt to 'deconstruct' Giddens's and Hayek's 'picture' of tacit knowledge and rule-following on which their argument against socialism is predicated. (shrink)