In my dissertation project, I want to unravel the way assumptions about individual behavior determine theory choices in Economics. To do so, I will carefully reconstruct disputes within Economics in which the theories in question were based on differing assumptions about individual behavior, for example the Socialist Calculation Debate. By this I mean that I want to show which problems the theories in question were intended to solve, what exactly the content of the relevant assumptions about individual behavior is and in which way they influence the solutions for the problems that were ought to be solved. After doing so, I want to investigate the arguments that determined the decision for one of the competing theory within the mainstream of economics, especially with respect to their reference to the differing assumptions about individual behavior. I will then critically evaluate these arguments on the basis of classical positions within philosophy, such as critical rationalism, conventionalism and pragmatism to determine whether or not these arguments are sound. In doing so, I hope to contribute to ongoing debates within the philosophy of the social sciences.