Popper's 'Rationality Principle' and 'Epistemic' Rationality: an Attempt at Reconciliation

'Situational Analysis' (SA) constitutes Popper's methodological proposal for the social sciences. There is an apparent inconsistency in the fact that, on the one hand, Popper maintains that we learn by 'trial and error-elimination' and, on the other hand, he declares that his 'Rationality Principle' (RP) has nothing to do with the epistemic account of rationality implicit in his 'evolutionary theory of knowledge and learning'. We claim that the most likely reason Popper makes such claim is that his formulation of SA is better interpreted as an extension of his view of the 'method' of history to the theoretical social sciences. In light of it we argue that the implementation of SA in the latter may require the adoption of an expanded 'Rationality Principle' (ERP) whereby scientists assume that individual actors exhibit both practical and epistemic rationality. We identify two variants of SA we denote as SA1 and SA2 according to whether they are grounded on ERP or RP respectively and discuss some approaches in the social sciences that are representative of each of them. We conclude that the adoption of ERP helps mitigating the absence of social interaction in Popper's formulation of SA.