What happens when social scientists and historians meet and talk? Historians of knowledge at MPIWG and social scientists funded by the ISRF share a critical view of knowledge. Historians insist that what counts as knowledge and how it is produced and exercised, has been different at different times. Among social scientists, the anthropologist will remind us that this difference exists, too, in different places and cultures, while the critically-minded political scientist will point to the to the effects of power on forms of knowing. All this, as the philosopher of science will suggest, entails that it will be different again in the future. What follows for the critical social scientist, generically, is that manifestly it needs to be constantly under review in the present; reflexivity is part of social science’s methodology.