If the theme of this volume—"Einstein meets Magritte"—evokes the possibility of an intersection or convergence of ideas between parties who never meet empirically, then the topic of the present essay can be seen as the reverse: that is, the possibility of a failure of convergence, intersection, or even engagement of ideas between parties who not only encounter each other in empirical space but repeatedly converse there. It is the structure and dynamics of such failed meetings, especially as they occur between traditional philosophers of science and theorists, historians, and sociologists working in the relatively new field of 'science studies," that I mean primarily to explore here. I am also concerned, however, with the more general theme and issue of in/commensurability, which figures centrally and by no means incidentally in the debates that divide them.