In this paper I begin with a recent challenge to the semantic approach and identify an underlying assumption, namely that identity conditions for theories should be provided. I suggest that this demand should be resisted and that the semantic approach should be seen as a philosophical device that we may use to represent certain features of scientific practice. Focussing on the partial structures variant of that approach, I then consider a further challenge that arises from a concern with the role of idealisations in that practice. I argue that the partial structures approach is capable of meeting this challenge and I conclude with some broader observations about the role of such formal accounts within the philosophy of science
