 A much more general criticism has been advanced against van Fraassen’s version of a pragmatic theory by Kitcher and Salmon (1987). Basically, their complaint is that the relevance relation R in van Fraassen’s account is completely unconstrained, with the (in their view, obviously unacceptable) consequence that for any pair of true propositions P and A, answer A is relevant to P via some relevance relation and thus “explains” P. For example, according to Salmon and Kitcher, we might define a relationship of “astral influence” \(R^*\), meeting van Fraassen’s criteria for being a relevance relation, such that the time t of a person’s death is explained in terms of \(R^*\) and the position of various heavenly bodies at t. Here it may seem that van Fraassen has a ready response. As noted above, on van Fraassen’s view, background knowledge and, in the case of scientific explanation, current scientific knowledge, helps to determine which are the acceptable relevance relations and acceptable answers to the questions posed in requests for explanation—such knowledge and the expectations that go along with it are part of the relevant context when one asks for an explanation of time of death. Obviously, astral influence is not an acceptable or legitimate relevance relation according to modern science—hence appeal to such a relation is not countenanced as explanatory by van Fraassen’s theory. More generally it might be argued that available scientific knowledge will provide constraints on the relevance relations and answers that exclude the “anything goes” worry raised by Salmon and Kitcher—at least insofar as the context is one in which a “scientific explanation” is sought.