I have uploaded the slides from my second Pittsburgh lunchtime talk. This is an initial presentation of a current paper project. Here is the question: If science proceeds by (1) proposing a number of candidate explanations for a phenomenon, (2) ranking these explanations by explanatory power and (3) accepting the most highly ranked of the candidates, then why should we expect science to arrive at truth? After all, it is always possible that we simply failed to consider the true hypothesis in the first place. This would explain why so many successful — that is, highly ranked — past theories were later abandoned. In recent years this issue has been vigorously pursued by Kyle Stanford, who speaks of the “problem of unconceived alternatives”. In my talk I develop an account of why the problem of unconceived alternatives is not acute in much of the life sciences. More to follow.