This paper addresses two examples due to Peter Achinstein purporting to show that the positive relevance view of evidence is too strong, that is, that evidence need not raise the probability of what it is evidence for. The first example can work only if it makes a false assumption. The second example fails because what Achinstein claims is evidence is redundant with information we already have. Without these examples Achinstein is left without motivation for his account of evidence, which uses (...) the concept of explanation in addition to that of probability. (shrink)

The paper distinguishes between instrumental reasons and instrumental rationality. It argues that instrumental reasons are not reasons to take the means to our ends. It further argues that there is no distinct form of instrumental reasoning or of instrumental rationality. In part the argument proceeds through a sympathetic examination of suggestions made by M. Bratman, J. Broome, and J. Wallace, though the accounts of instrumental rationality offered by the last two are criticised.

Recently in this journal Sherrilyn Roush (2004) defends positive relevance as a necessary (albeit not a sufficient) condition for evidence by rejecting two of the counterexamples from my earlier (2001) work. In this reply I argue that Roush's critique is not successful.