The British Journal for the Philosophy of Science vol:58 issue:3 pages:489-502
It is well known that according to the traditional Bayesian qualitative account of evidential support, when a hypothesis entails the evidence, the evidence not only supports the hypothesis, but also supports the conjunction of the hypothesis with any arbitrary further proposition. There is a widespread feeling that this is a counterintuitive result. This is known as the ‘tacking problem’ for Bayesian confirmation theory. After outlining a generalization of the problem, I argue that the Bayesian response has so far been unsatisfactory. I then argue the following. (i) There exists, either instead of, or in addition to, a two-place relation of confirmation, a three-place relation of confirmation, holding between an item of evidence E and two competing hypotheses (C(E, H1, H2)) (ii) The appropriate account of this three-place relation of confirmation is such that problem cases discussed all involve tacit reference to a contrast case H2 such that ~C(E, H1, H2). This solves my generalization of the tacking problem. I then conclude with some thoughts about the relationship between the traditional Bayesian account of evidential support and my proposed account of the three-place relation of confirmation.