Abstract

Roche and Sober have offered a new argument for the view that a hypothesis H is not confirmed by its capacity to explain some observation O. Their argument purports to work by showing that O screens H off from the fact that H would explain O. This paper offers several objections to this argument. Firstly, the screening-off test cannot identify whatever evidential contribution Hs explanatoriness may make. Secondly, that H would explain O may be logically necessary, eluding the screening-off test. Thirdly, the test cannot detect an important difference that Hs explanatoriness often makes to Hs confirmation.