Rethinking holism and underdetermination

Mature scientific hypotheses are confirmed by large amounts of independent evidence. How could anyone be an anti-realist under these conditions? A classic response appeals to confirmational holism and underdetermination, but it is unclear whether traditional arguments succeed. I offer a new line of argument: If holism is interpreted as saying that the confirmation of every part of a hypothesis depends on the confirmation of the whole hypothesis, we must formulate conditions under which the confirmation received by the whole can be transferred to its parts. However, underdetermination suggests that relevant conditions are typically not met. If this is true, the confirmation received by the whole remains bounded by the priors for the parts, and we lack compelling reasons to believe substantive hypotheses based on evidence beyond the degree to which the posits involved in them are antecedently believed. A rejoinder comes from selective realism: If some posit is preserved throughout theory change, it is confirmed beyond the degree to which the containing hypothesis is. However, the variant of holism considered here exactly implies that we cannot confirm such posits in isolation. As I will show, the realist is thus forced into a dilemma: Either she succumbs to the holistic challenge, or she must embrace meta-empirical facts, such as the posit’s recurrence, as confirmatory.