For a Bayesian account of indirect confirmation

Laudan and Leplin have argued that empirically equivalent theories can elude underdetermination by resorting to indirect confirmation. Moreover, they have provided a qualitative account of indirect confirmation that Okasha has shown to be incoherent. In this paper, I develop Kukla's recent contention that indirect confirmation is grounded in the probability calculus. I provide a Bayesian rule to calculate the probability of a hypothesis given indirect evidence. I also suggest that the application of the rule presupposes the methodological relevance of non-empirical virtues of theories. If this is true, Laudan and Leplin's strategy will not work in many cases. Moreover, without an independent way of justifying the role of non-empirical virtues in methodology, the scientific realists cannot use indirect evidence to defeat underdetermination.