On Likelihoodism and Intelligent Design

Two common and plausible claims in the philosophy of science are that (i) a theory that makes no predictions is not testable and (ii) one cannot confirm a theory by criticizing a competing one absent further assumptions about their relation. Elliott Sober has developed these claims within likelihoodism, which defines the testability and confirmation of a theory only in contrast to another, and has argued that the claims hold for intelligent design (ID) when contrasted with evolutionary theory (ET). I show that Sober’s arguments rely on a contentious hidden premise, and that within likelihoodism, both claims are false for ID and ET under his assumptions and one very weak further assumption about ID and ET. I then show that, given Sober’s assumptions, the claims are true for a non-contrastive criterion of testability close to the Bayesian one and the relevance criterion of confirmation. §