Projectibility and Science: Epistemic Challenges

Appealing to science is a popular suggestion for separating projectible predicates. According to this suggestion, we can expect science, eventually, to separate such predicates for us, rendering it unnecessary to make further attempts to explicate the criteria for projectibility. In this essay, I address three theoretical challenges to this suggestion. The first stems from the inductive character of science, which casts doubts on its efficacy in separating projectible predicates, since induction itself requires this separation. The second is the inferential externalism implied by this suggestion, whereas the problems of induction have bite only if inferential internalism is presumed. The third challenge appears when a strong relationship between projectibility and kindhood, on the one hand, and kindhood and similarity, on the other, is posited, such that a more projectible predicate is believed to be a predicate which tracks better similarities in nature. Now the question appears: whether and how science enables us to track better similarities? I distinguish two conceptions of similarity, one intuitive, the other theoretical, and I argue that the theoretical one is to be preferred, showing that how scientific practice involves shifting from an intuitive idea of similarity to a theoretical one. Through answering these three challenges, I attempt to support the appeal to natural science as far as Goodman’s problem of induction is concerned.