Ability predicates, or there and back again

Abstract

Predicates like knowable, believable or evincible each are associated with Fitch-like paradoxes. Given some plausible assumptions, the prima facie reasonable hypotheses that what is true is knowable/believable/evincible entail, respectively, the decidedly unreasonable conclusions that what is true is known/believed/evinced. I argue that all Fitch-like paradoxes admit of a common diagnosis and give a uniform semantics for predicates like knowable that avoids the paradoxes while accounting for the intuitive meaning of these predicates. Moreover, I argue that a semantics of the same shape is to be given to similar predicates like erasable or legible, whose simple analyses likewise face broadly Fitch-like problems. This semantics also highlights and explains the context-sensitive nature of such predicates.