Abstract

While there is general agreement that knowing a proposition p involves knowing that nothing incompatible with p is true, there is much controversy over the range of possibilities that have to be ruled out if knowledge claims are to be sustained. With the failure of attempts on behalf of commonsense to delimit the range of counterpossibilities in order to leave room for knowledge, some theorists, most notably Adler, have sought to introduce a set of so-called ‘universalizability principles’ that require us to extend our epistemic judgments about particular beliefs to those held under similar circumstances. These principles, it is claimed, not only identify which counterpossibilities must be countenanced, but also have enough power to generate skeptical results. In this paper I distinguish between minimalist and full-blooded versions of the universalizability thesis, and argue that the thesis can have skeptical consequences only when conjoined with certain epistemically significant assumptions. This is followed by a discussion of the epistemic import of the minimalist version of the thesis by considering how it can arise naturally in epistemic contexts, in virtue of either being semantically linked to the concept of justification or as a result of enforcing certain constraints on its application.