Knowledge, Justification and Reason-Based Belief

Abstract

Can the ordinary concept of knowledge be defined in terms of justified true belief (‘JTB’)? We argue that the Gettier cases need not invalidate every analysis of knowledge in terms of justified true belief, depending on how the notion of justification is understood. We present a framework for the representation of reason-based belief and use it to define a notion of true belief supported by adequate reasons. An adequate reason is characterized as being infallible, namely as a justification supporting only true propositions. We give a tentative definition of knowledge in those terms. We present two variants of our axiomatics for belief, which differ mostly on how subjective and accessible the notions of reason and support are taken to be. A more detailed version of our approach and its model theory appears in an expanded version of this paper.