The two faces of compatibility with justified beliefs

Research paper by Tero Tulenheimo

Indexed on: 23 Apr '15Published on: 23 Apr '15Published in: Synthese


When discussing knowledge, two relations are of interest: justified doxastic accessibility\(S\) (for all the agent is justified in believing in \(x\), she is in \(y\)) and justification equivalence\(E\) (the agent would have in \(y\) exactly the same justified beliefs that she has in \(x\)). Speaking of compatibility with the agent’s justified beliefs is potentially ambiguous: either of the two relations \(S\) or \(E\) can be meant. I discuss the possibility of identifying the relation of epistemic accessibility\(R\) (for all the agent knows in \(x\), she is in \(y\)) with the union of \(S\) and \(E\). Neither Gettier’s examples nor the ‘fake barn’ cases contradict this identification. However, the proposal leads to justification equivalent scenarios being symmetric with respect to knowledge: we cannot know a true proposition in a scenario if it is false in a justification equivalent scenario. This analysis may appear to render non-trivial knowledge impossible. This conclusion follows if the extra premise is granted that for all relevant true propositions there is a justification equivalent scenario in which the proposition is false. I provide a meaning-theoretic argument against this premise. I conclude by pointing out problems that would ensue from giving up the proposed connection between \(S\), \(E\) and \(R\) and allowing asymmetry of justification equivalent scenarios relative to knowledge.