Infallibilism is the claim that knowledge requires that one satisfies some infallibility condition. I spell out three distinct such conditions: epistemic, evidential and modal infallibility. Epistemic infallibility turns out to be simply a consequence of epistemic closure, and is not infallibilist in any relevant sense. Evidential infallibilism i s unwarranted but it is not an satisfactory char...

We present a logic for belief revision in which revision of a theory by a sentence is represented using a conditional connective. The conditional is not primitive, but rather defined using two unary modal operators. Our approach captures and extends the classic AGM model without relying on the Limit Assumption. Reasoning about counterfactual or hypothetical situations is also crucial for AI. Ex...

The new …eld of judgment aggregation aims to …nd collective judgments on logically interconnected propositions. Recent impossibility results establish limitations on the possibility to vote independently on the propositions. I show that, fortunately, the impossibility results do not apply to a wide class of realistic agendas once propositions like “if a then b” are adequately modelled, namely a...