 One might be tempted to think that all and only propositions expressed by analytic sentences can have a priori justification, and that propositions expressed by synthetic sentences can only have a posteriori justification. We should resist this temptation. A number of philosophers, beginning with Kant, have claimed that some synthetic propositions can have a priori justification. As we will discuss below, Kant thought that all moral propositions were synthetic but could be established only by reason. Moreover, if one considers what is fundamental to the two distinctions, there is no obvious reason to assume they would perfectly coincide. The analytic/synthetic distinction fundamentally concerns conceptual or meaning relations, specifically, whether the subject of a proposition contains the predicate or whether the proposition is equivalent to a logical truth. The a priori/a posteriori distinction is fundamentally epistemic, being concerned with whether experience is required for justification. Two such fundamentally different distinctions could coincide, but it is not immediately apparent that they do; it would take considerable work to show that they do.