 The more interesting issue is whether supervenience suffices for reduction (see Kim 1984, 1990). This depends upon what reduction is taken to require. If it is taken to require property identity or entailment, then, as we have just seen  (Section 3.2),  even supervenience with logical necessity is not sufficient for reduction. Further, if reduction requires that certain epistemic conditions be met, then, once again, supervenience with logical necessity is not sufficient for reduction. That A supervenes on B as a matter of logical necessity need not be knowable a priori.