 Independent of issues regarding epistemic and ontological reductionism, philosophers sometimes allude to a distinction between epistemic and ontological forms of reduction. Sarkar (1992) suggests that a notion of reduction is epistemic if and only if it cashes out reduction in terms of explanation, presumably based on the assumption that the concept of explanation is an epistemic concept. Thus insofar it enters the concept of reduction, the latter is epistemic as well. On this view, an ontological concept of reduction would be one that is defined solely in non-epistemic terms.