This article offers an approach that combines, on the one hand, the philosophical notion of reflexivity, which is related to the ideas of self-reference and paradox, and, on the other hand, the sociological discussion of epistemic reflexivity as a problem of coherence, which was mainly initiated by certain branches of ethnomethodology and social constructionism. This combinatory approach argues for reflexivity as an epistemic criterion of ontological coherence, which suggests that social ontologies should account for the possibility of self-reflective subjectivity - for otherwise they result in a paradoxical conclusion according to which a social scientist reflects on her or his ontological commitments even though these commitments deny her or him the capacity for self-reflection. This analysis presupposes that all human sciences are categorically premised on social ontologies; and it argues for an analytical distinction between self-reflection, which refers to the agential capacity for reflecting on one's own commitments, and the epistemic criterion of reflexivity hereby proposed. These two analytically distinct though interdependent socio-theoretical concepts are frequently conflated in the literature; thus, this article also aims at a 'clearing of the ground' that can be of categorical use to the human sciences.