The article critically examines the project of Brian Epstein's social ontology. The authors propose to interpret a social fact as derived from the appropriate perspective of an observer carrying out a structural reconstruction of a social phenomenon and identify difficulties in the way of analyzing social facts as structurally independent of causally determining factors. The article shows that the determination and foundation of social facts cannot be understood as asymmetric, substantiates the symmetrical nature of the relationship between the determinable complex fact and the ontological foundations that determine them, and suggests that the judgments describing them are equivalent, and also proves the need to involve philosophical and scientific methodology, the resources of the philosophy of language and epistemology to address the issue of the validity of projects “ontological fixation”, which the authors of the article propose to consider as a scientific classification. Understanding the ontology of the social is possible only when going beyond its limits, and any classifications can be idiosyncrasies of individual classifiers or observers, scientifically unequal and requiring epistemological evaluation. The authors note that epistemology allows us to judge the necessity or, on the contrary, artificiality of classification, and the question of the ontological basis of a social fact should be solved by analogy. Accordingly, the search for such ontological foundations is not possible without prior resolution of the epistemological problem: which classifications (fixations) of “natural” or “social species” are structurally necessary (in the sense that their macro-properties properties stem from the internal structure), and which are arbitrarily constructed by the observer, based on his idiosyncrasy or local-historical, cultural or ideological position.