There is a significant difference between the classic, non-classic and post-non-classic epistemology. Briefly this difference can be formulated as follows: classic epistemology- there is place the unambiguous determinism of the content of scientific knowledge by the properties of cognizable objects; nonclassic epistemology – there is place only the probabilistic determinism of the content of scientific knowledge by the content of cognizable objects; postnonclassic epistemology – there is place the creative constructivism of researchers in relation to cognizable objects, the result of which is the pluralism of scientific hypotheses, models and theories in relation to the same objects. The article provides a rational reconstruction of the conceptual core of post-non-classic epistemology against the background of its comparison with the principles of classic and nonclassic epistemology. The result of this reconstruction is the proposed in the article understanding of the core of postnonclassic epistemology as a set of principles "5 c": 1) constructivism of scientific cognition, 2) contextuality of science knowledge (its conventional and metaphoristical character), 3) cultural and social conditionality of the dynamics science knowledge, 4) communicative nature of the process of scientific cognition, 5) consensual nature of scientific truths (their social expert nature). To according the poststructuralism all of the principles based on a general laws functioning language.
