The article analyzes the impact of the principles of post non-classical science and epistemology and their inherent forms of rationality on the problem of wholeness. The authors substantiate the idea that by expanding the framework of systematic approach post non-classical epistemology and science bring to life the problem of wholeness, which predetermines the convergence of philosophical and scientific approaches to the concept of "wholeness”. The ontological and epistemological aspects of studying the holistic objects within the framework of post non-classical science achievements have been analyzed. The idea that post non-classical rationality also contributed to the widening of the set of concepts needed to describe the holistic objects is proved. The most significant influence of post non-classical period manifests itself in the problems of the existence of the holistic objects, their structure and transformation, substantiation of contingency and its role in the development of the holistic objects, the dialectics of the part and the whole.