Abstract The article considers the role of biological knowledge in the formation of modern holistic worldview, developed in the framework of global evolutionism, which has been established within the post-nonclassical scientific rationality. The studies of material in the history of science and the history of philosophy, as well as the works of modern authors, revealed the existence of contradictory quantitative (quantitativistic) and qualitative (qualitativistic) research programs in the development of knowledge and its worldview interpretations, which alternately claimed to dominate in science. On the basis of retrospective analysis of the science of living it is shown how the development of a qualitatively-holistic approach in biology helped to overcome the principles of reductionism and to what extent it can contribute to the introduction of significant adjustments to its methodology. The authors made an attempt to identify and justify a special role in this process of evolutionary and environmental studies, which serve as the basis for the formation of new promising theoretical and methodological programs based on the principle of integrity. The scientific novelty and relevance of the article consists in explicating on the biology material the heuristic and methodological significance of qualitativism as a cognitive-methodological approach in comprehending biological processes.