Abstract: The article considers the opposition of the doctrines of pluralism and monism and their related principles of proliferation and unification in the context of the development of modern cognitive sciences in three important respects for philosophy of science: theoretical, methodological, and explanatory. The article criticizes T. Kuhn’s views of theoretical monism and extends the defense of theoretical pluralism undertaken in author’s previous publications devoted to the conception of theoretical complexes, aimed at the correct description of large groups of theories in the cognitive sciences, such as connectionism, moderate embodied cognition, etc. Pluralism is also defended in methodological dimension. Theoretical pluralism and methodological pluralism are represented as an inevitable consequence of the conception of theoretical complexes and its principle of proliferation calling for the creation/improvement of scientific theories and models which are both compatible and incompatible with respect to a number of basic ontological and methodological assumptions. Theoretical pluralism and methodological pluralism should promote progress with respect to a number of the so-called epistemic qualities, both associated with the approximation of the truth (e.g. predictive success, the ability to give unexpected explanations to known facts, etc.) and not so associated (empirical fit, simplicity according to some interpretations, and the broad scope of the proposed explanations). At the same time the author claims that it is currently not possible to draw a similar conclusion in relation to the explanatory context: if the strategy of explanatory monism or explanatory pluralism will turn out be the preferred strategy for the cognitive sciences should become clear in the course of further research.