This chapter contextualizes Ludwik Fleck’s epistemology, emphasizing his commitment to democratic values and collaborative knowledge production, and contrasting his inclusive vision of science with elitist models of knowledge control. It examines Fleck’s critique of Kurt Riezler’s neo-Kantianism and his alignment with Niels Bohr’s interactive framework, which inspired Fleck’s rejection of representational cognition and the notion of absolute reality. Extending Bohr’s insights beyond quantum physics, Fleck developed a socially interactive model of cognition. His marginalization in interwar Lwów informed his rejection of prevailing thought styles and reinforced his commitment to collective, historically grounded modes of knowing. The chapter then assesses Fleck’s relationship to the so-called Polish School of Philosophy of Medicine—a category whose coherence is itself debated. Drawing on Ilana Löwy’s work and more recent scholarship, it examines how figures such as Biegański and Kramsztyk articulated a patient-centred, holistic epistemology that emerged under conditions of political subjugation and professional exclusion. Fleck drew on this milieu—particularly its emphasis on therapy, specificity, and reflexivity—while remaining at its margins due to his position as a Jewish intellectual. Finally, in response to Thomas Schnelle’s interpretation, the chapter reconsiders Fleck’s critique of the Lwów School, especially his rejection of Twardowski’s emphasis on objectivity and the ideal of the neutral university instructor. In contrast to nationalist and universalist abstractions, Fleck emphasized the situated, collective, and evolving nature of cognition. His epistemology, shaped by marginalization, implicitly challenges the exclusionary structures of the interwar Polish university and advances a reflexive, open-ended model of knowledge.