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This paper situates us within the context of an internal conflict in the Philosophy of Karl Popper. On the one hand, Popper is an ardent proponent of scientific realism – the view that science seeks to formulate true theories that depict the structure of the universe; and on the other hand, the very Karl Popper propounds Non-Justificationism in science –a negativist methodology which asserts that the logic of science seeks not the justification but the refutation of theories. This non-justificationism seems asymmetric to the realist optimistic ambition of justifying the reliability of scientific knowledge. To resolve this tension between realism and non-justificationism in Popper’s epistemology some philosophers have proceeded by revising his method of falsification (Imre Lakatos,), others have opted for a reinterpretation of his realism (Evandro Agazzi, Mario Alai,) while some have given an instrumentalist status to popper’s rationality of science (Peter Godfrey-Smith, Anthony O’Hear). Our argument in this Paper is that to resolve the contradiction within Popper’s rationality of science we have to situate the two conflicting theses (Realism and non-justicationism) within the general problem of Popper’s epistemology. That is, the problem of the conditions necessary for the growth of scientific knowledge. Thus, after examining the basic tenets of Popper’s realism and illustrating the levels of the opposition between realism and non-justificationism, we have gone beyond other solutions to defend the conflation of realism and non-justificationism as the condition for the growth of knowledge.  Popper thus emerges out of our analysis as a ‘critical realist’ who rejects ‘dogmatic optimism’ and creates ‘critical optimism’ in his evolutionary epistemology.


Karl Popper Non-justificationism Realism instrumentalism (anti-realism) critical rationalism optimism objectivity and Truth

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Basilis, D. S., & Shang, N. (2022). The Opposition between Realism and Non-Justificationism in Karl Popper’s Rationality of Science: In Search of the Conditions for the Growth of Knowledge. CENTRAL ASIAN JOURNAL OF LITERATURE, PHILOSOPHY AND CULTURE, 3(5), 52-67. Retrieved from


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