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Dmytro Sepetyi

Zaporizhzhya State Medical University, Ukraine

[email protected]


Essays on Karl Popper’s and William Bartley's Philosophy


This is a collection of papers which initially have been written separately as discussions of different aspects of Popperian thought. There happened to be one recurrent issue addressed in most of this papers, and this issue had given the name to the collection. The issue is: how are we to understand correctly Popper’s-Bartley’s non-justificationism – the thesis that justification of our theories, statements and other positions is impossible and that we can well do without it with no impairment to rationality. I think that there is much of misunderstanding about this these both among Popper’s opponents and Popperians – too radical interpretations which aren’t warranted by Popper’s and Bartley’s explanations and arguments and which make critical rationalism look as a sheer absurdity. We need be careful to see what Popper and Bartley did mean – and what they didn’t mean – by “justification” when arguing that it is impossible and unneeded; what is that “justification” to which their argument apply. And we need to understand that there are other things which may be (and, in fact, are sometimes) called “justification” (in full accord with the common-language meaning of the word) to which Popper’s and Bartley’s arguments don’t apply. Also, the description of Popper’s theory as ‘negative’ rationality or model of reason (instead of ‘critical’) is conductive to grave misunderstanding.

Popper and his followers have spent huge amount of time and efforts to refute ‘the positivist legend’ about Popper’s philosophy – the legend which represented Popper’s philosophy as a variety of positivism. I am afraid that now this legend is (not fully, but to a large extent) replaced not so much with an adequate understanding as with the opposite, and just as much detrimental, negativist legend about Popper’s philosophy.


Published Articles

Sepetyi, D. (2021) Karl Popper’s solution to the problem of induction and the non-justificationist conception of rationality. Actual Problems of Mind 22.

Sepetyi, D. (2020) Non-justificationism and the negativist legend about Karl Popper’s philosophy. Actual Problems of Mind 21.

Sepetyi, D. (2019) The Third Realm and the Failure of its Naturalization in Karl Popper’s Conception of World. Visnyk of the Lviv University Series Philosophical Sciences 23: 5-11.


On Karl Popper’s philosophy

·  Three Popper’s Theories to Be Distinguished and Two Misinterpretations to Be Avoided

·  What Falsification Comes to


On William Warren Bartley’s philosophy

·  Critical Rationalism, Comprehensiveness and Extra-Rational Judgements

·  Comprehensively Critical Rationalism: Rationality with Revisable Foundations

·  On Alleged Flaws of Pancritical Rationalism (Criticisms of Antoni Diller's criticisms of pancritical rationalism in the paper “On critical and pancritical rationalism”)


On David Miller’s philosophy

·  In Defence of Reasons and Other Criticisms of D.Miller’s Critical Rationalism

·  PS. Reply to David Miller’s Reply. Where is the Place for Insufficient (Tentative) Reasons in a Non-Justificationist Philosophy?

·  Why Entertaining a Hypothesis is not the Same with Accepting (Classifying) It as True


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