Karl Popper was one of the most influential philosophers of science in the twentieth century. When scientists discuss methodology, they frequently refer to his ideas. For example, Nobel Prize laureates such as Friedrich Hayek, Peter Medawar, and John Eccles have all acknowledged Popper's influence.
Hayek described himself as a “complete adherent to his general theory of methodology” (Weimer & Hayek, 1982, p. 323). Medawar called Popper “the greatest philosopher of science that has ever been” (Magee, 1974, p. 9). Similarly, Eccles advised others to “read and meditate upon Popper’s writings on the philosophy of science and to adopt them as the basis of operation of one’s scientific life” (Eccles, 1970, p. 116).
However, Karl Popper was late. All of his essential ideas on the scientific method were preceded by the Polish philosopher and logician Jan Łukasiewicz (Woleński, 1998, p. 15). In his On the Creative Elements in Science (1912), On Science (1915), and On Reasoning in the Natural Sciences (1929), Łukasiewicz expressed the core claims of what would later be recognized as Popper’s view of the scientific method. In turn, Popper’s first book, The Logic of Scientific Discovery, was published in 1934.1
For the sake of justice and the desire to know, this essay aims to bring a curiosity known in academia to a broader audience. What exactly, then, are the parallels between Łukasiewicz and Popper?
Firstly, both philosophers believed that hypothesis formation is not a logical but a purely psychological and creative process (Woleński & Agassi, 2010, p. 383). As Łukasiewicz put it, “every theory is a creative act of man, not a reproduction of facts” (Łukasiewicz, 1915, p. xxii). In coming up with a theory, observation serves only as “a mere stimulus” (Łukasiewicz, 1912, p. 11), while the actual work is a matter of “the free intuition of researchers” (Łukasiewicz, 1929/2010, p. 388). Popper held the same view (Popper, 1934/2002, pp. 8-9).
Secondly, a related view they shared is that there is no logical way to establish that there is any evidence at all for any given scientific claim since no rules of such reasoning can be justified (Sinisi, 2004, p. 231). “All hitherto known attempts,” according to Łukasiewicz, “to ground inductive logic did not result in such formulations of its principles as would have an essential scientific significance and could be applied in natural science” (Łukasiewicz, 1929/2010, p. 387). In Popper’s words, “if a certain degree of probability is to be assigned to statements based on inductive inference, then this will have to be justified by invoking a new principle of induction, appropriately modified. And this new principle of induction, in turn, will have to be justified, and so on” (Popper, 1934/2002, p. 6).
Thirdly, both philosophers held not only that there is no such thing as inductive evidence but also that science does not use induction at all (Woleński & Agassi, 2010, p. 383). As Łukasiewicz stated, “One says that natural sciences employ inductive inferences, contrary to mathematics as a deductive science. I consider this view erroneous” (Łukasiewicz, 1929/2010, p. 386). In agreement, according to Popper, “we never draw inductive inferences, or make use of what are now called 'inductive procedures'” (Popper, 1956/1983, p. 35). But how does science work if not by induction?
The answer lies in that “in the scientific procedure, deductive inference plays an essential role, especially when we deduce sentences about empirical facts from accepted hypotheses” (Łukasiewicz, 1929/2010, p. 387). Thus, even though “we have no scientific criteria motivating us to assert some hypotheses [...] principles of deduction frequently lead us to reject some hypotheses” (Łukasiewicz, 1929/2010, pp. 387-388). For Łukasiewicz, as for Popper, the essential method of science consists of conjecturing hypotheses and then testing them by deducing their observational consequences (Woleński & Agassi, 2010, p. 383).
Besides similarities, there are also differences between the two figures. Notably, one difference is that according to Popper, statements of observational consequences—singular empirical statements—cannot be verified, whereas Łukasiewicz believes they can be verified absolutely (Woleński, 1994, p. 189). This means, surprisingly to many, that for Popper, scientific claims cannot be falsified either. As he explains, “Every test of a theory, whether resulting in its corroboration or falsification, must stop at some basic statement or other which we decide to accept” (Popper, 1934/2002, p. 86). The problem is, however, that “Experiences can motivate a decision, and hence an acceptance or a rejection of a statement, but a basic statement cannot be justified by them” (Popper, 1934/2002, pp. 86–88). In contrast, Łukasiewicz believes that the statements in question are “about facts given in experience, hence singular and certain statements” (Łukasiewicz, 1915, p. XXIV). This, interestingly, positions not Popper but Łukasiewicz closer to the views of the majority claiming adherence to the former.2
Setting aside the differences and one’s evaluation of the views of the discussed figures, it is fascinating to observe the same idea developed earlier and in a location different from where it is usually associated. Moreover, that is not the end of Łukasiewicz’s originality and contributions.3 For instance, he was the first to develop many-valued logic, where statements can be neither true nor false (Brożek, 2022, p. 209), and criticized the analytic-synthetic distinction already in 1924, long before philosopher and logician W.V.O Quine popularised doing so (Brożek, 2022, p. 217). Additionally, originality also characterises the philosophical movement of which Łukasiewicz was a major figure, namely, the Lvov-Warsaw School of philosophy. Interestingly, besides making significant contributions to the development of logic in the 20th century (Woleński, 1998, pp. 14-15), the school differed in several respects from the far more famous logical empiricism. For example, unlike many logical empiricists, it did not reject metaphysics or ethics as meaningless, nor did it confine philosophy to the analysis of language or dismiss introspective psychology (Woleński, 1989, pp. 295-301).4
Bibliography
Brożek, A. (2022). Jan Łukasiewicz's Program of the Logicization of Philosophy: Its Genesis, Content, and Realizations. Synthese, 200(199), 1-15. https://doi.org/10.1007/s11229-022-03699-7
Eccles, J. C. (1970). Facing Reality. Springer.
Giedymin, J. (1985). Polish Philosophy in the Interwar Period and Ludwik Fleck's Theory of Thought-Styles and Thought-Collectives. In R. Cohen & T. Schnelle (Eds.), Cognition and fact: Materials on Ludwik Fleck (pp. 179-215). Reidel.
Łukasiewicz, J. (1912). O Twórczości w Nauce [On the Creative Elements in Science]. In Księga pamiątkowa ku Uczczeniu 250-tej Rocznicy Założenia Uniwersytetu Lwowskiego przez Króla Jana Kazimierza (pp. 3-15). Uniwersytet Lwowski. (Reprinted in Łukasiewicz, 1961, pp. 66-75; English translation in Łukasiewicz, 1970, pp. 1-15).
Łukasiewicz, J. (1915). O Nauce [On Science]. In A. Wydawnictwo, I. Hefflicha & S. Michałskiego (Eds.), Poradnik dla Samouków (pp. xv-xxxix). (Reprinted in Łukasiewicz, 1998, pp. 9-33).
Łukasiewicz, J. (2010). On Reasoning in Natural Science [O Rozumowaniu w Naukach Przyrodniczych] (J. Woleński & J. Agassi, Trans.). History and Philosophy of Logic, 31(4), 381-388. https://doi.org/10.1080/01445340.2010.503388 (Original work published 1929).
Magee, B. (1974). Popper. Frank Cass.
Simons, P. (2023). Jan Łukasiewicz. In E. N. Zalta & U. Nodelman (Eds.), Stanford Encyclopedia of Philosophy (Spring 2023 ed.). Stanford University. https://plato.stanford.edu/archives/spr2023/entries/lukasiewicz/
Weimer, W. B., & Hayek, F. A. (1982). Weimer–Hayek Discussion. In W. Weimer & D. Palermo (Eds.), Cognition and the Symbolic Processes, Volume 2 (pp. 321-339). Lawrence Erlbaum Associates.
Woleński, J. (1994). Some Polish Contributions to Fallibilism. In G. Debrock & M. Hulswit (Eds.), Living Doubt: Essays Concerning the Epistemology of Charles Sanders Peirce (pp. 187-196). Springer.
Woleński, J. (1989). Logic and Philosophy in the Lvov–Warsaw School. Kluwer.
Woleński, J. (1998). Introduction. In K. Kijania-Placek & J. Woleński (Eds.), The Lvov-Warsaw School and Contemporary Philosophy (pp. 3-22). Springer. https://doi.org/10.1007/978-94-011-5108-5
Woleński, J., & Agassi, J. (2010). Łukasiewicz and Popper on Induction. History and Philosophy of Logic, 31(4), 381-388. https://doi.org/10.1080/01445340.2010.503388
Popper, K. (2002). The Logic of Scientific Discovery (J. Freed & L. Freed, Trans.). Routledge. (Original work published 1934).
Sinisi, V. F. (2004). Łukasiewicz on Reasoning in the Natural Sciences. Topoi, 23(2), 229-233. https://doi.org/10.1023/B:TOPO.0000048879.00003.43
Popper, K. (1983). Realism and the Aim of Science. W. W. Bartley III (Ed.). Routledge. (Original work published 1956).
Dating the exact time of priority is outside the scope of this work. However, the Stanford Encyclopedia of Philosophy states that Łukasiewicz’s “early formulation of the hypothetico-deductive method of science anticipates the ideas of Popper by more than two decades, though expressed less forcefully” (Simons, 2023, para. 14).
For more on the relationship between Popper and Łukasiewicz, see Woleński and Agassi (2010), Sinisi (2004), and Giedymin (1986).
As an introductory reference source on this, see Simons (2023).
I would like to extend special thanks to Professor Anna Brożek and Professor Jan Woleński for their respective brief email conversations that aided my research for this essay.
Fascinating. Thanks!