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Popper and Kuhn on Scientific Method

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© Josef Kala, December 2012

Popper and Kuhn on Scientific Method

Book Comparative Paper

Popper and Kuhn on Scientific Method
With the opening of the twentieth century came several contentious issues in the world of Western philosophy. With the rise of new and compelling tides in language, theory and critique, questions on the nature of science, epistemology and history came to the fore, causing tensions that needed ideological and methodological clarification and resolution. On one hand, the nineteenth century historicist philosophies of Hegel and Marx were taking active life in political and literary movements. On another, depth psychological theories in the wake of Freud were influencing everything from philosophy to thoughts on pedagogy. Then there was the staunch self-proclaimed empirical approach of the Logical Positivists who, alongside their ‘verificationist’ philosophy, sought to dismiss all metaphysics as meaningless garble, which helped to provoke contemporary movements in linguistic criticism like that of Wittgenstein and of Analytical Philosophy. All sides, incidentally, made proud claim to the young and prestigious watch word: ‘Science’. How such radically diverse outlooks and approaches could be made sense of in a coherent framework required a new and original breakthrough on how to evaluate knowledge and, specifically, what is science.

In 1934, that original work came from Karl Raimund Popper in the form of his monumental The Logic of Scientific Discovery – a book that would spark much debate and eventually give rise to a new academic disciplinary focus, the focus on ‘the philosophy of science’. In the Logic, Popper presented his structural critique that would disparage much of the aforementioned systems, as he contended for how he believed intellectuals should truly frame their approaches by offering what he said might be called “the one method of philosophy”¹ – a method that allows for and enables us to gauge progress. While philosophers are free to choose whichever operational method they want and works best for them, this is the method, he said, of “all rational discussion, and therefore of the natural sciences as well as of philosophy.”² The method, for which he would present a lucid and sound argument, is not of being merely analytical or empirical, but rather of simply stating one’s problem clearly and of examining its various proposed solutions critically. The remarkable scope yet fundamentally humbling assumptions underpinning this proposal would both clarify and challenge great and earnest minds on what it means to be ‘scientific’.

To sufficiently understand and appreciate Popper’s work, recognition of what he set out to do is essential. Popper’s thesis was one on epistemology and “The central problem of epistemology,” he said, “has always been and still is the problem of the growth of knowledge. And the growth of knowledge can be studied best by studying the growth of scientific knowledge.”³ He hence embarked on a thorough endeavor to comprehensively describe the process of scientific progress, with a definitive criterion to distinguish between the empirical sciences on the one hand, and logic and mathematics as well as metaphysical systems on the other – what Popper called “the problem of demarcation”.⁴ With his definitive criterion, any kind of theory or theoretical approach could be assessed for its scientific merits on an even plane.

The method of science, as presented in The Logic of Scientific Discovery is as follows: 1) Scientists encounter problems in the phenomena of the physical world, to which they hypothesize causes. 2) Sufficient and complimentary hypotheses are united in the construction of a tentative theory (purely metaphysical), which provides a framework through which the phenomena can be explained causally and which enables predictions on the nature and behavior of these phenomena in the physical world to be made – the accuracy and usefulness of these predictions giving the theory practical value; and the internal coherence of the theory making it legitimate. 3) The fundamental feature of these theories is that they are formed in such a way that they can be tested and refuted by observation of new facts (purely empirical) or problems which contradict the theory or its predictions – in which case a new theory is formulated, building on the last and allowing for more effective problem-solving and the accumulation of more knowledge through observation. This last feature is called the falsificationist principle, which is the defining feature of scientific theories and embodies Popper’s solution to the problem of demarcation. It will be noted from this description that scientific hypotheses and theories are always tentative and can never be ‘proven’ – as the Positivists would so much have liked. Science, says Popper, cannot prove, but at best only support or ‘corroborate’, a theory – whether it be gravitation or relativity or evolution – and any theory, to the extent that it is scientific, can with some observation or future discovery, be refuted or falsified. Conversely, any theory that is not framed in a way that can be tested and falsified – such as Marxism, historicism or Freud’s Oedipus Complex – is definitively unscientific.

Popper’s book remained a magisterial thesis that for a long time held full sway among commentators on science. But around the time of its second printing in 1959, American physicist and historian, Thomas Kuhn, was having trouble synthesizing his papers on the development of science from the ancient Greeks to our age with Popper’s strict methodological stance, as he prepared them for his students. Kuhn published his The Structure of Scientific Revolutions in 1962, in which he argued that science does not at all progress in uniform linear fashion according to some pre-justified ‘method’, but rather by a series of rare but necessary ‘revolutions’ which typically subvert our whole outlook on the world each time. Kuhn was strongly impressed by the subjectivism of the observations of scientists in any given age, molded by the general intellectual atmosphere and conventional framework, or ‘paradigm’, of their time. If Popper’s big contribution to theory of science was ‘falsificationism’, Kuhn’s was the concept of ‘paradigm shift’, whereby scientists’ theoretical network of orienting their observations and hypotheses is radically transformed with each new revolution in the field.

Kuhn’s description of the process of science as it actually happens is the following: 1) Scientists operate, theorize upon and observe nature according to an established paradigm. This he calls ‘Normal Science’. 2) Irreconcilable problems and observational mismatches with the established paradigm (what Kuhn called ‘Anomalies’), however, continue to build up and create tension with the existing intellectual state of affairs, until which time 3) there is a ‘Crisis’ or ‘Incommensurability’ phase, i.e., when the anomalies make it unfeasible to hold onto the established paradigm, which can no longer be sustained. 4) At this point a bold, original and intrepid individual sparks off a ‘Scientific Revolution’ with a new and ingenious perspective on the underpinning cosmology of contemporary science. 5) This creates a ‘Paradigm Shift’ within the scientific world, setting the ground for the development of 6) a new intellectual climate or Paradigm that will eventually mold future scientists’ observations and theories accordingly, allowing for Normal Science to resume and upon which the cycle may repeat itself. Paradigm shifts are rare and only called upon by crises that begin to prepare society for a destabilizing quake in its world view.

As an example of the above, Kuhn presents the Copernican Revolution, which he emphasized, did not during its origination offer more accurate predictions on celestial events, like planetary positions, than Ptolemy’s system. Rather, Copernicus’s model was adopted by cosmologists based on its appeal of offering a promise of simpler, better solutions in the future. Kuhn provided the following fundamental criticism to Popper’s falsificationism:
He [Popper] emphasizes the importance of falsification, i.e., of the test that, because its outcome is negative, necessitates the rejection of an established theory. Clearly the role thus attributed to falsification is much like the one this essay assigns to anomalous experiences… Nevertheless, anomalous experiences may not be identified with falsifying ones. Indeed, I doubt that the latter exist… no theory ever solves all the puzzles with which it is confronted at a given time; nor are the solutions already achieved often perfect. On the contrary, it is just the incompleteness and imperfection of the existing data-theory fit that, at any given time, define many of the puzzles that characterize normal science. If any and every failure to fit were ground for theory rejection, all theories ought to be rejected at all times.⁵

Two things are to be noted from this extract. First, as can be gleaned from the general tone of the rest of Kuhn’s book, is his apparent relativism. Kuhn doubts the existence of the falsificationist test that necessitates the rejection of an established theory, de-rooting the very basis of Popper’s foundation of science and substituting in its stead the idea of a shift in paradigms – a logically indeterminate procedure or transition from one mélange of scientific promise, enthusiasm and sociology to another. The second thing to note is that, in his ensuing commentary on why this should be so, Kuhn does not address Popper’s actual thesis, by suggesting a picture that digresses from the testability theory. Popper never claimed that a theory ever solves all the puzzles with which it is confronted or that its solutions are often perfect. Moreover, an incomplete or imperfect data-theory fit (which does indeed characterize normal science) is not, as Kuhn suggests is the case, a sufficient ground for theory rejection according to The Logic of Scientific Discovery – it is when data contradicts theory that Popper says the theory has been falsified.⁶ From the bio-chemist’s laboratory to the astronomer’s peering into distant orbits, testing with a mind to disprove the accepted theory is the daily activity of the scientist and Kuhn’s denial of the falsificationist foundation of The Logic is not supported as he does not address it directly in its purported frame.

Nonetheless, there is much to be said for The Structure of Scientific Revolutions. As the synopsis of its process of scientific development on the previous to last page suggests, Kuhn’s work is a sociological analysis on the history of science, as evolved and developed among human beings and cultures through time. It abstracts and theorizes on a general pattern that Kuhn’s extensive reading and breadth of cultural observation allowed him to infer. While this pattern is of great sociological interest and may be true in the history that The Structure covers, it 1) cannot be taken as a historical law of scientific progress, which was the very kind of enticement that misled the historicists of the Hegelian school, and 2) nor does it address the same specific question that The Logic of Scientific Discovery did; namely, what constitutes the epistemological basis of science as method, so as to define its merit and distinguish it from other epistemological methods? Merely saying that science has no such method as Popper proposes and then attempting, in its place, to induce an essential formula of scientific progress from historical pattern evades the question at hand and provides no deductive logical argument for support of such a claim.

In conclusion, Karl Popper’s notion of Falsifiability was truly a landmark contribution to the theory of science, which, alongside Empiricism, Naturalism and Skepticism, forms the foundational working assumptions of the scientific enterprise, in addition to offering great clarification and pellucid explication in epistemology and intellectual discourse – as was so desperately needed when The Logic of Scientific Discovery was first published. Thomas Kuhn’s The Structure of Scientific Revolutions, while describing engaging sociological and cultural models on the historical development of science, fails to logically attack this notion of Falsifiability on the epistemological plane as it purports to do. What Popper offered was a delineation of science when people follow its method, not a claim that its method was always followed in linear progression throughout history. For what cannot be denied of science, as of progressive rational discussion from Socrates onward, is that method counts for everything

¹ The Logic of Scientific Discovery, Popper, K., 1980, pg.16
² Ibid.
³ Ibid., pg. 15
⁴ Ibid., pg. 34
⁵ The Structure of Scientific Revolutions, Kuhn, T., 1970, pg. 146
⁶ The Logic of Scientific Discovery, Popper, K., 1980, pg.54


Popper, K.R. The Logic of Scientific Discovery, New York: Routledge, 1980. Print
Kuhn, T. The Structure of Scientific Revolutions, Chicago: The University of Chicago Press, 1970. Print