Popper’s Open Universe

Abstract

The thought of Karl Raimund Popper (1902–1994) is a phenomenon symptomatic of the twentieth century. It grew almost entirely out of the atmosphere which surrounded the empirical sciences. While Whitehead drew inspiration for his philosophy from the natural sciences and had the ambition to create a system in some sense consistent with the results of those sciences, it was not Popper’s intention in general to create any philosophical system at all and in particular it was not his intention to create a philosophy of nature. Popper from the beginning was interested in science, its methods, and its assumptions

Appendix: The Influence of Popper’s Thought on Contemporary Philosophy of Science

In contemporary philosophy of science the term “rationalism” is almost immediately identified with the views of Karl Raimund Popper. This is not surprising—Popper’s rationalism is consistent and is based on rigorous principles and its critical character keeps it free of many of the mistakes of earlier rationalist philosophies. Rejecting the dogmatic rationalism of his predecessors (especially the views of the logical empiricists of the Vienna Circle), Popper became the founder of critical rationalism. Its primary objective is a defense of rationality on the basis of epistemology and an elaboration of the methodology of the sciences which would be subordinated to the laws of logic without falling into contradictions, as had earlier inductionist methodologies. Our aim is not to provide a detailed analysis of Popperian philosophy of science, for there is already a large literature on that topic. It is necessary, however, to turn our attention to the great influence that Popper’s thought had on twentieth century philosophy of science. Popper initiated a new trend in epistemological research, in which problems of the development of scientific knowledge took first place. It is possible to say that he was interested not only in the internal logic of knowledge, as was the positivist tradition, but also in “science from the outside,” i.e., investigation of the principles which regulate the development of scientific knowledge. The Logic of Scientific Discovery, published in 1959, as well as Popper’s subsequent books presenting the ideas of critical rationalism, have provoked numerous controversies. It is worth having a look at the ideas to the origin of which Popper’s philosophy directly contributed.

Thomas Kuhn’s The Structure of Scientific Revolutions was written in large part as a reaction to the philosophy of Popper. Kuhn characterized his predecessor as a “permanent revolutionary.” He also said that, from the point of view of the history of science, Popper’s thesis cannot be accepted. The real development of science shows that it does not develop by the constant proposal of hypotheses and their refutation (“permanent revolutions”), as Popper had said. In Kuhn’s opinion, science develops in stages. Scientists accept a certain theory wanting to develop it as much as possible and to get as much as possible out of it. That state continues for a while; Kuhn calls this the period of normal science. One of the essential features of normal science is its institutionalization—publications, instruction in schools and universities, etc. Normal science is conservative and always develops within the framework of a certain paradigm or model which includes, among other things, fundamental theories; criteria of rationality; and metaphysical, epistemological, and methodological assumptions. Transition from one paradigm to another always has the character of a revolution and there is no logical continuity between paradigms. The coming of a revolution is presaged by the appearance of anomalies in normal science—phenomena which normal science cannot explain. After the revolution, the situation stabilizes and a new paradigm is formed. In the history of science—in Kuhn’s opinion—it is possible to distinguish four great scientific revolutions:

a:

Copernicus →Galileo → Newton →Einstein

Kuhn’s philosophy of science is a transition from Popper’s absolute rationalism to a situation in which attention is paid to the great influence of extra-scientific factors in science. For those paradigms are often something unconsciously present in the thought of scientists and establish the direction of research. One cannot translate between paradigms; they are incommensurable. Thereby, Kuhn breaks with the postulate of logical continuity in science. Science is not cumulative. Cumulative growth can occur only within the framework of a single paradigm, and agreement between paradigms is impossible, for they are governed by completely different conceptions of science.

Popper’s disciples reacted sharply to the criticism of their master and undertook a defense of rationalism in the philosophy of science. One of the defenders was Imre Lakatos. Lakatos’ rationalistic program, presented in his “Falsification and the Methodology of Scientific Research Programs,”²⁴ was not however a mere continuation of Popper’s thought. For Lakatos was aware that Popper’s “naïve” falsificationism contains many errors. The most fundamental of those errors, is the belief that scientists reject falsified theories. Lakatos, relying on research in the history of science, showed that in reality scientists try to improve falsified theories and do not reject them until they have found a better one. Lakatos called such falsificationism “sophisticated falsificationism.” His description of the development of science is also interesting. Science develops thanks to a sequence of theories, and that sequence is what he calls a research program. In such an approach, one can see a clear return to the idea of cumulativism in science (in contrast to Kuhn). The structure of a research program can be presented as follows:

The hard core, by methodological decision, is not subject to falsification. Here are found the fundamental claims of a given theory, and they cannot be changed. To the hard core also belong fundamental philosophical, metaphysical, and methodological assumptions (as in paradigms according to Kuhn) and the so-called positive and negative heuristics. The negative heuristic tells us what is not subject to falsification and the positive one—how to build auxiliary hypotheses and how to modify theories. A protective belt of auxiliary hypotheses is built in accordance with the positive heuristic and it can be changed.

In the twentieth-century philosophy of science, a controversy flared up between rationalism and trends which are—not always correctly—called irrationalistic. Critics of rationalism emphasized that there is no absolute criterion of rationality and science is not a purely logical construct, immune from all external influences. Of course it is hard to take seriously the extreme relativism postulated by, among others, the representatives of the Edinburgh school (David Bloor, Barry Barnes, Steven Shapin), who interpreted even the concept of truth by appeal to psychological and social causes. It is not, however, possible to disregard completely what was done in the philosophy of science after Popper. It is important to remember at least Popper’s student—Paul Feyerabend. Almost everywhere in his philosophy of science, one can find critical remarks about Popper. As one of the most important, but at the same time one of the most controversial, of Feyerabend’s achievements, one can cite the fact that, in arguing with the Popper’s logic of the development of science, he started a debate about the principles of the development of science. He put questions not only about the internal structure of science, but most of all about the social, economic, religious, and other factors which influenced science from the outside. He opposed what has been called internalism (of which Popper was a proponent), i.e., the requirement that science be cleansed of all extra-scientific influences, and subscribed to the externalist school. Externalists accept the occurrence of a close, irreducible connection between the content of science and its external determinants.