Karl Popper

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Karl Popper (1980)
Karl Popper, bust in the arcade courtyard of the University of Vienna

Sir Karl Raimund Popper CH FBA FRS (* July 28, 1902 in Vienna ; † September 17, 1994 in London ) was an Austrian - British philosopher who worked on epistemology , the philosophy of science , social and historical philosophy, and political philosophy the critical rationalism founded.


Popper is known for his rejection of the traditional positivist - inductivist view, according to which the scientific method is characterized by generalizations from observations to scientific theories. He turns the process around and admits the person making any claim (thesis) that would then have to be refuted methodically if it were not correct. He called the method the empirical falsification principle . According to this, scientific theories are merely uncertain speculations that try to overturn empirical science by searching for contradicting observations.

Popper is also known as an opponent of the classic approach in epistemology, according to an assumption on the basis of a statement of reasons must stand so that it is reasonable. Popper replaced it with the "first non-justification-oriented philosophy of criticism in the history of philosophy": The statement that an assertion lacks a justification should no longer suffice for it to be rejected, but there must be a logical contradiction to the facts . In the field of political philosophy, Popper is known for his theory of the open society , in which he criticized historicism and defended democracy .


childhood and education

Karl Popper was born on July 28, 1902, the son of lawyer Simon Siegmund Carl Popper and Jenny Popper , née Schiff , in Vienna . His parents were assimilated Jews who had converted to Protestantism . Simon Siegmund came from Prague , his father from Kolín , the birthplace of Josef Popper-Lynkeus . His mother's ancestors came from Silesia and Hungary . Many important personalities of the 19th and 20th centuries came from the Schiff family: scientists, doctors and musicians (such as the conductor Bruno Walter ). Popper grew up in a family home where books and music played an important role. As a child he was already interested in philosophical issues.

When Popper was twelve years old, the First World War began . The situation of the Jews in Vienna at that time was difficult. For one thing, they held important positions; Popper's wealthy father, for example, worked closely with the liberal mayor of the city, Raimund Grübl , who died in 1898 . On the other hand, ethnic and anti-Semitic prejudices and discrimination were commonplace.

In 1918, 16-year-old Popper left middle school prematurely and became a guest student at the University of Vienna. He attended lectures in mathematics , history, psychology , theoretical physics and philosophy. He only passed his Matura as an external specialist at the second attempt. The year before, he had failed in the subjects of Latin and logic . From 1920 to 1922 Popper was a student at the Vienna Conservatory, Church Music Department, but soon abandoned the plan to become a musician. During this time he earned his living as a laborer. In his decision to begin practical training, he had been influenced by his socialist friends, who were very political and saw themselves as future leaders of the working class. Disgusted by this, he made the temporary decision to become a worker himself. In parallel to his teacher training, he therefore completed an apprenticeship as a carpenter in 1924 with a journeyman's certificate.

Study and job

When Popper began his studies in the early 1920s, the political left dominated in Vienna . During this time (1918–1934) the city was also called Red Vienna . Popper was involved there - initially primarily interested in educational issues - in the socialist youth movement and in the Viennese school reform movement . At the same time he worked at Alfred Adler's individual psychological educational counseling centers in Vienna's working-class neighborhoods.

After the proclamation of the republic in November 1918, he joined the Communist Party and helped in the office of the party headquarters. The party undertook several overthrow attempts based on Lenin's example, then also under the guidance of Béla Kun . During an attempted coup on June 15, 1919, the leading Viennese communists were arrested by the police, whereupon the others started a demonstration at the police headquarters. Several thousand people tried to storm the Vienna police headquarters and free party members imprisoned there. The city security guard fired at a crowd of demonstrators in a side street, killing 20 people. Karl Popper later learned that the action was in fact part of a plan by cadres with ties to Béla Kun who wanted to come to power themselves through a coup. Assuming that class struggles would cause many more deaths if the revolution was not brought about quickly, they had no qualms about putting the lives of those involved in the liberation at risk. Popper saw himself deceived by the cadre and turned away from Marxism again.

In Vienna he met a. a. Ruth Fischer , Hanns Eisler , Paul Felix Lazarsfeld , Oskar Kokoschka , Adolf Loos , Arnold Schönberg and Rudolf Serkin .

Popper passed the exam at the teacher training institute in 1924 . However, because there was no vacant teaching position, he worked as an educator in a day care center for socially vulnerable children. From 1925 to 1927 he was a student at the Pedagogical Institute of the City of Vienna . His first publications come from this time ("On the position of the teacher towards school and pupil" 1925). They dealt with educational topics and appeared in Die Quelle and Schulreform . 1928 Popper was the psychologist and language theorist Karl Buhler with the thesis "The methods question the psychology of thinking" doctorate .

During his studies at Bühler, Popper got to know the psychology of Oswald Külpe and the “ Würzburg School ”. William W. Bartley claimed that this also had a decisive impact on his educational beliefs and later on his epistemology . However, Popper himself contradicted these claims. In 1929 he acquired the license to teach mathematics and physics for the secondary school.

In 1930 Popper got a job as a secondary school teacher in Vienna, which he held until 1935. In the same year he married his colleague Josefine Anna Henninger (1906–1985). 1930–1935 Popper lived with his wife in Vienna's 13th district at Anton-Langer-Gasse 46 in the Speising district ; there is a memorial plaque on the house.

The Vienna Circle

The fact that Karl Popper began to write down his philosophical thoughts was mainly due to his contacts with the Vienna Circle , the circle around Moritz Schlick , Rudolf Carnap and Otto Neurath . Schlick in particular distanced himself from Popper, who had criticized his neopositivist position, and accused him of uncontrollable behavior. In Popper's oral doctoral examination (Rigorosum) in 1928, Schlick was an assessor, which led to a dispute because, in Schlick's opinion, Popper was exaggeratedly critical of Ludwig Wittgenstein , who was valued by Schlick ; the latter wanted "like the Catholic Church to forbid the discussion of all questions to which he did not know the answer". Popper therefore received no invitations to the meetings of the circle.

Herbert Feigl suggested that he write, which Popper began after some hesitation. He spent three years working on a 1,000-page manuscript, only partially preserved today. The surviving parts finally appeared in 1934 as a considerably shortened version under the title Logic of Research , his epistemological and epistemological main work, in a series of publications by the Vienna Circle, although Popper criticized their positivism in it . This generous publication opportunity falsely earned him the reputation of a positivist, and his treatise was recognized by members of the Vienna Circle as a work that had arisen from their discussions. During this time he met Werner Heisenberg and Alfred Tarski . It was not until 1979 that another part of his original manuscript appeared under the title The two basic problems of epistemology .

Emigration to New Zealand and England

From 1935 to 1936 Popper traveled to England for a few months , where he met Erwin Schrödinger , Bertrand Russell and Ernst Gombrich . He had intensive discussions with Schrödinger and got to know Friedrich August von Hayek . At the Second International Congress for the Unity of Science (in Copenhagen in June 1936 ) he was deeply impressed by Niels Bohr , although he himself took a different interpretation of quantum mechanics . Especially the conversations with Alfred Tarski brought Popper to the insight how he could represent the correspondence theory of truth without problems.

The political situation in Austria became increasingly tense and Popper saw the "annexation" of Austria to National Socialist Germany coming. In this situation he accepted the offer of a lectureship at the University of Canterbury in Christchurch (New Zealand). In 1937 Popper and his wife quit their teaching positions and went into exile . Popper had to leave his family behind, the sick mother, sister, uncles, aunts and nieces. Sixteen family members were murdered in the Holocaust during the Nazi era .

Popper became a lecturer at Christchurch University. Although the college did not promote his research and demanded the teachers that all the teaching should pay, there emerged The Poverty of Historicism ( The Poverty of Historicism ) and the work that made him famous as a political thinker, The Open Society and Its Enemies ( The open society and its enemies ). In two volumes Popper analyzed in detail the totalitarian tendencies in the writings of Plato, Marx and Hegel. In addition, he dealt with the theory of probability .

In the winter of 1944/45 Popper received - mainly through the support of Friedrich von Hayek - the offer to teach at the London School of Economics and Political Science , which he accepted. At the beginning of January 1946 the couple arrived in London, where Popper began teaching as an associate professor. In 1949 he became a parallel professor of "logic and scientific methodology" at the University of London.

In 1961 Popper gave the opening lecture at a conference in Tübingen , the subject of which was the logic of the social sciences . Theodor W. Adorno gave the second lecture . The debate was then continued mainly in the Cologne journal for sociology and social psychology and was the beginning of the so-called " positivism dispute ". Within the German student movement , Popper, who had written his main epistemological work "Logic of Research" explicitly against positivism, was considered an "arch-positivist". The actual controversy between Popper's critical-rationalist position and the dialectic standpoint was mainly led by Hans Albert and Jürgen Habermas ; Popper was largely disinterested in this and wrote in a letter to Albert in 1970 that he “just couldn't take these people seriously”.

After retirement

Grave in the Lainzer Friedhof on Vienna's Küniglberg

In 1965 Popper was knighted by Queen Elizabeth II for his life's work as a Knight Bachelor . In 1969 he retired , but continued to publish steadily. He was a member of the economically liberal think tank Mont Pelerin Society founded by Hayek and the Royal Society (London). He was friends a. with the German Chancellor Helmut Schmidt . He was finally accepted into the Order of the Companions of Honor (CH) by Queen Elisabeth II . In 1973 he was awarded the Sonning Prize of the University of Copenhagen, in 1993 Popper received the Otto Hahn Peace Medal in Gold from the German Society for the United Nations (DGVN) in Berlin. The Council for Secular Humanism presented him with the Humanist Laureate Award.

Popper rarely spoke about religion. However, the so-called “lost interview” of 1969 is known about his views. Accordingly, he described himself as an agnostic and rejected what he believed to be arrogant atheism as well as the Jewish and Christian beliefs. However, he expressed respect for the moral teachings of both religions. Paul Feyerabend described him as a "straggler of the Enlightenment ".

His wife Josefine Anna Popper died in 1985 and was buried in Vienna at the Lainzer Friedhof in the 13th district in a grave of her family laid out in 1936 (group 2, no. 7). Karl Popper died on September 17, 1994 in East Croydon , London , after being seriously ill two weeks earlier. Up to this point he was still working on his work. Popper's body was cremated, his urn brought to Vienna and buried in his wife's grave on October 28, 1994. The grave was declared a grave of honor by the city administration and exists for the duration of the cemetery.

In 1998 the first project for the promotion of the gifted in Austria, the Sir Karl Popper School , which seeks to implement Popper's ideas for a better school, received approval to bear his name. The Karl Popper Collection of the University Library of Klagenfurt also bears his name. In 2010, in Vienna- Favoriten (10th district), Karl-Popper-Strasse near the new main train station was named after him; it is located in the immediate vicinity of the newly named traffic areas after Elias Canetti , Kurt Gödel and Alfred Adler .


Popper's work can be roughly divided into two phases: The first, which was characterized by the study of the methods of empirical science ; and the second, in which he dealt with metaphysical questions. According to William Warren Bartley, the boundary between the two can be set fairly precisely at November 15, 1960. Popper himself, however, always vehemently opposed a hermeneutical interpretation of these phases. He sees the main features of his thinking as drawn up in 1919 and from then on consistently uniform and without structural breaks, with only shifts in focus and occasional clarifications. The basic conception of Popper's philosophy is the rejection of the saying “nothing comes from nothing” and the insight that a system cannot guarantee its own existence, but can end it itself.

Philosophy of science

Popper presented his views on the philosophy of science comprehensively in his work Logic of Research , which first appeared in German in 1934 and was steadily expanded and improved in subsequent English and German editions (a few months before his death in 1994, Popper added a new appendix). He later carried it out further in The Two Basic Problems of Epistemology (which was written parallel to the Logic of Research , but was not published until 1978), The Quantum Theory and the Schism of Physics, and Objective Knowledge. An evolutionary design . In conjectures and refutations (English Conjectures and Refutations ) he applied the method as indicated in the title, also practically. Here he also described how he had developed his delimitation considerations since the 1920s, when he initially wanted to distinguish “ pseudoscience ” from “science”. As examples of pseudosciences, he named u. a. the psychoanalysis and Marxism , as an example of science Einstein's theory of relativity .

In the logic of research , Popper criticizes the view of logical positivism , which advocated the empirical method for the natural sciences. This method postulates the systematic collection of facts, which are formulated in logical protocol sentences. By means of induction , general laws of nature are inferred, either with the claim to security or at least to a high probability . Most philosophers of science would have advocated these views on the basis of Aristotle and Francis Bacon .

Popper, on the other hand, once again underlined David Hume's idea that, for reasons of formal logic, one cannot derive a general law from individual cases ( induction problem ), but only refute general propositions (“One cannot know more than one knows”). He also considers all attempts to derive at least quantifiable probabilities of theories from individual cases as misguided and provides mathematical and philosophical arguments to make clear the logical untenability of sentences such as "Theory A is true with 80% probability".

Instead, Popper suggests that theories (viewed abstractly) may be freely invented. In retrospect, experiments should then be carried out, the results of which are conventionally established as basic sets. The theories can then be refuted (falsified) through these basic sentences if the conclusions that are deduced from them are not confirmed in the experiment. In an evolutionary selection process , those theories that fail to refute prevail. By reversing the classic attempt to prove theories, Popper arrives at what at first glance appears to be counter-intuitive that scientists should try to refute their theories or to sift out theories with decisive experiments (cf. experimentum crucis ). By filtering out false theories, one gets closer and closer to the truth, but without ever being able to claim certainty or even probability. For the progress of the scientific and cognitive process, Popper considered both the creativity in setting up a theory and the critical attitude to it to be equally important in order to approach the truth in the long term.

However, he calls for consistency as the “highest axiomatic basic requirement” for theories, which every theoretical system - empirical or not - must meet, and states that “the objectivity of scientific propositions lies in the fact that they must be intersubjectively verifiable”, i.e. they must be falsifiable .

Popper emphasizes that the assumption that the world is structured according to law, or that there are laws of nature, is contained in the establishment of scientific theories - of course, like these theories themselves as a presumption, since it cannot be ruled out that all theories fail.

Metaphysical questions such as For example, he initially deliberately left open whether there is a real external world to which natural science refers with its theories and basic principles. He stressed that his approach was purely methodological and in no way had to presuppose metaphysical assumptions. However, even in the logic of research , he clearly distanced himself from the positivist position that such questions could not be formulated meaningfully at all, and rejected the corresponding attempts to formulate an empirical criterion of meaning. It was on this point in particular that Popper found himself in opposition to the neopositivists of the Vienna Circle and in particular the teachings of Ludwig Wittgenstein , with whom Popper only met once, in 1946 in Cambridge, where there was a violent clash (even if Popper himself was the legend that Wittgenstein is said to have threatened him there with a poker , referred to in his autobiography as a gross misunderstanding due to a joking remark).

Instead of looking for a criterion of meaning between empirical science and metaphysics, one should look for a criterion that delimits empirical science and metaphysics, which he believed to have found with its fundamental falsifiability: "An empirical-scientific system must be able to fail because of experience." Of course, he emphasized that metaphysical systems of thought recognize were genetically quite fruitful for science, even if they themselves could not be empirically tested. As an example he cites speculative atomism, which led to the development of the empirical-scientific atomic theory.

Later he came to the opinion that metaphysics could also be discussed rationally and, among other things, professed an ontological realism of the outside world, even if he admitted that the opposite position (i.e. idealism) cannot be strictly refuted. A strong “ indeterminism ” is also one of the most important components of Popper's later metaphysically supplemented worldview. He saw himself confirmed in this above all by quantum mechanics . Metaphorically, he maintained that so far, clouds had also been imagined as very complex clockworks; in fact, however, clockworks are only apparently very ordered clouds. He also transferred this indeterminism to social conditions ( the future is open ).

Social theory

Plato, GWF Hegel and Karl Marx (from left to right)

Poppers is in the public known work that in all the languages of the world (and, according to Popper unfortunately poorly into German) translated The Open Society and Its Enemies (German Open Society and Its Enemies ) in 1945. In it he expects detail with the systems of thought of Plato , Hegel and Marx , who, in his opinion, theoretically founded totalitarian systems and practically promoted them. As a positive counterpart to this "closed societies", he designed an "open society" that no plans on the drawing board, but is pluralistic in an ongoing process of improvement experiments and error corrections evolutionary should continue to develop. The term open society has entered political language and, according to Popper, originally came from Heinrich Heine .

Popper deals in particular with the works of Plato , the "greatest, deepest and most ingenious of all philosophers" and the "founder of the most important professional school of philosophy". The latter represented a conception of human life that was "repulsive and downright terrifying". His weakness was that, unlike Socrates, he believed in the "theory of the elites". In particular with his works Politeia ( The State ) and Nomoi ( The Laws ) he worked out and propagated the basic model of the totalitarian state . In doing so he also betrayed his teacher Socrates , who, as Popper wants to explain, would have been executed as a rebel in Plato's “ideal state”. Plato's rejection of Attic democracy and his preference for an authoritarian regime of so-called “ philosopher kings ”, who no longer have anything to do with the Socratic philosopher and are explicitly allowed to use lies propaganda, is what Popper tries to substantiate with many passages in the text. Plato was thus the first and most important theorist of a closed society in which there can be no non-violent change and where elites rule dictatorially . Popper saw in Plato "the first great political ideologue who thought in terms of classes and races and suggested concentration camps."

Plato is also a propagandist of the society's theory of decline , according to which society was originally in a “good” (closed) state of nature and every opening, liberalization and emancipation or critical questioning of traditions are signs of decadence , degeneration and decay. This doctrine (" Myth of the Horde") has become an important part of the propaganda of many dictatorships and authoritarian-conservatist ideologies; the influence z. B. in Oswald Spengler's " The Downfall of the Occident ".

Popper also writes that Plato "invented the middle schools and universities" by devising the basic principle of the modern "devastating" educational system.

Popper criticizes Aristotle in a similar but less extensive manner . He admits that Plato and Aristotle did a great philosophical work with ideas that were original and significant for their time and were of paramount importance for Western philosophy and science. But "great philosophers make great mistakes" and it is necessary to identify and criticize the totalitarian and anti-human tendencies in their works.

The second part of the work is aimed at the criticism of the "oracular philosophers" of the 19th century, in particular Georg Wilhelm Friedrich Hegel and Karl Marx . In Hegel, as in the other representatives of German idealism , Popper sees primarily a charlatan and deceiver, and secondly a reactionary apologist of the Prussian state power, whose philosophy also favored totalitarian systems. Popper raises the charge of charlatanry v. a. with reference to the dialectical methods of Hegelian philosophy. These are, insofar as they are at all understandable, postulated solely in order to undo the rules of logic and especially to be able to glorify authoritarian Prussia as the highest realization of freedom. Hegel was an official state philosopher who courted the existing state power with his legal and power positivism ("What is real is reasonable"). According to Popper, a larger part of the Hegelian writings was formulated in an intentionally incomprehensible manner in order to make criticism impossible. With this attempt to simulate a lack of substantive substance through incomprehensible language, Hegel ushered in a new era in the history of philosophy that was not geared towards the exchange of ideas and argumentation, but rather towards impressing and intimidating. This 'jargon' initially led to intellectual and then moral irresponsibility. Popper also tries to show connections between this thinking and centralism , statism and nationalism and fascism . He sees the intellectual historical roots of the latter primarily in a combination of Hegelian philosophy of history with the neo-Malthusian biologisms of the late 19th century, especially those of Ernst Haeckel . Popper brings the philosophical foundation of the fascist ideologies of the 20th century to the formula "Hegel plus Haeckel".

Popper later also sharply criticized contemporary social Darwinism, which would sometimes disguise itself as sociobiology .

Marx, which is also extensively criticized in the second volume of the Open Society , comes off a little better. Popper credits him with an honest sympathy for the suffering of the socially disadvantaged and a genuine interest in an improvement or humanization of the world (in a comment added later (1965), however, he relativized this opinion with reference to Leopold Schwarzschild's book "Der Rote Preuße": Marx was apparently "far less human and freedom-loving" than he assumed). Popper also describes Marx as an important economist and sociologist and admits that Marx did not rule out that the road to communism could also be reached in a non- revolutionary way. He also distinguishes it sharply from later vulgar Marxist flattenings, which were mostly associated with "naive" intentionalist conspiracy theories. However, he vehemently criticizes Marx's dialectical method adopted by Hegel and his deterministic view of history, which ultimately also leads to a closed world view. Large parts of the Marxist theory of capitalism are also wrong.

The publication in 1945 served as a political signal. It attacks closed thought structures and ideological constructions. Although neither National Socialism nor Stalinist socialism are mentioned explicitly, it is clear that the criticism is directed against them. Popper outlines the model of an open and pluralistic society in which progress slowly sets in.

Another work from this topic is What is Dialectic? , in which Popper criticizes the Marxian and Hegelian dialectics with the terms of formal logic. The 1957 published The Poverty of Historicism ( The misery of historicism ) attacks again primarily Marx and Hegel because of their methodology. In historicism , by which Popper understands the belief that history proceeds according to law and that societies can be planned, Popper sees a basic evil in social theory.

Positivism dispute

With his fundamental discussion on the "logic of the social sciences" at the Tübingen working conference in 1961, Popper sparked the so-called positivism dispute in German sociology. He and Hans Albert , who advocated the unity of the method of natural and social sciences based on critical rationalism , were contradicted there by the dialecticians of the Frankfurt School , Theodor W. Adorno and Jürgen Habermas , and positivism was attested. Ralf Dahrendorf was looking for a middle ground .

After his initial contribution, Popper no longer took part in the discussion, which was continued in his place by Hans Albert, since he saw no basis for understanding with Adorno and Habermas. In this context, a letter by Popper, which - without his consent - was published in the weekly newspaper Die Zeit under the title “Against the big words” (1971, ZEIT No. 39, page 8), has also become known. This article was later reprinted in In Search of a Better World in the chapter Against Big Words . Popper criticizes the language of Adorno and Habermas as obscurantism , which he had already accused Hegel of in his work The Open Society and Its Enemies . In order to substantiate this claim, he “translated” concise parts of texts that Adorno and Habermas had written in the context of the positivism dispute into a language that was easy to understand. In Popper's opinion, these were not only written with the aspect of easy comprehension and criticism in mind, but possibly even with the exact opposite intention: According to Popper, big words could also serve to formulate intellectually modest content so incomprehensibly that a criticism deliberately made difficult or prevented. He wrote:

“From my socialist youth, I saved many ideas and ideals into old age. In particular: every intellectual has a very special responsibility. He had the privilege and opportunity to study; in return he owes it to his fellow human beings (or "society") to present the results of his studies in the simplest, clearest and most understandable form. The worst - the sin against the Holy Spirit - is when the intellectuals try to pose as great prophets to their fellow men and to impress them with oracular philosophies. If you can't say it simply and clearly, you should keep silent and continue working until you can say it clearly. [...] What I called above (point 1) the sin against the Holy Spirit - the presumptuousness of the three-quarters educated - that is the thrashing of phrases, the pretending of a wisdom that we do not have. The recipe is: tautologies and trivialities seasoned with paradoxical nonsense. Another recipe for cooking is: write gurgle that is difficult to understand and add trivialities from time to time. That tastes good to the reader, who is flattered to find thoughts in such a 'deep' book that he himself has already thought. "

However, in Popper's view, every theory and every scientific position should be formulated in such a way that criticism is as easy as possible. His criticism of "obscurantism" is only one aspect of Popper's more comprehensive criticism of what he calls "professionalism". He opposed “professional ethics,” an unspoken gentlemen's agreement that prescribes that university professors should protect one another's authority. He countered this with the demand for intellectual modesty.

Popper coined the term liberal razor based on Ockham's razor , and he described himself as a “non-revolutionary liberal ”.

Three worlds theory

In the philosophy of mind, Popper turned against both the classical mind-body dualism and reductionist theories such as behaviorism . On the other hand, he proposed a conceptual division of the world into three areas, namely:

  • World 1, that is the physical world
  • World 2, the world of individual perception and consciousness
  • World 3, the world of intellectual and cultural contents that can exist independently of the individual consciousness, e.g. B. the contents of books, theories and ideas.

Popper argued that all three worlds were real, since causal interactions could be observed, with world 2 acting as an intermediary between world 3 and world 1. An example is the building plan of a house (world 3: a model in a drawing language of the building industry), which is understood by a person (world 2: consciousness of the builder) and then implemented in a concrete house (world 1: physical object ). The house belongs in world 1 and world 3 at the same time.

According to Popper, the classic dual separation has ignored the difference between an experience of consciousness and, for example, the logical content of a theory. Both are undifferentiated and assigned to the mental.

Popper argued that world 3 should initially be considered a product of man (in contrast to Plato and Hegel's ideas, for example), but still ascribing independence and objectivity to it. His own example is the purely human invention of numbers (in contrast to Leopold Kronecker ): The occurrence of prime numbers and mathematical prime number problems then already take place “unplanned” and without the need for human intervention. Thus, for example, the prime numbers, problems, hypotheses, theories, ideologies and other inhabitants of the world 3 have a reality that exists without us humans, just as the existence of Mount Everest precedes its discovery .

A similar division into three worlds can be found in classical Greece as logos, psyche and physis, with the Romans as ratio, intellectus and materia, and last but not least with Kant as reason, understanding and the outside world.

Reception and criticism

Although Popper's critical rationalism found many supporters and sympathizers among high-ranking scientists early on (mainly physicists, including Albert Einstein , but also Nobel Prize winners from other disciplines, namely Peter Brian Medawar , John Carew Eccles and Jacques Monod ), he was neither in the theory of science nor in to enforce decisively in scientific practice. In both areas there are still inductivist-empiricalist confirmatory positions, today commonly associated with Bayesian probability theories of induction, which, however, are often rephrased in Popper's terminology.

But Popper's ideas were also criticized by philosophers who rejected empiricism and inductivism themselves, especially through the positions of Thomas S. Kuhn . According to Kuhn, Popper's philosophy of science does not stand up to a test by the history of science; Counterexamples or “anomalies” did not in any way result in the revocation of the theory or the paradigm, but rather to be integrated through auxiliary hypotheses. Only when there is a strong accumulation of anomalies does a “crisis” arise, which then leads to a “scientific revolution” replacing the old paradigm, including key terms. According to Popper, it is precisely in this approach that the mistake of reasoning lies; The philosophy of science is not an empirical-scientific theory (like Einstein's theory of relativity) and therefore cannot be tested on the basis of the actual course of science, but in turn provides the standards for assessing its rationality.

Wolfgang Stegmüller tried to formulate Kuhn's position in a more rationalistic way. Imre Lakatos tried to develop a mediating position between Popper and Kuhn that would preserve the strengths of both approaches. Paul Feyerabend, on the other hand, went even further than Kuhn and even doubted the usefulness of a subject such as the theory of science ( anything goes ).

Popper's ideas were also controversial in the field of social sciences (see section Positivism Controversy ). At times a "Popper school of thought" of followers was formed, which mostly consisted of Popper students.

In terms of philosophy of science, Popper was accused of postmodern irrationalism and total skepticism by David Stove and Martin Gardner , who represent empiricalist positions, and of "naive" falsificationism by followers of Kuhn and Lakato, and dogmatic adherence to the priority of observation in the social sciences and humanities.

The normative aspects of Popper's social theory have been judging the left since the "positivism controversy" predominantly as neoliberal , while economic liberals classify him as a socialist. Politically, Popper can initially be classified as a radical socialist, later as a moderate socialist and finally - especially under Hayek's influence - as a moderate liberal. Despite his membership in the Mont Pelerin Society, however, in the opinion of Gebhard Kirchgässner , he differed decisively from the neoliberal market ideology that is represented by this society today.

Between Poppers Fallibilism and the Austrian School of Economics, as it u. a. As represented by Hayek, there are fundamental methodological differences: According to Popper, there is no science without empirical testing of potentially fallible theses and theories. Disciplines that do not accept this practice immunization and are therefore dubious. The Austrian School differs from all other economic schools u. a. in that it works purely logically. At best, empiricism serves as an illustration of the theses recognized a priori. Contradicting research results never indicate errors in the theory, but generally only indicate errors in the course of the investigation.

Popper's criticism of Plato, Hegel and Marx was also contradicted, sometimes vehemently, by the philosopher Ronald B. Levinson , Walter Kaufmann and Maurice Cornforth. Levinson criticized Popper's view of Plato in his 1953 book In Defense of Plato . According to this, Popper is often only concerned with spreading his own political ideas. Popper reinterprets Plato's writings into a totalitarian work, especially Popper's own translations from ancient Greek are tendentious and falsified. Popper opposed this criticism in a note that has been appended to the requirements of the Open Society since 1961 .

Charles Taylor attested Popper to have attacked more important philosophers (especially Plato and Hegel) with the attitude of a pop star and to have thereby demanded an attention that did not correspond to the meaning of his thoughts in any way.

The widespread type of reception was subjected to harsh criticism from supporters of Popper, ranging from the accusation that Popper was incompetently falsified, misquoted or unread even by professional philosophers, to the assertion that the majority evade the admission that Popper by silence I have really and definitively solved some fundamental philosophical problems, thereby exposing ideas as nonsense, which are still presumed uncritically today in the western world almost without exception. William Warren Bartley found harsh words during Popper's lifetime:

“Sir Karl Popper is not really a participant in the contemporary professional philosophical dialogue; quite the contrary, he has ruined that dialogue. If he is on the right track, then the majority of professional philosophers the world over have wasted or are wasting their intellectual careers. The gulf between Popper's way of doing philosophy and that of the bulk of contemporary professional philosophers is as great as that between astronomy and astrology. "

“Sir Karl Popper does not actually take part in the dialogue of contemporary professional philosophy; on the contrary: he took this dialogue to absurdity. If he is correct, the majority of professional philosophers around the world have wasted, or are about to, squandering their intellectual careers. Popper's way of practicing philosophy is to the approach of most contemporary professional philosophers much the same as astronomy is to astrology. "

- William Warren Bartley

A more detailed and explicit attack that Bartley directed against the falsification operated by experts and thus become the authoritative interpretation of Popper had to be pulped (in English print) and censored (in American print) because Bartley explicitly spoke of "incompetence" and thereby Named, whereupon one of the authorities concerned threatened legal action.

Rafe Champion was similarly clear:

“Popper's ideas have failed to convince the majority of professional philosophers because his theory of conjectural knowledge does not even pretend to provide positively justified foundations of belief. Nobody else does better, but they keep trying, like chemists still in search of the Philosopher's Stone or physicists trying to build perpetual motion machines. "

“Popper's ideas could not convince the majority of professional philosophers, because his theory of guesswork does not even try to create the impression that it offers positively justified bases for beliefs. Nobody else does it better, but they keep trying, like chemists who are still looking for the philosopher's stone or physicists who are trying to build a perpetual motion machine . "

- Rafe Champion

In summary, David Miller claimed at the 2007 Popper Congress:

“What distinguishes science from all other human endeavors is that the accounts of the world that our best, mature sciences deliver are strongly supported by evidence and this evidence gives us the strongest reason to believe them. ' That anyway is what is said at the beginning of the advertisement for a recent conference on induction at a celebrated seat of learning in the UK. It shows how much critical rationalists still have to do to make known the message of Logic der Research concerning what empirical evidence is able to do and what it does […] [critical rationalists] are rightly proud of having the only house in the neighborhood that is logically watertight [although] we must inevitably be aware that not everything inside is in impeccable order. "

"Science differs from all other human activities in that the worldview that our best and most advanced sciences give us is strongly supported by evidence and that this evidence gives us the strongest reasons to believe in this worldview." Or so it is in the announcement of a conference on induction recently held at a famous British teaching institution. It shows how long the road still lies ahead of the adherents of critical rationalism before the message of the logic of research is proclaimed, especially with regard to the question of which function empirical evidence fulfills or can fulfill at all. [Supporters of Critical Rationalism] are rightly proud to be the only ones in their field to be able to present a logically watertight conceptual structure, even if we must of course be aware that not everything inside is in perfect order. "

- David Miller

Hans Albert accused the post-positivist, analytical-Anglo-Saxon philosophy of having circumvented a confrontation with Popper mainly by silence or by taking over his positions in a hidden way (which were often passed off as ideas of his own). Accordingly, Popper's influence and reputation today are v. a. in the natural sciences and economics considerably larger than in specialist philosophy.



  • William Warren Bartley was Popper's favorite student, although the two were at odds for many years. Bartley published Popper's important postscripts on the logic of research in 1982/83 (three volumes, German 2001/2002 by Eva Schiffer and HJ Niemann). His work is best known: Escape into engagement .
  • Imre Lakatos - Hungarian-English mathematician , logician, physicist and philosophy of science . He was first a communist politician in Hungary, then an opponent of the system then ruling; he studied with Popper in London in the 1950s. Applied critical rationalism to mathematics (justification problem of mathematics).
  • Thomas S. Kuhn studied with Popper when he was giving lectures in the USA. The result was one of the most powerful books on the theory of science in the last few decades: The Structure of Scientific Revolutions , in which, however, he took a contrary position to Popper's theory of science.
  • Paul Feyerabend was an Austrian philosopher and scientific theorist, a direct student of Popper, who later opposed Popper with his opposition to the compulsory method . With the slogan “Anything Goes!” He countered Popper's uniform method.
  • George Soros , 1954 at the London School of Economics, finance broker and billionaire whose 'Open Society Project' seeks to consolidate structures based on the rule of law in Eastern Europe.
  • Hubert Kiesewetter , an economic historian emeritus in Eichstätt, studied with Popper in the 1960s and was his friend in Popper's last years. His book Von Hegel zu Hitler is well known .
  • David William Miller was a close associate of Popper for thirty years. Miller is regarded in the Anglo-Saxon countries as the authority for questions of critical rationalism.
  • John WN Watkins was an officer in the Royal Navy, then a student and finally Popper's successor to his chair at the London School of Economics (LSE).
  • Joseph Agassi studied physics and was research assistant at Popper from 1953 to 1960.
  • Alan Musgrave was with Popper at the LSE from 1958 to 1970.
  • Other collaborators were Ian C. Jarvie , John Worrall and Jeremy Shearmur .

Friends and admirers

  • Hans Albert is a German philosopher, scientific theorist and social scientist. He was the first to widely disseminate Popper's philosophy in Germany as part of critical rationalism .
  • Friedrich August von Hayek , Nobel Prize Winner for Economics and Business Philosopher. Popper and Hayek were friends. Hayek was a supporter of Popper's philosophy of science.
  • Victor Kraft, the Austrian theorist of science, philosopher and state librarian, Karl Popper himself wrote in the book The Two Basic Problems of Epistemology, which was first published in 1979 (the manuscript was written in the 1930s, 4 years after Kraft's death) : “Strength takes - as far as I can can judge - in advance the basic ideas of the deductivist-empirical standpoint represented by me ”.
  • Helmut F. Spinner developed fallibilism in the direction of theoretical pluralism .
  • Ernst Gombrich (1909–2001), an important art historian , often refers to Popper and for the first time writes history in Popper's sense consciously as problem history.
  • Peter Brian Medawar (1915–1987), 1960 Nobel Prize winner for medicine, repeatedly referred to Popper.
  • Hermann Bondi (1919–2005), mathematician and cosmologist ( steady state theory of the universe), consistently followed Popper's philosophy.
  • Ralf Dahrendorf (1929–2009) was influenced by Popper's philosophy.
  • Helmut Reinalter teaches at the University of Innsbruck.
  • Helmut Schmidt (1918–2015), former German Chancellor, was a friend and admirer of Popper.
  • Hartmut Esser , German sociologist, representative of Popper's philosophy of science.
  • Gerhard Vollmer , German biologist and philosopher, developed the evolutionary epistemology of Konrad Lorenz in line with Popper's epistemology
  • Alfred Herrhausen (1930–1989), CEO of Deutsche Bank, was a friend and supporter of Popper.
  • Gunnar Andersson , Swedish philosopher, defended Popper's positions against the criticisms of Kuhn, Lakatos and Feyerabend ( Critique and History of Science: Kuhn's, Lakatos' and Feyerabend's Critique of Critical Rationalism ).
  • Hans-Joachim Niemann , German philosopher, many writings on Popper and Critical Rationalism (including a lexicon of Critical Rationalism ). Analyzes ethics and morals in the context of critical rationalism ( strategy of reason ).
  • Reinhold Zippelius , German lawyer, developed his legal philosophy according to the method of critical rationalism (see d.).
  • Franz Austeda (1923–2009), Austrian philosopher and educator, was a personal friend with whom he met regularly.


Awards, medals and prizes

Popper received the following awards, medals and prizes:

Honorary doctorates

Popper received the following honorary doctorates:

  • 1962: Hon. LL.D., Chicago
  • 1966: Hon. LL.D., Denver
  • 1971: Hon. Lit.D., Warwick
  • 1973: Hon. Lit.D., Canterbury (NZ)
  • 1976: Hon. D. Litt., Salford
  • 1976: Hon. D. Litt., The City University
  • 1978: Dr.rer.nat.hc, Vienna
  • 1978: Renewal of the Dr. phil from 1928 by the Philosophical Faculty of the University of Vienna
  • 1978: Dr.phil.hc, Mannheim
  • 1978: Hon. D. Litt., Guelph
  • 1979: Dr.rer.pol.hc, Frankfurt am Main
  • 1979: Dr.phil.hc, Salzburg
  • 1980: Hon. Litt.D., Cambridge
  • 1981: Hon. D.Sc., Gustavus Adolphus College
  • 1982: Hon. D.Litt., Oxford
  • 1986: Hon. D.Sc., London
  • 1991: Dr.phil.hc, Catholic University of Eichstätt
  • 1991: Dr.phil.hc, Madrid
  • 1993: Dr.phil.hc, Athens
  • 1994: Dr.med.sc.hc, Charles University

Memorial plaques

  • Residential building in Vienna, Anton-Langer-Gasse 46
  • Library of the Carpenters' Guild, Vienna, Ziegelofengasse 31


  • 1925–1935 (published together in 2006): Early Writings . Contains 'habit' and 'experience of the law' in education (final thesis), on the question of method in thought psychology (dissertation) and axioms, definitions and postulates of geometry (qualification document for the teaching profession) as well as several articles
  • 1930–1933 (published in parts in 1979; previously circulated as a manuscript): The two basic problems of epistemology
  • 1934: Logic of Research. On the epistemology of modern natural science . 11th edition 2005, ISBN 3-16-148410-X
  • 1936 (presented at a private meeting; published 1944/45, as a book in 1957): Das Elend des Historizismus , ISBN 3-16-148025-2
  • 1945: The open society and its enemies (2 volumes) ISBN 3-16-148068-6 and ISBN 3-16-148069-4
  • 1956/57 (published 1982; previously circulating as galley proofs): The quantum theory and the schism of physics (from the postscript on the logic of research III)
  • 1956/57 (published 1982; previously circulating as galley proofs): The open universe (from the postscript on the logic of research II)
  • 1956/57 (published 1983; previously circulating as galley proofs): Realism and the goal of science (from the postscript on the logic of research I)
  • 1963: Conjectures and Refutations , ISBN 3-16-147311-6
  • 1973: Objective Knowledge , ISBN 3-455-10306-5
  • 1976: starting points. My Intellectual Development , ISBN 3-455-08982-8
  • 1977: The I and its Brain , (together with John C. Eccles ) ISBN 3-492-21096-1
  • 1984: In Search of a Better World , ISBN 3-492-20699-9
  • 1985: The future is open (together with Konrad Lorenz )
  • 1990: A world of propensities
  • 1991: I know that I know nothing - and hardly that (interviews with Professor Albert Menne, Günther Zehm and Manfred Schell) ISBN 3-548-34833-5
  • 1992: The Lesson of this Century
  • 1994: All life is problem solving , ISBN 3-492-22300-1
  • 1994: The myth of the frame
  • 1994: Knowledge and the mind-body problem
  • 1998: The World of Parmenides , German: Die Welt des Parmenides, the origin of European thought (translated by Sibylle Wieland and Dieter Dunkel, edited by Arne F. Petersen and Jørgen Mejer). Piper, Munich 2001, ISBN 3-492-04205-8 .
  • 2002: All people are philosophers


  • "Philosophy against False Prophets" (HR, August 7, 1974). Interview with Tomas Rotstein, approx. 45 minutes
  • “Tolerance and intellectual responsibility” (SR, March 16, 1982). Lecture, approx. 40 minutes
  • “The myth of the inescapable” (BR, July 27, 1982). Lecture, approx. 50 minutes
  • “Open Society - Open Science” (HR, July 17, 1984). Interview with Tomas Rotstein, approx. 30 minutes
  • “One should not believe that one can live without risk” (July 4, 1987). Conversation with Volker Friedrich, about an hour
  • “The principle of criticism in the open society” (BR, July 30, 1992). Conversation on the occasion of his 90th birthday with Willy Hochkeppel , approx. 55 minutes


To work and life

  • Florian Russi : Karl Popper - The Critical Rationalist . Mitteldeutscher Verlag, Halle 2020, ISBN 978-3-96311-366-6 .
  • Martin Morgenstern and Robert Zimmer : Karl Popper . Deutscher Taschenbuch-Verlag, Munich 2002. ISBN 3-423-31060-X . Very well prepared didactically with images and text boxes.
  • Jürgen August Alt : Karl R. Popper. Campus 1992 series, ISBN 3-593-34716-4 , new 2001: ISBN 3-593-36834-X . Short and excellent introduction.
  • Manfred Geier : Karl Popper. rororo monograph, Reinbek 1994; ISBN 3-499-50468-5 . Well written; biographical details; Analysis of the work; enriched with many pictures and quotes; therefore very memorable.
  • Peter Schroeder-Heister:  Popper, Sir Karl Raimund. In: New German Biography (NDB). Volume 20, Duncker & Humblot, Berlin 2001, ISBN 3-428-00201-6 , pp. 625-628 ( digitized version ).
  • Eberhard Döring: Karl R. Popper - Introduction to life and work. Hoffmann and Campe 1987, ISBN 3-455-08626-8 .
  • Lothar Schäfer: Karl R. Popper. Becksche series - great thinkers, 1988, ISBN 3-406-33215-3 .
  • Hubert Kiesewetter , (Ed.) / Helmut Zenz: Karl Poppers Contributions to Ethics. Mohr Siebeck Verlag, Tübingen 2002, ISBN 3-16-147773-1 .
  • Wilhelm Baum, Kay E. Gonzalez: Karl R. Popper. Morgenbuch-Verlag, Berlin 1994, ISBN 3-371-00393-0 .
  • Maurice Cornforth , The open philosophy and the open society . 2nd, rev. ed., Lawrence & Wishart, London 1977. The classic criticism from the left spectrum.
  • David J. Edmonds, John A. Eidinow: How Ludwig Wittgenstein threatened Karl Popper with the poker : an investigation . DVA, Munich 2002, ISBN 3-421-05356-1 (corr. Edition: Fischer TB, ISBN 3-596-15402-2 , 2003, 2nd edition 2005). Treating their clash in Cambridge in 1946 is also an easily understandable account of their philosophical and biographical differences, particularly with regard to the Vienna years and their Jewish origins. Also in Engl. (= Orig.) And Span. (2001).
  • Franz M. Wuketits : Where is the “liberal razor”? In: Enlightenment and Criticism 1/1998, p. 34 ff.
  • Manfred Lube: Karl R. Popper - The library of the philosopher as a mirror of his life . Imprimatur. A yearbook for book lovers. tape 18 , 2003, ISBN 3-447-04723-2 , pp. 207–238 ( Online ( Memento from February 27, 2008 in the Internet Archive ) [PDF; 550 kB ]).
  • Manfred Lube: Karl R. Popper. Bibliography 1925–2004: philosophy of science, social philosophy, logic, probability theory, natural sciences . Peter Lang, Frankfurt / Main etc. 2005. (=  series of publications by the Karl Popper Foundation Klagenfurt. ) ISBN 978-3-631-53450-2 ; Online version: ub.uni-klu.ac.at
  • Nasher, Jack : The state theory of Karl Poppers. A critical-rational method. Mohr Siebeck, Tübingen 2017, ISBN 978-3-16-155243-4 .
  • Dagmar Niemann (translator): The Paths of Truth ( Memento from February 15, 2009 in the Internet Archive ). Enlightenment and Criticism (2/1994), p. 38 ff.
  • William W. Bartley: A Difficult Man. A portrait sketch by Sir Karl Popper. In: Eckhard Nordhofen (ed.): Philosophers of the 20th century. Athenaeum, Königstein / Ts. 1980, ISBN 3-434-46071-3 .
  • John WN Watkins: Karl Raimund Popper 1902-1994. (PDF; 267 kB) In: Proceedings of the British Academy. No. 94, 1997, pp. 645-684.
  • Hans Albert: Karl Popper (1902-1994) . In: Journal for General Philosophy of Science. No. 26, 1995, pp. 207-225.
  • Volker Gadenne: Progress towards deeper problems . In: Protosociology. No. 7, 1995, pp. 272-281, ISSN  0940-4147 .
  • David Miller: Sir Karl Raimund Popper, CH, FBA 28 July 1902–17 September 1994. In: Biographical Memoirs of Fellows of the Royal Society. No. 43, Nov. 1997. pp. 368-409.
  • Friedrich Stadler : "Documentation: Popper and the Vienna Circle - From a conversation with Sir Karl Popper", in: ders., Studies on the Vienna Circle , Frankfurt am Main: Suhrkamp 1997, 525-545.
  • Harald Stelzer: Karl Popper's social philosophy. Political and Ethical Implications . Lit-Verlag, Vienna 2004.
  • Harald Stelzer: Karl Raimund Popper and critical rationalism read interculturally . Traugott Bautz, Nordhausen 2007. (=  Intercultural Library. Volume 128)
  • Hans-Joachim Niemann : 70 years of falsification: royal road or dead end? In: Enlightenment and Criticism. No. 2, 2005, pp. 52-79 ( PDF (102 kB )).
  • Edgar Morscher (Ed.): What we owe to Karl R. Popper and his philosophy. For his 100th birthday . Academia Verlag, Sankt Augustin 2002. Contains treatises on Popper's theory of probability and logic, on his science and epistemology, on his ontology, practical philosophy and aesthetics; Also contains personal memories of Popper and letters to and from Popper.

Study Guide

  • Herbert Keuth : The philosophy of Karl Poppers . 2. corr. Edition, Mohr-Siebeck, Tübingen 2011, ISBN 978-3-16-150660-4 , This is the currently relevant study guide, which scientifically analyzes and comments on the entire work, in a depth that goes far beyond the work biographies mentioned above . The text leads to all important sources. Many problematic pop theses are being prepared for further research. The book is aimed at readers who want to understand Popper thoroughly or who want to do their own research in this area.
  • Herbert Keuth (Hrsg.): Karl Popper: Logic of Research (=  classics interpreting ; Vol. 12). 4th, edited edition, Akademie Verlag, Berlin 2013, ISBN 978-3-05-005708-8 .
  • Hans-Joachim Niemann : Lexicon of Critical Rationalism . Mohr Siebeck, Tübingen 2004, ISBN 3-16-148395-2 ; paperback 2006. For quick information on the thousand most important terms and arguments of Popper's (and Hans Alberts ) critical rationalism. With numerous cross-references and references to the original text passages.
  • Ingo Pies , Martin Leschke (ed.): Karl Poppers Critical Rationalism . Mohr-Siebeck, Tübingen 1999.

English-language biographies

  • Malachi Haim Hacohen: Karl Popper - the Formative Years 1902-1945. Politics and Philosophy in Interwar Vienna . University Press, Cambridge 2000, ISBN 0-521-47053-6 . The relevant Popper biography up to 1945, which throws a lot of light on Popper's work and exposes his spiritual roots. This author has not planned a sequel (Popper lived for another 49 years).
  • Bryan Magee: Popper . Fontana paperback, 1973, with many later editions. Very short and very good. Magee was an active politician and a friend of Popper. Even more intimate insights into Popper's (intellectual) life can be found in the same author's Confessions of a Philosopher , Random House hardcover 1997, chapter 11 (German: Confessions of a Philosophen. 2nd edition, Econ Ullstein List Verlag, Munich 2001, chapter 11) .
  • Joseph Agassi: A Philosopher's Apprentice: In Karl Popper's Workshop . Editions Rodopi, 1993, ISBN 90-5183-563-9 . Autobiographical report by Agassi about the impression Popper left on him.
  • William W. Bartley: Karl Popper: A life . unpublished

English language study guides

  • Roberta Corvi: An Introduction to the Thought of Karl Popper . from the Italian by Patrick Camiller, Routledge paperback, 1996, 209 pages. A very good analysis of Popper's work with many references to the relevant text passages.
  • Steve Fuller: Kuhn vs. Popper: the struggle for the soul of science . Icon, Cambridge 2003 (Reprints 2003, 2004, 2006). Very well readable study on the theoretical argument between Popper and Kuhn and at the same time an interesting assessment of the (mis) reception of Popper as traditional and Kuhn as progressive. In the author's view, it is rather the other way round.
  • J. Shearmur, G. Stokes (Eds.): The Cambridge Companion to Popper , Cambridge University Press (24 Jun. 2016), 404 S. Comprehensive and valuable study guide.

Web links

Commons : Karl Popper  - collection of pictures, videos and audio files
Overview of Popper's philosophy
Secondary literature on more specific issues
Institutes, material collections and others

Individual evidence

  1. ^ William W. Bartley : Rationality versus the Theory of Rationality , In Mario Bunge: The Critical Approach to Science and Philosophy (The Free Press of Glencoe, 1964), section IX.
  2. ^ Letter from Karl Popper to Hans WL Biester from 1990 letters . In: Berlinische monthly 7/2001 at the Luisenstädtischer Bildungsverein
  3. Philosophy Channel : Karl Popper - A Conversation (1974). July 3, 2013, accessed April 1, 2016 .
  4. Thomas Prlic: The carpenter as a philosopher Tischler Journal 12/12, p. 24, November 28, 2012, accessed October 23, 2019. - Popper trained as a carpenter in a company in Gumpendorferstraße, passed his journeyman's examination in the guild house, 31 Ziegelofengasse and received the grade "good". His journeyman's certificate and a replica of his journeyman's piece have been exhibited here since 2012; the original wall box is in Popper's house in London.
  5. Sir Karl Popper's Gesellenstück tischlereikonecny.at, 2012, accessed October 23, 2019.
  6. http://www.bundesheer.at/truppendienst/verbindungen/artikel.php?id=893
  7. ^ Davis : The Open Society . (PDF) University of Nebraska Omaha , archived from the original on September 10, 2014 ; accessed on April 22, 2019 (English, original website no longer available).
  8. Karl Popper: Some remarks about the Viennese school reform and its influence on me . In: Early Writings. Mohr Siebeck, Tübingen 2006, ISBN 978-3-16-147631-0
  9. Catalog slip at the University Library Vienna . See Thomas Sturm: Bühler and Popper: Kantian therapies for the crisis in psychology in: Studies in History and Philosophy of Biological and Biomedical Sciences , 43 (2012), pp. 462-472
  10. ^ William Warren Bartley : The Austrian school reform as the cradle of modern philosophy . in: Club Voltaire IV, ed. Gerhard Szczesny, Hamburg 1970, ISBN 3-499-65086-X , p. 360
  11. ^ Karl Popper: Some remarks about the Viennese school reform and its influence on me [1970], Troels E. Hansen: Afterword of the editor, Section VIII Appendix: Some remarks about the Viennese school reform and its influence on me . In: Früh Schriften , Mohr, Tübingen 2006, pp. 497, 543
  12. See, among others, Edmonds / Eidinow 2005
  13. Martin Morgenstern , Robert Zimmer (ed.): Hans Albert / Karl Popper, correspondence. Fischer Taschenbuch, Frankfurt am Main 2005, ISBN 978-3-596-16586-5 , p. 137.
  14. ^ Edward Zerin: Karl Popper On God: The Lost Interview. Skeptic 6 : 2 (1998)
  15. David Miller: Sir Karl Popper: A Personal Note . Popper Letters 6 : 2 (1994)
  16. ^ Date of burial according to information from the cemetery administration on April 24, 2013
  17. https://www.popperschule.at/philosophie.html
  18. ^ William Warren Bartley : Critical Study: The Philosophy of Karl Popper. Part I. Philosophia 6 : 3-4 (1976), pp. 463-494
  19. ^ William Warren Bartley : Critical Study. The Philosophy of Karl Popper. Part II. Philosophia 7 : 3-4 (1978), pp. 675-716.
  20. On the first day of the Vienna Popper Symposium on May 24, 1983, Popper said that both creativity and criticism were equally correct: “So my theory of science is incredibly simple. It is we who create the scientific theories, it is we who criticize the scientific theories. That's the whole theory of science. We make up the theories and we kill our theories. We create new problems and get into a situation in which we invent new theories if we can. In a nutshell, that is science and the history of science. ”(Karl R. Popper, Konrad Lorenz: The future is open , original edition. Piper 1985, p. 52, ISBN 3-492-00640-X .)
  21. ^ A b Karl Popper: Logic of Research . 9th edition. Mohr, Tübingen 1989, ISBN 3-16-345485-2 , pp. 59 .
  22. Starting points. My intellectual development, Hamburg 1979, 176 f.
  23. ^ Karl Popper: Logic of Research . 9th edition. Mohr, Tübingen 1989, ISBN 3-16-345485-2 , pp. 59 . , P. 15
  24. ^ Karl Popper: Logic of Research . 9th edition. Mohr, Tübingen 1989, ISBN 3-16-345485-2 , pp. 59 . , P. 13
  25. ^ Objective knowledge, pp. 37–44
  26. See In Search of a Better World , p. 103
  27. Quotation: "In the meantime I have found the terms 'open' and 'closed' society in Heinrich Heine." Source: The open society and their enemies , Vol. I, page 242 at the end of the note to the introduction in the Uni-Taschenbuch 1724, ISBN 3-8252-1724-8 . This note was added after 1943.
  28. a b c Lectures by Karl Popper - How I see philosophy. 1974, accessed on July 28, 2012 (Lecture by Karl Poppers from 1974, YouTube video (audio)).
  29. ^ Karl Popper: The open society and their enemies , 8th edition, Tübingen 2003, introduction, p. IX; The comment with the concentration camps refers to the following passage in Plato's Nomoi (Book X): If someone has been found guilty of godlessness [ie an offense against the laws of the ideal Platonic state], the court should give each [...] a special one Grant punishment, so that jail time affects them all, but since there are three prisons in the state, a general […], a second […] which is called the Besserungshaus, and a third finally inside the country in a desolate one and wild region, which should have some name which denotes a shameful punishment and thus inspires a holy shudder, […] but all those […] who [are] of the opinion that there are no gods […] all such people should if they have been referred to such a crime, they are sentenced by the court under the law to be incarcerated in chains in the interior prisons for life, and k a free citizen should ever be allowed to visit them, but the food intended for them by the law enforcers [should] be served them by slaves. But after their death they will be thrown out of the country unburied. (Translation after Franz Susemihl , 1862)
  30. The open society and its enemies , Vol. I, 67f.
  31. ^ The open society and its enemies , Volume I: The Magic of Plato , 8th edition, Tübingen 2003, pp. 161f.
  32. The open society and its enemies , Vol. II., 73f.
  33. See, for example, In Search of a Better World, Munich 1984, 25f.
  34. ^ Karl R. Popper: What is dialectic? In: Ernst Topitsch (Ed.): Logic of the Social Sciences Vol. 5 (1968), pp. 262–290 ( digitized version (PDF; 325 kB)).
  35. Karl R. Popper: Against the big words. In: Die Zeit , September 24, 1971.
  36. In search of a better world. In: Piper , Munich 1984, 99, 100, 103.
  37. ^ Karl Popper (2004) All people are philosophers , Piper series, Munich / Zurich, ISBN 978-3-492-24189-2 ; ISBN 3-492-24189-1
  38. ^ Letters with Albert Einstein 1935. In: K. Popper, Logic of Research. 9th edition. Mohr, Tübingen 1989, p. 413, Appendix XII.
  39. ^ The structure of scientific revolutions, Frankfurt / M. 1967 (1962)
  40. Normal science and its dangers, in: I. Lakatos / A. Musgrave (ed.), Critique and Knowledge Progress, London 1970, 51–57
  41. ^ Problems and results of the philosophy of science and analytical philosophy, Vol. II (Theory and Experience), Part E, Berlin / Heidelberg 1973
  42. ^ Proofs and Refutations, Cambridge 1976
  43. Against the method constraint. Sketch of an anarchist epistemology, Frankfurt / M. 1976
  44. a b Gebhard Kirchgässner (2002): All life is problem solving: On the 100th birthday of Karl Raimund Popper (Download, PDF, 434 kB) , in: Wirtschaftsdienst, 82nd year (2002), no. 9, p. 567 -572.
  45. ^ Ronald Bartlett Levinson: In Defense of Plato , Russell & Russell, 1970
  46. Walter Kaufmann: Hegel: Legend and Reality (PDF; 2.2 MB) In: Journal for Philosophical Research Volume X, 1956, 191–226.
  47. ^ Maurice Cornforth: The Open Philosophy and the Open Society: A Reply to Dr. Karl Popper's Refutations of Marxism , New York: International Publishers, 1968.
  48. ^ Charles Taylor: Overcoming Epistemology. Philosophical Arguments (Harvard University Press, 1995).
  49. WW Bartley, III: Biology & evolutionary epistemology. Philosophia 6 : 3-4 (September – December 1976), pp. 463-494
  50. WW Bartley: A Popperian Harvest. In Paul Levison: In Pursuit of Truth (1982), Section III, pp. 268ff
  51. Rafe Champion: Free Speech or Pulp Fictions? . John Dewey Discussion List (28 Jan 2003)
  52. Rafe Champion: Agreeing to Disagree: Bartley's Critique of Reason . Melbourne Age Monthly Review (October 1985)
  53. David Miller: Some hard questions for critical rationalism
  54. ↑ Entangled in controversy. From cultural pessimism to critical rationalism, Berlin / Vienna 2007, z. B. 173
  55. http://public.econ.duke.edu/~bjc18/docs/Popper%20and%20Hayek%20-%20Who%20Influenced%20Whom.pdf
  56. Karl Raimund Popper, ed. Troels Eggers Hansen: The two basic problems of epistemology , Tübingen 1979, p. 182
  57. Wolfgang Wurm: Obituary for Hofrat Dr. Franz Austeda. In: ahs current. Episode 167, May 2009, p. 12.
  58. David Miller: Sir Karl Raimund Popper In: Biographical Memoirs of Fellows of the Royal Society , 1997, Vol. 43, p. 403.
  59. ^ Deceased Fellows. British Academy, accessed July 20, 2020 .
  60. David Miller: Sir Karl Raimund Popper In: Biographical Memoirs of Fellows of the Royal Society , 1997, Vol. 43, p. 404.
  61. therein essay Utopia and Violence. 1947. Excerpt from it in Martin Morgenstern , Robert Zimmer Ed .: State foundations and historical meanings . Series Meeting Point Philosophy, 4: Political Philosophy . Bayerischer Schulbuch Verlag BSV, Munich 2001 ISBN 3-7627-0325-6 ; Patmos, Düsseldorf 2001, ISBN 3-491-75641-3 , pp. 136-138 udT: Critique of utopian thinking