Critical Rationalism

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The critical rationalism is one of Karl Popper reasoned philosophical mindset. Popper describes it as an attitude to life "that admits that I can be wrong, that you can be right and that together we may come to the truth on the track". It is characterized by a cautiously optimistic perspective on life and things, which is expressed in the book titles All Life Is Problem Solving and In Search of a Better World .

Critical rationalism deals with the question of how scientific or social (but in principle also everyday) problems can be examined and resolved in an undogmatic, planned ('methodical') and reasonable ('rational') manner. In doing so, he is looking for a way out of the choice between belief in science ( scientism ) and the view that scientific knowledge must be based on positive findings ( positivism ), on the one hand and the point of view that truth depends on the perspective ( relativism ) and that on the other knowledge of arbitrariness is revealed if evidence is impossible (Truth skepticism ).

Critical rationalism adopts the common sense self-evident belief that the world really exists and that it is independent of human knowledge . This means, for example, that it does not cease to exist when you close your eyes. But the human being is limited in his ability to cognize this world through his perception, so that he cannot obtain any final certainty as to whether his experiences and opinions agree with actual reality ( critical realism ). He must therefore assume that each of his problem-solving attempts can be wrong ( fallibilism ). The awareness of fallibility leads on the one hand to the demand for constant critical examination of convictions and assumptions, on the other hand to a methodical and rational approach to solving problems ( methodological rationalism ).

Critical rationalism regards any scientific theory as fundamentally unprovable. Instead, we should try to find out if and where our theories could be flawed and how to eliminate errors that are discovered. In order to be considered scientific, a scientific theory should in principle fail due to reality. This is the principle of falsifiability (which must be carefully distinguished from actual falsification , comparable to the difference between destructibility and destruction). A strong argument (in the form of a scientific historical example) for any failures (instead of documents) to look for a theory that detachment is gravitational theory of Isaac Newton by the theory of relativity of Albert Einstein : After Newton had set up his theory, it was 200 years long time and again confirmed without exception by observation. If a scientific theory could ever have been considered proven, it would most likely have been Newtonian. Still, Einstein doubted its correctness and contrasted it with his own theory. Compared to this new theory, Newton's theory approximately agreed on a limited area of ​​reality, but outside this area it was flawed (as falsified by observations) and therefore in need of improvement. At this point in time at the latest, it could no longer have been used as an example of a (supposedly) safe theory, but rather that safe knowledge is only an illusion. Instead, Newton's theory was a good example of the fundamental fallibility of our striving for knowledge. Instead of claiming for his part that he was able to provide methods to prove his own theory, Einstein proposed sophisticated experiments to test them and stated the circumstances under which he would be forced to reject them again. The critical rationalism of Karl Popper took a. these events serve as a model for a successful scientific and cognitive process.

The approach recommended by Einstein suggests how scientific problems can be solved through trial and error : if his theory had failed the suggested tests, one could have tried another. Before Einstein's revolution in physics, it was widely believed that evidence of scientific theories was possible through the method of induction . This is the generalization of a state of affairs based on individual observations. However, the epistemological position of Critical Rationalism does not reject the provability of a theory by induction, but instead demands its falsifiability , i.e. the fundamental possibility of finding counter-examples through experimentation and observation and thus refuting the theory.

Critical Rationalism's position on politics is very similar to its position on science. It is not important here how to find the best ruler in advance or what one should do to ensure ideal conditions. Instead, it is much more important how bad rulers can be deposed bloodlessly and grievances remedied.

Likewise, in the field of ethics and society, he eschews justification for norms and instead focuses on the question of how bad rules can be recognized and improved. For Critical Rationalism, ethics is problem-solving in the social field. Here, too, he calls for a critical-rational approach and the renunciation of any dogma . As in science, new, better solutions are found using the principle of trial and error. In order to avoid serious negative effects of experiments in this area, critical rationalism advocates a policy of small steps (“piecemeal engineering”).

In each of these areas, critical rationalism applies the principle of criticism, which is based on observation, checking for self-contradictions, contradictions to empirical-scientific theories and on the success control with regard to the problem to be solved. He gives creativity, imagination and astonishment at the world a place that clearly distances itself from the traditional image of the strict sterility of science. It is not understood as a steady accumulation of infallible truths, but on the other hand also not as the building of castles in the air. From the point of view of Critical Rationalism, it is rather a great adventure and an exciting journey of discovery.

With its basic view that all human beings are fallible, Critical Rationalism turns against all positions that assume the possibility of an ultimate justification (for example with regard to moral norms). He advocates an open, pluralistic society that is tolerant of all peaceful people, that resolves conflicts through rational discussion and the sincere search for truth; in which people are free to give their life an individual meaning and to be able to find their way in an open future. However, this is not understood as a social utopia, but as a defense of the actually existing western democracies against cynical contemporary pessimism as well as against real existing totalitarian states. In this sense he fights against all forms of tutelage by authorities , intolerance and ideology , totalitarianism and irrationalism .


Critical Rationalism was founded by Karl Popper as part of his examination of the theory of science and social philosophy . (He introduced this term in 1944 in his work The Open Society and Its Enemies , but developed the basic content in his earlier works.) He developed his most comprehensive presentation in Objective Knowledge .

There are also divergent modifications, some of which are fundamentally different. William W. Bartley dealt in Flucht into Engagement with the question of whether Critical Rationalism meets its own requirements when it is applied to itself and can thus be accepted without loss of integrity . Hans Albert developed it further for the social sciences and humanities and systematically elaborated it in his treatise on critical reason . Reinhold Zippelius adopted and developed it as a fundamental method of legal thought . A contemporary representative who connects the approaches of Popper and Bartley, develops them further and deals with criticism is David Miller . These positions are closest to Popper's.

Joseph Agassi dealt with basic questions about the conception of rationality, but solved them in a different way than Bartley. Imre Lakatos designed a heavily modified, conservative form of critical rationalism that is more geared towards protecting the hard core of a theory. Variants with elements of the classical strategy of justification were developed by John WN Watkins and Alan Musgrave . Adolf Grünbaum and Wesley C. Salmon advocated modifications with inductivist elements. Gerhard Vollmer tried to combine critical rationalism with naturalism.

The ideological spectrum among the supporters of critical rationalism ranges from rigorous supporters of atheism , religious criticism and the skeptical movement such as Michael Schmidt-Salomon and Bernulf Kanitscheider to the Opus Dei priest Mariano Artigas (1938–2006). Popper represented a respectful agnosticism towards believers; Bartley followed the teachings of Werner Erhard , the founder of the controversial EST (Erhard Seminar Training).

In 2020 the Hans Albert Institute was founded, which sees itself as a “think tank for the promotion of critical-rational thinking in politics, business and society”. The board of directors and the scientific advisory board include leading representatives of critical rationalism in German-speaking countries.


Critical realism

The realism is the subjective idealism contradictory metaphysical theory that an independent human reality exists. While naive realism assumes that the world is the way people perceive it, critical realism takes the view that ideas of it are more or less strongly influenced by subjective elements that lie in perception and thinking. Because the senses and the processing processes in the brain are interposed between the assumed outside world and the imagination, one can also speak of indirect realism. This mediation process excludes “pure perception” because it can be a matter of deceptions.

Critical realism is not an ontological assumption that precedes science, but is a metaphysical consequence of empirical-scientific theories. (Popper argued against anti-realistic tendencies in quantum theory with a realistic interpretation that he himself established and further developed.) However, it is not only to be understood cosmologically (an external world exists), but also epistemologically: by establishing a mistake in the context of a falsification and corrects it, it approaches the knowledge of reality. He will never know whether or to what extent he has come closer to it, but replacing an error with a better explanation means a better knowledge of what the world really is like.

Independent of this, there is also a position in the universality dispute called realism. This position assumes that general terms have a real existence. Specifically, this is, for example, the assertion that there is real art, real people or the real state. Critical Rationalism strictly rejects this position, as it is related to the assertion that things have essential properties and concepts of an essence, a nature or a core that cannot be changed. Popper calls it essentialism to avoid misunderstandings . Essentialism manifests itself in “thinking in terms” and in questions that begin with “what is”, e.g. B. “What is the state?” Or “What is life?” According to Popper, they must be replaced by a discussion of problems, for example “How much should the state interfere in the private affairs of citizens?” Or “Should abortions be punished be? ”Popper himself first represented nominalism , for which terms are purely conventional means of abbreviation. In his later metaphysical work he professed a modified essentialism, which admits that in a development process from generation to generation some characteristics are always inherited and thus preserved, and that some characteristics are subject to a stronger selection than others. However, he rejected the view that there is a core among these properties that is excluded from the change in a special, principled way.


The goal of making correct statements with theories leads to the question of whether reality is recognizable. Critical rationalism assumes that, due to the logical properties of all truth theories, it is not possible to give a reliable justification for truth. Because every attempt to prove the truth of a statement leads either to an infinite regress, a logical circle or to a termination of the evidence process, often with reference to the evidence of the statement (see Münchhausen Trilemma ). Any such termination means that no strict reasoning of the truth has taken place.

The solution of critical rationalism assumes that knowledge is always only a hypothetical knowledge, a presumptive (conjectural) knowledge, which is based on the classical determination of truth as the correspondence of a statement with a fact. According to Alfred Tarski , truth can not be defined by a criterion; nevertheless, the semantic use of the term 'truth' in normal language, i.e. the truth as correspondence with the facts, is unproblematic in any concrete application.

Despite the conclusion that one can never know whether one has found absolute truth, critical rationalism sticks to its existence and rejects relativism, i.e. the dependence of truth on the point of view. So you can have found the truth and pronounce a true sentence, but you cannot prove that it is true. This is as true of everyday claims as it is of theories of science.

Critical rationalism, however, does not yet see the lack of certainty of an assertion - like, for example, the skepticism of truth - as a necessary reason to doubt its truth. He argues against the skepticism of truth with the objection that it makes rational sense to accept a theory as true on a trial basis if it is openly defended and no arguments have (so far) been found against its tenability. Because without theories, even the most common problems cannot be solved. In addition, falsehood is not fatal: the wrong theory can still have many true consequences or provide explanations that are helpful in practice.

This view also leads to a pluralism of theories , since there are usually several alternatives that are acceptable according to the state of the discussion and can be tried out. It is rational to critically question existing theories to a sufficient extent and to always keep an eye on the necessity of checking experience. Instead of thinking about evidence, there is the idea of ​​critical examination. - "Look before you leap!"

Building on this, elements of empiricism, naturalism and constructivism can also be integrated into critical rationalism. So it is reasonable to take perceptual judgments as hypotheses that are usually true, as long as one takes into account that there are circumstances of the perceptual illusions. Here Critical Rationalism does not differ from common sense . So perception is a very unproblematic element, and even if it leads to inconclusive results, clarification is usually straightforward. Even if perceptual judgments become problematic in retrospect, they can always be checked and revised through further perception.

The unproblematic perception base is central to critical rationalism, because without it, assumptions about reality would not be subject to any control. The fact that it is unproblematic, however, cannot be inevitable: It can be explained very well naturalistically with the evolutionary adaptation of the human sensory organs to their environment (see evolutionary epistemology ). It is also possible for Critical Rationalism to accept the constructivist thesis that man does not read the laws of nature in the 'book of nature', but that he invents them and, as Kant said, prescribes them for nature. Laws of nature are hypotheses about the world that always require critical examination.

Negativism and skepticism of knowledge

In addition to fallibilism, critical rationalism also includes knowledge skepticism. Fallibilism only says that the truth of a statement cannot be substantiated. Knowledge skepticism goes even further and maintains that even the assumption that a statement is true cannot be justified. From this, however, one must not infer a skepticism of truth: It does not follow that everything that is held to be true must be doubted in the truth, or that it is even forbidden to hold something true or to judge something as true.

Popper agreed with Bartley and Miller that there can never be good, positive reasons for believing anything: good reasons don't exist; if they existed they would be useless; and they are not needed for rationality either. (While Popper interpreted the degree of probation - the degree to which an assertion has withstood criticism - as a measure of the rationality of tentatively assuming a guess, according to Bartley, these passages must be ignored if the coherence of the overall context is to be preserved must be viewed as epistemologically completely irrelevant.) Rational arguments, on the other hand, are indispensable, but are always negative and critical (' negativism '). Whether one accepts an assumption or an argument is always a free decision of will and conscience and cannot be forced through argumentation. Rationality lies in rejecting a successfully criticized assumption.

However, a lack of good reasons does not make an assumption purely arbitrary. Because a reciprocal control of assumptions among each other is possible (' checks and balances '). Acceptance always includes rejecting alternatives. However, this negative rejection does not become a positive reason for acceptance: It is just as rational to think up a new alternative. It also makes sense not to accept any alternative at all if they are all uninteresting for the problem to be solved. Acceptance is a critical preference, a fallible, but also criticizable and revisable judgment with which one determines what one tentatively considers to be true. Every judgment is therefore a prejudice.

Critical rationalism thus rejects the classic idea that there are procedures with which knowledge is substantiated (certain, acceptable, acceptable, firm, reliable, trustworthy, credible, probable or reliable, justified, proven, recognized, verified, guaranteed, vouched for, confirmed, substantiated, supported, legitimized, evidence-based, established, secured, defended, validated, authorized, vindicated, strengthened or kept alive) and that reason is characterized by the use of such procedures. Logic is therefore an “organon of criticism”, not an instrument for positive justification or justification.


Hans Albert has put together a catalog of principles of logic that helps with simple basic statements to check and assess the plausibility of statements and theories. According to Albert, these principles exist independently of the philosophy of critical rationalism; their use, however, corresponds to the spirit of his worldview and they convey a piece of wisdom that can be used even without a deeper knowledge of logic.

Only truth can follow from truth.

The basic principle of deduction , that with a true major premise and a true premise, the truth is translated into the conclusion . The reverse is important for science and everyday thinking: if something wrong follows, at least one of the premises (or the major premise) must be wrong.

Truth can follow from falsehood.

Logically, wrong assumptions can lead to a conclusion that makes a true statement. So even if a theory's predictions are correct, the theory itself can be wrong. This fact complements fallibilism on a logical level. It also forbids inferring the correctness of the theory itself from correct predictions of a theory. Conversely, he explains why a wrong theory does not have to be a bad theory and why fallibilism is therefore not reduced to absurdity due to the inevitable risk of theories being falsehood that it predicts.

Infinitely many propositions follow from every theory.

This sentence also harmonizes with fallibilism. Since man's knowledge is finite, he cannot know whether a theory leads to a statement that turns out to be false and thus falsifies the theory.

There are an infinite number of theories that can explain observations .

Even if a theory explains a fact well, it should not be assumed that the theory provides the best explanation. There can be a better one.

Any assertions follow from contradictions.

Every indication of a contradiction in a theory is an invitation to find a new, consistent theory. Dialectics understood in this sense is a principle for clearing up contradictions.

Only statements that are meaningful contain information.

The higher the content of a statement, that is, the more specifically it says what it includes and what it excludes, the better it can be checked.

There are no wage-widening conclusions.

You cannot acquire additional knowledge with the help of logic. Therefore, inductive inferences that conclude from little knowledge to much knowledge cannot be logical inferences. At most, they have a heuristic value and are not mandatory.

Philosophy of science

Are all swans white? The classical view of the philosophy of science was that it is the task of science to “prove” such hypotheses or to derive them from observational data. However, this seems difficult to do, since a general rule would have to be deduced from individual cases, which is not logically permissible. But if we find a black swan, we can logically conclude that the statement that all swans are white is wrong. Falsificationism thus seeks to question, to falsify , hypotheses instead of attempting to prove them.

Popper's examination of the philosophy of science of logical empiricism had a major influence on critical rationalism . Based on Mach's positivism and the analytical (language) philosophy of the mathematicians Frege and Russell , the members of the Vienna Circle tried to develop a philosophy based on language analysis and logic within the framework of a physicalistic worldview . The aim was to build a unified science . In this philosophy of science should function as the theory of the language of science. Theorems of philosophy that are not analytical (logic and mathematics) or empirical ('positive' sciences) must, according to logical empiricism, be viewed as pseudo-problems and are therefore not scientific. It must be possible to reduce empirical sentences to protocol sentences . These are basic sentences of experience and observation in the formal structure of the scientific language to be developed. Only statements that can be verified or confirmed in this context meet the necessary and sufficient conditions for meaningful factual statements.

Popper took a different path. He took the view that one of the main tasks of philosophy was to critically question the belief in the authority of observation that is characteristic of positivism. The basic idea that even the most certain theory could be wrong led him to oppose induction and verifiability on the one hand with the principle of falsification (search for errors, not just for new verifications) and on the other hand the criterion of falsifiability (only falsifiable theories are empirical ).

Induction problem

Inductive imagination: Science starts with observation, then generalizes and makes predictions based on that.

Inductivism is based on the assumption that by a sufficient number of observations by way of the inference of induction , that is, according to the scheme

This swan is white
Hence all swans are white


All known swans are white
Hence all swans are white

or in a specific application in physics

Objects fall down
further observations ...
Therefore the law of gravitation generally applies

general statements can be made about a subject area that have a legal character. The inductive inference is logically considered the conclusion from a case and a result to a rule. The conclusion is synthetic (the transition from assumption to conclusion increases the content of the statement) and is therefore not logically mandatory. The advocates of logical empiricism were of the opinion that such sentences are still useful if the theory (as a nomological hypothesis) can be confirmed by protocol sentences . The protocol records were required to meet the strict requirements of a scientific language. The confirmation of a theory by protocol sentences was then considered to be a verification of the theory.

Already Galileo had rejected the principle of induction. In a detailed review, Hume showed that a logical proof of induction is not possible. Hume had accordingly argued that the principle of causality rests on human habit which is useful to follow. Even Albert Einstein rejected the induction. His point of view was the motivation for Popper to deal intensively with the topic and to show that general empirical statements or theories cannot be verified, but only falsified. The concept of protocol sentences has the problem that they already presuppose theories (they are 'theory-laden'), so that the justification with the help of protocol sentences leads into a circle. The problems associated with induction are widely accepted in the philosophy of science. According to Wolfgang Stegmüller: “Either one conclusion is correct; then it is truth-preserving, but not widening the salary. Or else it is wage-widening; then we have no guarantee that the conclusion is true, even if all the premises are correct. "

However, Popper viewed induction not only as unfounded, but as nonexistent: From his point of view, there is in reality no generalization from individual cases to general propositions at all - it is an illusion. The generalization, i.e. the theory, must (possibly unconsciously) already exist before an observation is even possible. Induction is therefore not rejected in Critical Rationalism because it is unfounded, but because the assumption that there is such a thing as an induction or generalization conclusion can be deductively refuted. An induction principle is therefore not present even with the formation of hypotheses: In the transition from “This swan is white” to “Therefore all swans are white”, theories about white color and about swans are in the background. Either these together already contained the property - then it is simply two deductive consequences written one after the other - or, if they did not contain this, then it was added during the transition to the theories and the meanings of "white" and "swan" have changed thus changed unsystematically. The illusion of a systematic induction rule only arises from the use of the same words.

Even if induction is not a strict logical conclusion, it could at least allow strong conclusions to be drawn about probabilities. Logical empiricism, especially Rudolf Carnap , advocated such an interpretation of induction. From this point of view, that theory is the most rational choice that has the highest inductive probability given the basis of observation (evidence material). In the logic of research, Popper took the position that there is no induction of probability and that all theories can basically only have logical probability . In several successive appendices to the book, he tried at length to refute the thesis of the possibility of a probabilistic induction principle even under the unjustified assumption that theories have greater probabilities . In 1983, together with David Miller, he published one last “very simple proof” in which he tried to show that deductive relationships logically undermine any probability-based induction. This evidence has sparked controversy.

Falsification is Popper's attempt to get by without the principle of induction or regularity, while at the same time avoiding falling back on such a principle in a covert way. The basic idea is that regularities must exist in nature for the falsification to deliver results, but that one can dispense with the assumption that they exist: In the event that there are no regularities in nature, it delivers Falsification no result, since then every hypothesis is falsified that predicts regularities. Induction, on the other hand, produces false results in such a situation. Instead of a principle of regularity, Popper introduced the methodological rule that laws of nature should always be formulated independently of time and place. Falsification also eliminates the circular problem that verification has with theory-laden observation. This is because the theory is not used to form observational sentences that it should in turn confirm, but to derive a contradiction from the assumption that it is true. This is possible due to a fundamental asymmetry in deductive logic, which Popper calls the "asymmetry of verification and falsification".

Similar to the induction principle, Popper also eliminates other metaphysical requirements that are indispensable for empirical science from a positivist point of view (e.g. realism, causal principle) by replacing them with appropriate methodological rules. Thus, empirical science turns from a system of empirically unassailable metaphysical presuppositions which, together with observations, are intended to justify empirical-scientific theories, to a method of testing and correcting these theories. The falsification method itself does not have to be presupposed either, but simply applied - in this sense it is “free of any preconditions”. The scientific methodology shifts the problem: The goal of excluding errors in hypotheses in advance is abandoned as impossible and replaced by the new goal of designing the hypotheses in such a way that they can be recognized as incorrect and corrected as easily as possible afterwards can when they should be wrong.

Demarcation problem

Because empirical theories cannot finally be decided, Popper developed the criterion of falsifiability as an alternative solution to the delimitation problem for empirical sciences. Popper saw this delimitation problem, i.e. the question of how empirical-scientific and metaphysical sentences can be distinguished from one another, as the more important problem compared to the induction problem, i.e. the question of how theories can be justified by special sentences.

"An empirical-scientific system must be able to fail because of experience."

His aim is to provide a rational, systematic and objective, i.e. intersubjectively verifiable, instrument with the delimitation criterion of falsifiability.

Popper made a fundamental distinction between logical falsifiability and practical falsifiability. A theory is empirical if there is at least one observation sentence that logically contradicts it. It cannot be ruled out that in practice, due to a lack of suitable experiments (for example in astronomy or atomic physics), an actual observation cannot be carried out at all. Statements that are not falsifiable (refutable), i.e. not empirical-scientific, are metaphysical .

Definitions are not falsifiable. Therefore, statements that implicitly contain the definition of what is said cannot be falsified. If the phrase “all swans are white” implies that it is an essential characteristic of swans to be white, it cannot be refuted by the existence of a black bird that otherwise has the characteristics of a swan. Because according to the definition, it would not be a swan due to its color. If, on the other hand, the color is not part of the definition of a swan, the sentence “All swans are white” can be checked by contrasting it with an observation sentence: “There is a black swan in the Duisburg Zoo”, regardless of whether there is really one black swan exists.

Likewise, the axioms of mathematics are not falsifiable as stipulations. They can then be checked to see whether they are consistent, independent of one another, complete and necessary for the derivation (deduction) of the statements of a system of theories. The change in the axiom of parallels in the 19th century led to the development of other geometries in addition to the Euclidean one. But this did not falsify Euclidean geometry. However, without these non-linear geometries, the development of the theory of relativity would not have been possible.

"A theory is falsifiable if the class of its falsification possibilities is not empty."

Contradicting statements are in principle falsifiable, but this falsifiability is of no value. By means of the principle of excluded contradiction, one can deduce any consequence from them. In particular, it follows from this for every basic sentence its opposite. However, this means that every basic sentence falsifies a contradicting statement.

To distinguish scientific theories from pseudoscientific (or general rationality from pseudorationality), critical rationalism does not depend on falsifiability, but rather the question of whether it contains a ' double entrenched dogmatism '. While any theory can be immunized against criticism if it is unscientific, such dogmatisms compel immunization even if they are placed in a scientific and critical-rational context. However, they do not in principle withdraw a thesis from critical analysis, but only have to be removed before discussion.

The common mistake of seeing a lack of falsifiability as something bad or even as a mark of nonsense, even Albert admitted, who initially linked Popper's position with the point of view that metaphysics was pointless. Popper had explicitly not seen it that way, but emphasized several times that in the first edition of the logic of research he had wrongly equated the limit of science with the limit of debatable, and that he had changed his mind on this point.

Critical rationalism itself cannot be falsified. However, it can be criticized and rationally discussed (see Pancritical Rationalism ).


One goal of Logical Empiricism was to expose metaphysics as meaningless and only allow those theories in science that are completely verifiable, i.e. can be reduced completely to observational sentences. However, every theory always has a metaphysical content in the form of elements and conclusions that go beyond mere observation. A simple example is the empirical theory that people live to be no more than 150 years old, and the resulting metaphysical statement that all people are mortal.

There is an essential difference between the requirement of verifiability and the criterion of falsifiability in attitudes towards such facts: Logical empiricism regards metaphysical elements as problematic and tries to correct theories about them as far as possible. Critical rationalism, on the other hand, harmonizes with them because of its realistic basic attitude and considers them permissible and desirable as long as the theory as a whole remains falsifiable. Because they say something about the nature of reality.

Popper was also of the opinion that purely metaphysical sentences also make sense. They are myths and dreams which, through their creative power, help science to discover new problems, to construct new, falsifiable theories and thus to give itself purposes and goals. He called them metaphysical research programs and listed the ten most important in his view:

  1. The idea of ​​the universe as a uniform, unchangeable sphere ( Parmenides )
  2. The atomic concept
  3. The geometry program ( Plato and others)
  4. The concepts of essential properties and powers ( Aristotle )
  5. Physics at the time of the Renaissance ( Kepler , Galilei and others)
  6. The clockwork theory of the universe ( Descartes and others)
  7. The theory that the universe is made up of forces ( Newton , Leibniz , Kant and Boscovich )
  8. The field theory ( Faraday and Maxwell )
  9. The idea of ​​a unified field ( Einstein and others)
  10. The indeterministic particle theory (as in Born's interpretation of quantum theory)

For example, the Greek philosophers' idea of ​​the atom was a purely metaphysical idea for 2300 years before theories based on the idea emerged in the 19th century, which could be tested experimentally and proved themselves - at least for a certain time. If there are metaphysical sentences such as All people are mortal or There are positrons isolated for themselves, they are pre-scientific . An empirical theory only arises when a property is predicted that can be checked using an observation set (basic set). The statement that everyone dies 150 years after their birth at the latest can be tested . Should there ever be someone who gets older, this theory is falsified. Metaphysical statements are basically allowed in empirical science as long as they appear piggyback as a consequence of falsifiable theories.

Metaphysics can still be criticized despite its non-falsifiability, since falsification is only one form of logically valid, rational criticism. Popper added his own eleventh metaphysical research program to his list, which linked and expanded these ten: the conception of the universe as a unified propensity field .

Cognition progress

Development scheme of the progress of knowledge according to Popper

The search for falsifications, for the conceivable cases of application where theories fail, i.e. ultimately the search for errors, was viewed by Popper as crucial for the progress of knowledge. Only the correction of these errors through better theories leads to progress.

With the method of falsification, the context of discovery and explanation are separated. Falsification is a method of assessing existing theories. According to Critical Rationalism, there is no methodologically rational procedure for discovering theories. It is a creative process that is essentially influenced by speculative imagination, intuition, chance and flashes of inspiration. So theories are always fictitious. Einstein had also represented this view. Here, critical rationalism particularly opposes the pessimistic attitude “nothing comes from nothing”: theories are always based on existing knowledge, including innate knowledge (such as the tendency to learn a language), but their innovations literally arise from this Nothing. With them, something new enters the universe that was not there before.

But Popper rejected the existence of a scientific method in the usual sense. For him there is really only one general method, the method of trial and error, which is also used in philosophy and in every other field as a method of criticism and in science as falsification. But even when it comes to human knowledge, Popper did not draw any limits. He regarded it as a basic principle of all action, which can be found in all areas of nature up to and including the amoeba, that after every failed attempt in world orientation a new alternative path is sought and started. Scientists act accordingly. Every falsification leads to modifications of existing theories or the construction of new theories until a theory is sufficiently proven . In the search for solutions to new problems, tried and tested theories are therefore repeatedly put to the test, prove themselves again or are falsified and replaced by modified or new theories. The bolder the new theories, the greater the progress. In addition, the boldness of the theory increases the possibility of falsification, and thus the range of possible experiments for verification, which can be used for further research.

As part of this process, an ever higher level of knowledge is reached. A theory represents an advance in knowledge compared to another theory if it is closer to the truth . Proximity to the truth cannot be measured. However, the closeness to truth of two theories can be compared as a model. Compared to another theory, a theory is closer to the truth if it is “more substantial” and if it offers more or better explanations for facts than the weaker theory.

“Substantial” does not mean the logical truth content of a theory (the set of all true statements that follow from it), but the “informative content”. That is the set of all statements that the theory excludes. The statement "Tomorrow there will be a south wind" is more meaningful than the statement "Tomorrow the winds will blow from different directions" because the former excludes north, west and east wind. Science is looking for such 'substantial' statements. If it were to look for a high level of logical truth, it would come to meaningless, almost tautological statements. Even two statements that are both true can therefore have different closeness to the truth.

If one observes how the sciences advances from more specific theories to more and more general ones when this falsification method is used, the impression can arise that it advances inductively, which is why Popper also speaks of an unproblematic 'quasi-induction'. Popper is therefore of the opinion that there is no one true starting point, the first philosophy or the Archimedean point from which all knowledge can then be systematically derived, but that people always start from very many, often wrong starting points, through them Constantly correcting criticism and finding ever more general principles with which these starting points can be unified.

Popper always emphasized that his research logic is not itself an empirical theory. It is a methodology that assumes that it is a matter of determining what is recognized as science. In particular, Popper turned against the ' naturalistic ' view of methodology, for which a method is scientific when it is actually used by science. The characterization of the scientific method by Critical Rationalism, as a normative proposal, does not claim to be consistent with the historical course of the history of science, although many events can be found that can in principle be interpreted as an application of this method. Because of its normative character, the falsification itself cannot be falsified. Because a method only says how to do something, not that something will be. Conversely, however, as a definition it is not “just arbitrary 'because it is conventional, that is, created by man”. It can be compared with other methods and promoted with arguments: “by analyzing its logical consequences, by pointing out its fertility, their enlightening power towards the epistemological problems. "


In Critical Rationalism, understanding is the counterpart to progress in knowledge. Progress in knowledge provides theories that explain facts. Understanding consists of the reconstruction of the historical problem situation in which the theory to be understood was set up. The aim of understanding is therefore a new theory that describes a problem and thus explains the attempt at a solution. Finding such an explanation is itself an attempt to solve another problem which, in turn, is open to understanding. This is the situation logic method .

Since this method relies on the critical method and because understanding is always also an explanation, there is no traditional opposition between the two in critical rationalism. Popper turns against the hermeneutic method of psychologization, which lacks objectivity because it tries to reduce everything to personal motives, and against the historicist method, which tries to understand everything as a historical necessity and thus has dogmatic traits. In critical rationalism history is problem history .

Objective knowledge

Progress in knowledge and understanding together result in an epistemology that recognizes that a totality perspective is not possible. Accordingly, the design and testing of any scientific theory is guided by interests, since it always takes place in the context of an attempt to solve certain problems. Every observation is loaded with theory. Natural sciences are just as dependent on the researcher's interests as historiography is not independent of the historian's perspective. There is always a selection of the facts and aspects in which the researcher is interested. The methods and instruments are designed in such a way that the researcher can realize his interests. He can easily overlook what is not in his focus. Popper spoke here of a " headlight theory ". What is not illuminated is not recognized.

Still, Popper was of the opinion that there is objective knowledge. By this he means that research results are intersubjectively verifiable and reproducible. Objective knowledge also has to do with subject-independent knowledge in a completely different sense: books, an architect's plan or other documentation preserve and transport knowledge without people having to communicate directly with this knowledge. This knowledge can affect people at any time and make a difference; and at any time people can influence this knowledge and use it e.g. B. improve. Popper classifies this knowledge as transcendent. It exceeds its material representation, since it has objective logical consequences that a person can never be aware of at the same time. They can be discovered little by little and very unexpected. He related Bertrand Russell's dictum “We never know what we are talking about” therefore not only to mathematics, but to all knowledge in general. For Popper, the material world, the world of objective knowledge and the intervening world of human consciousness are all real ( three-worlds doctrine ).

Society and Ethics


After critical rationalism rejects a final justification in epistemology, it also defends itself against all conceptions of accepting absolute values ​​or a supreme good as an Archimedean point . In terms of the delimitation criterion, ethics is not a science, since values ​​cannot be subjected to empirical verification through observation and experiment:

"Ethics is not a science."

Nevertheless, Popper and Albert took ethical positions and commented on ethical questions. This apparent contradiction is resolved because Critical Rationalism as philosophy - this is programmatic in the name - is a (logically unjustifiable) decision for rationality. It is a consciously chosen path between dogmatism, which is ruled out as logically untenable, and relativism, which makes irrationalism and laissez-faire possible. According to Popper, irrationality can be overcome through rationality. Rationality includes in particular:

  • Critical attitude with emphasis on argument and experience
  • Acceptance that everyone can make mistakes (fallibilism)
  • Readiness for critical troubleshooting (falsifiability)
  • Idea of ​​impartiality
  • Conclusion from one's own reason to the reason of the other
  • Rejection of claims to authority
  • Willingness to learn from mistakes (progress in knowledge)
  • Willingness to hear and examine others' arguments
  • Recognition of the principle of tolerance

The decision to use rationality (reason) is a basic ethical decision that Popper considers to be the only alternative that does not lead to violence in any form when resolving conflicts.

A basic distinction must be made between facts and standards. The term law is associated with both. In connection with regularities in nature, he refers to the laws of nature. Standards are normative laws made by people through conventions that regulate relationships between people. Laws of nature cannot be broken, but normative laws can.

"From the establishment of a fact, a sentence can never be derived that expresses a norm, a decision or a proposal for a certain procedure."

This logical statement is a formulation of the principle about the naturalistic fallacy .

"All discussions about the definition of the good or the possibility of defining it are completely useless."

The demand for freedom arises from the dualism of facts and norms as well as the basic decision for rationality. Freedom is freedom of thought and freedom to search for the truth. Freedom and responsibility are the basis for preserving human dignity.

“Only freedom makes human responsibility possible. But freedom is lost without responsibility; especially without intellectual responsibility. "

The basic demand for freedom and responsibility leads to plurality. That is why critical rationalism has often been accused of advocating a liberalist position. But whether a policy is conservative, liberal or socialist is a question of discourse. Philosophy can only accompany this discourse by examining the logic of the arguments, by examining whether ought also includes ability, and by urging adherence to rationality. Popper's philosophy also includes a criticism of laissez-faire liberalism. This is an ideology insofar as it understands the 'free market', which regulates everything for the good, as an empirical law of nature or as the result of science. But neither science nor nature can say what is good:

"Well, I still do believe that in a way one has to have a free market, but I also believe that to make a godhead out of the principle of the free market is nonsense."

Popper, who was a founding member of the Mont Pelerin Society, was occasionally classified as an early neoliberal due to his emphasis on individualism , but at the same time his complex humanitarian attitude was not considered typical even of early neoliberalism.

Open Society

As a consequence, the idea of criticism , the critical rationalism for an open society begins. Only in a society that is not bound by dogmas and rigid ways of life is there the possibility of constant reforms, i.e. improvements by eliminating errors and considering alternatives. In this way, the results of Popper's philosophy of science become politically effective.

Popper wrote his first socio-philosophical works ( The Misery of Historicism and The Open Society and Its Enemies ) while in exile in New Zealand. He saw it as a contribution to the fight against National Socialism . In order to clarify his position, he dealt critically, often also polemically shortened, with the state theory of Plato in the Politeia , with Hegel and Marx . The basic problem of such systems of ideas is that they are dogmatic and immunize themselves against criticism and refutation (see also justification strategy and conventionalistic twist ). Popper took the position that predictions of Marxism or communism about the future (e.g. in the form of the socialist revolution ) did not come true and the underlying theses were thus falsified. Instead of giving them up, from his point of view they have been enriched with “tightened dogmas” and have thus acquired a pseudo-scientific character.

As historicism called Popper considered that the course of history is determined independently of human agents of laws and that a great thinker can foresee this run. Plato's idea that a perfect state (ruled by philosophers) is achievable, the idea of ​​a chosen people, the meaning of history as the purpose of God, but also the historical necessity in Marxism ( teleology ) are such historicist theories. Teleology in history is just as impossible as the sure knowledge of an absolute truth. One can learn from history. But it is over today, and the future is open and dependent on people's choices. You are responsible for these decisions.

Linked to the teleological interpretation of history is the determination of an ideal towards which history strives. The ideologues who advocate this ideal often insist that everything possible be done to achieve the ideal. In Popper's eyes, Marxism , which has its philosophical starting point in Hegel, represents such a position . In addition to the accusation of having juggled with the language and spread verbal fog, Popper Hegel held up in particular a Prussian state philosophy in which the ruling king always has the right against the people on his side. Popper commented sympathetically on Marx's humanistic concerns (the abolition of class antagonisms, combating the misery of workers), but he massively criticized the political ideology and the belief in historical materialism in the necessity of the course of history. If one tries to force people by violence in the direction of a goal, however good it may be, it involves the exercise of power and intolerance; and if this is not under democratic control, it will lead to totalitarianism, be it National Socialist or Stalinist . In this thesis, Popper et al. agree with Ernst Cassirer and Hannah Arendt . All three developed the hypothesis independently in exile.

Popper saw an open society in which democracy is institutionalized as the only rational and therefore sensible alternative. From his point of view, the essential aspect of democracy is neither the rule of the people as sovereign nor the legitimation of the rulers by the people, but that it enables the government to be voted out and guarantees its responsibility.

Piecework social technology

In social philosophy, the problem-solving model is applied analogously. Social institutions are attempts to solve problems. Politics must focus on eliminating the greatest evils. New solutions are tested in social practice. If it has deteriorated or is faulty, it will be rejected or corrected. So that political decisions can be revised, Critical Rationalism recommends an iterative approach in small, manageable steps ( piecemeal social engineering ) when solving social problems .

The critically rational principles therefore also apply in social philosophy. Consistent fallibilism can be found in the position that every social condition can be criticized, since all political opinions and decisions can be tainted with errors. Any dogmatism in politics must therefore be consistently rejected. Methodical rationalism corresponds to the attitude that social conflicts are problems that have to be solved. This requires a critically rational discussion in which the pluralism of opinions is tolerated and observed. The freedom of the individual must therefore be ensured as far as possible. Violence must be avoided as much as possible. In this respect, critical rationalism complements liberalism . Finally, critical realism is reflected in the view that radical utopias lead to oppression and violent revolution. Politicians must therefore concentrate on what is feasible. The greatest social evils always have priority. Therefore, politics must be on the side of the socially and economically weak. This attitude of Popper is known as negative utilitarianism .



The basic ideas of critical rationalism have been programmatically received or used by various political groups. In Germany initially from the liberal side (FDP; Ralf Dahrendorf ), later from the CDU and SPD . The CDU saw the concept of an 'open society' as a basis for defending against excessive ideological and happiness claims. The SPD saw Critical Rationalism as the model for its “creative reformism”. In Germany Federal Chancellor was a. D. Helmut Schmidt (SPD) the best-known self-confessed political supporter of critical rationalism.


In the philosophy of law , the critical rationalism of Reinhold Zippelius and Klaus Adomeit was received as a fundamental method of legal thought and by Bernhard Schlink for the interpretation of the law.


Basic criticism

Prominent critics of fallibilism and advocates of the ultimate justification thesis are Wolfgang Kuhlmann and Karl-Otto Apel , who see the ultimate justification in the implicit prerequisites of communication, above all of argumentative discourse. In the argumentative discourse itself, norms are already accepted which cannot reasonably be disputed and are therefore ultimately justified. Fallibilism, too, recognizes the implicit norms of the argumentation when it argues against the ultimate justification of such norms. The criticism also includes the argument that fallibilism is not applicable to itself. He immunizes himself against criticism by always being able to claim at the end of arguments for a final justification that these arguments are not certain either. The Münchhausen Trilemma, on the other hand, is specifically geared towards logical, especially deductive, conclusions, but does not cover phenomenological (evidence-based), existentialist or pragmatic strategies of justification, i.e. in general what the keywords 'partial', 'circular', 'epistemic' or insufficient reason 'became known.

Jürgen Habermas accused Critical Rationalism of a non-self-reflective and therefore basically positivist attitude, which would stop at an “abstract resolution to unconditional doubt”. He attacked it again and again, and rejected it in particular because of Bartley's realization that it is not comprehensively revisable because of the core logic . Similarly, Niklas Luhmann criticized Critical Rationalism for being “built to be self-reference-aversive” and therefore not applicable to itself. Instead, he pleaded for a theory that can critically refer to itself, even if this creates a theoretical circle, because such a theory, in contrast to critical rationalism, does not depend on motives that cannot be further justified.

Independently of one another, Pavel Tichý and David Miller found that Popper's logical definition of closeness to truth was inadequate. (There is a new proposal from Miller and several from Popper.) Margherita von Brentano criticized the pluralism of critical rationalism as monopluralism . Peter Janich , Lothar Schäfer and Peter Strasser criticized the fact that Popper did not follow the path he had mapped out consistently enough and that he stopped too much at positivistic initial problems.

By Joachim Hofmann a thorough fundamental review comes at critical rationalism in defense of induction, historicism, and rejection of the thesis that an open society is permanently possible. Herbert Keuth has developed a criticism that deals with almost all of Popper's work and consequently with all of the main theses in all areas of critical rationalism. In particular, it is directed against the rehabilitation of correspondence theory and Popper's metaphysical standpoints.

Philosophical critique

The science historian Thomas Kuhn formulated in his work The Structure of Scientific Revolutions the objection that Popper's conceptual model could not explain the historical development of the sciences. He criticized in particular that Popper only treats extraordinary science in the phase of a scientific revolution and not normal science, which takes place within the framework of a generally recognized, established paradigm that changes only during such revolutions. For Kuhn, a paradigm is an instrument for solving problems that can only be questioned when it no longer fulfills its task. He sees real science only when such a paradigm is present and normal science takes place, while any other form can only be seen as embryonic protoscience or as a time of crisis. This is in sharp contradiction to Popper's position, which was exactly the opposite: his epistemology “asserts the permanence of the crisis; if [she] is right, the crisis is the normal state of a highly developed rational science ”. Popper thanked Kuhn for pointing out normal science, but did not consider it a desirable part of research. In his view, it's just bad science.

Lakatos criticized Popper for criticizing and rejecting dogmatic falsificationism in the logic of research , but not making a sharp distinction between the naive and the refined form of methodological falsificationism (this concerns the question of whether a falsified theory must or must be immediately abandoned only when a better one is available). The refined form of methodological falsificationism plays a major role in Lakato's own conception of science in particular. Based on Hegel's thesis that reason is realized in history, he tried to reconcile aspects of the views of Popper and Kuhn. He interpreted the history of science as a story of the rational rise and decline of research programs. On this basis he tried to construct a rational developmental progress from dogmatic to naive and methodological falsificationism to his own point of view and to make his views so self-sufficient. Kuhn was of the opinion that the accusation that Popper was a naive falsificationist was theoretically wrong, but nevertheless one could legitimately see him as such in all practical matters.

Paul Feyerabend was initially himself a representative of critical rationalism. However, he came to the view that breakthroughs in the history of science were always achieved where the currently prevailing methodological rules were ignored. According to Feyerabend, significant scientific findings would have had to be discarded if one had proceeded according to the method of critical rationalism. According to his argumentation, rationalists could not describe the irrational course of the history of science with any general and rational basis, which is why for the rationalist only ' anything goes ' could be considered as a general methodology. Unlike Critical Rationalism, he did not represent a rational, but an anarchist pluralism of methods .

Criticism of the fundamentals of falsification was voiced by so many critics that each argument can be assigned to several or many representatives. The objections concern the question of whether the falsification requires metaphysical assumptions ( O'Hear , Feyerabend, Trusted ); whether all knowledge does not have to arise through observation and deduction (Salmon, Good , O'Hear); whether the acceptance of observation sentences, the requirement for the reproducibility of experiments or the requirement for the strictest possible tests contain non-inductive elements ( Huebner , Newton-Smith , Watkins, Ayer, Hesse , Warnock , Levison , Trusted, O'Hear, Schlesinger , Grünbaum , Musgrave); whether the falsification is not subject to the Goodman paradox , which revolves around the rational distinguishability of two theories that differ only in the future statements ( Vincent , Kyburg , Worrall ); whether induction is not at least necessary for the practical application of theories ( Feigl , Cohen , Salmon, Niiniluoto , Tuomela , Lakatos, Howson , Worrall, Putnam , Jeffrey , O'Hear, Watkins and many more ); whether an inductive guarantee is not necessary that one method is more likely to be closer to the truth than any other (Lakatos); and finally, whether the ' miracle argument ' (the question of how to explain the success of scientific theories) does not speak in favor of inductive conclusions about the veracity of a theory or in favor of probabilistic conclusions about its truth (O'Hear, Newton-Smith et al.)

Otto Neurath held against Popper a “pseudorationalism of falsification”. He was of the opinion that scientific theories cannot be formulated logically and precisely as sentence systems. Instead of falsification, one can only speak of a "shock" of theories in practice. Hilary Putnam took the position that critical rationalism neglects the explanatory function of theories. Adolf Grünbaum tried to show that psychoanalysis , which Popper classified as pseudoscientific according to his delimitation criterion, contrary to this view, was a thoroughly verifiable and thus scientific theory. Instead, he believed that Freud's claims about psychoanalysis, especially the so-called 'Necessary Condition Thesis', had been falsified by clinical findings. He classified it as bad science. Albrecht Wellmer saw Critical Rationalism as a descendant of logical positivism. As an argument, he cited the reduction of epistemology to methodology. David Stove accused Popper of his knowledge skepticism and rejection of the induction of postmodern irrationalism. Martin Gardner took the view that Popper's philosophy of science was irrelevant and impractical and otherwise only replaced existing words suggestively with others.

Socio-theoretical criticism

Popper, who was a socialist in his youth , became known with the publication of The Open Society and its Enemies for his provocative theses on Plato, Hegel and Marx. Ronald B. Levinson , Walter Kaufmann and Maurice Cornforth in particular criticized the sometimes polemical style and selective interpretation . The main critics of the content were Helmut F. Spinner and Robert Ackermann . Expressed further criticism of Popper's social philosophy, in the context of positivism dispute REITs , Theodor W. Adorno and Jürgen Habermas, both of the Critical Theory represented. They were of the opinion that critical rationalism reduced society with its piecemeal social technology to symptomatic phenomena and was therefore positivistic. Critical theory itself took the position that society was built up dialectically from internal contradictions (class antagonisms) and that a reform must begin with the task of tracking down and recognizing these internal contradictions. Critical rationalism, on the other hand, assumes that these contradictions are not rooted in society itself, but merely logical self-contradictions of the totality concept of society. He therefore succumbs to the hopeless attempt to eliminate these contradictions through intellectual reflection on concepts, instead of overcoming the real contradictions (class antagonisms) through political reform. Interestingly, Habermas later tacitly adopted positions from the previously criticized Hans Albert (Albert 2002; Sölter 1996).

Weighing up on Popper's criticism of historicism can be found in Werner Habermehl . Rudolf Thienel criticized Albert's critical-rational position on law .

Fred Eidlin criticized Popper's theory of democracy. It does not lie on the main lines of democratic theoretical discussions, is imperfect and is burdened with considerable gaps and errors. Popper is indifferent to the practical and theoretical problems with which democracy theorists are concerned. He categorically rejects the problem of legitimation, even though it is recognized as a central problem of every political problem. Popper confuses legitimacy ; he does not understand it, as it is right, as a legitimation of state authority, but as an abstract moral principle to justify the uncontrolled exercise of sovereignty .

Response to criticism

The main proponents of critical rationalism have rarely accepted criticism as conclusive and in the majority of cases rejected it. Popper commented on the accusation that he had partly represented a naive falsificationism in the logic of research : "This is of course all nonsense" . Gunnar Andersson has dealt extensively with all variants of this accusation put forward by Kuhn and Lakatos and rejected them as straw man arguments. Still, Popper found that Kuhn's criticism was the most interesting that had been voiced up to that point.

In addition, in the addendum, which is contained in the Open Society from the fourth English edition , Popper clearly distanced himself from the often made assumption that Critical Rationalism is a philosophy of criteria. John Watkins summarized this more sharply and clearly:

Criteria for Scientific Progress? The Popper tradition does not want to know anything about criterion philosophies . If we had appeared armored with criteria, we would have been asked immediately what their authority was. Since we believe that there is no certainty either inside or outside science (apart from logic), we should have admitted that these "criteria" are fallible and that in the event of a conflict between them and science, perhaps our "criteria “Are on the wrong track… Yes, we have no criteria.

(Whether there is security in logic is, however, very controversial in critical rationalism.)

Hans-Joachim Niemann emphasized that an important point of critical rationalism is particularly often overlooked: that observation, although fallible, revisable, selective and theory-laden, is nonetheless unproblematic and can deliver truth. He also warned that the bulk of the accounts and criticism was distorting and often ignored parts of critical rationalism that were essential to the subject.

Bartley explained the many misunderstandings about Critical Rationalism with a central, revolutionary innovation in Popper's rational thinking that makes it so difficult for existing thought schemes to understand it correctly:

The main originality of Popper's position lies in the fact that it is the first non justificational philosophy of criticism in the history of philosophy.

David Miller also made this central mistake in a great many arguments against Critical Rationalism. In other words, they did take fallibilism into account, but not the abandonment of positive, good reasons. Bartley was of the opinion that because of the misunderstandings, Popper’s innovations were not getting the attention they should objectively:

The gulf between Popper's way of doing philosophy and that of the bulk of professional philosophers is as great as that between astronomy and astrology.


Applications of Critical Rationalism:



  • The Philosophy of Karl Popper . In: Paul A. Schilpp (Ed.): Library of Living Philosophers . tape XIV . Open Court Press, La Salle 1974, ISBN 0-87548-141-8 (Two volumes.).
  • Hans-Joachim Niemann: Lexicon of Critical Rationalism , Mohr Siebeck, Tübingen 2004, 423 + XII S., ISBN 3-16-148395-2 .
  • Helmut Seiffert, Gerard Radnitzky (eds.): Handlexikon zur Wissenschaftstheorie , dtv Wissenschaft, Munich 1992, ISBN 3-423-04586-8 .
  • Ian Jarvie, Karl Milford, David Miller (Eds.): Karl Popper: A Centenary Assessment , three volumes, Aldershot; Burlington, VT: Ashgate, 2006, ISBN 0-7546-5387-0 .
  • Burkhard Tuschling, Marie Rischmüller: Critique of Logical Empiricism, pp. 97-104, Duncker & Humblot, Berlin 1983, ISBN 3-428-05455-5 .

To the basics

To social theory

  • Hans Albert: Critical Reason and Human Practice , Reclam, Stuttgart 1977, ISBN 3-15-009874-2 .
  • Albert, Hans: Freedom, Law and Democracy. On the history of the impact of Karl Popper's social philosophy. In: Hubert Kiesewetter, Helmut Zenz (ed.): Karl Poppers Contributions to Ethics , JCB Mohr, Tübingen 2002. pp. 1–16.
  • Karl Popper: The Open Society and its Enemies I . The magic of Plato. Ed .: Hubert Kiesewetter. 8th edition. Tübingen 2003, ISBN 3-16-148068-6 .
  • Karl Popper: The open society and its enemies II . False prophets Hegel, Marx and the consequences. Ed .: Hubert Kiesewetter. 8th edition. Tübingen 2003, ISBN 3-16-148069-4 .
  • Kurt Salamun (Ed.): Morality and Politics from the Perspective of Critical Rationalism , Rodopi, Amsterdam / Atlanta 1991, ISBN 90-5183-203-6 .
  • Ingo Pies , Martin Leschke (eds.): Karl Poppers Critical Rationalism , Mohr Siebeck, Tübingen 1999, ISBN 3-16-147211-X .
  • Arpad A. Sölter: Modernism and cultural criticism. Jürgen Habermas and the legacy of critical theory. Bouvier Verlag, Bonn 1996, ISBN 3-416-02545-8 . [Diss. Univ. Cologne 1993].

To the right

To the philosophy of science

  • David Miller: Critical Rationalism . A restatement and defense. Open Court Publishing Company, 1994, ISBN 0-8126-9198-9 .
  • David Miller: Out Of Error , Ashgate Publishing, 2006, ISBN 0-7546-5068-5 .
  • Alan Musgrave: Everyday knowledge, science and skepticism , Mohr Siebeck / UTB, Tübingen 1993, ISBN 3-8252-1740-X .
  • Karl Popper: The two basic problems of epistemology . Tübingen 1979, ISBN 3-16-838212-4 .
  • Karl Popper: Logic of Research . 11th edition. Tübingen 2005, ISBN 3-16-148410-X .
  • Hans Günther Russ: Theory of Science, Epistemology and the Search for Truth. An introduction , Kohlhammer, Stuttgart 2004, ISBN 3-17-018190-4 .
  • Gunnar Andersson: Critique and History of Science. Lakatos' and Feyerabend's Critique of Critical Rationalism. Mohr Siebeck, Tübingen 1988, ISBN 3-16-945308-4 .

To ethics

  • Hans Albert: Ethics and Meta-Ethics . In: Ders .: Construction and Criticism , 2nd ed., Hoffmann and Campe, Hamburg undated, pp. 127–167.
  • Christoph Lütge: Critical-rationalistic ethics . In: Ethica 10, 4 (2002), pp. 377-405.
  • Christoph Lütge: What does the critical-rationalist ethics do? In: Ethica 11, 4 (2003), pp. 389-409.
  • Hans-Joachim Niemann: The strategy of reason - problem-solving reason, rational metaphysics and critical-rational ethics , 2nd improved and expanded edition, Mohr Siebeck, Tübingen 2008, ISBN 978-3-16-149878-7 .
  • Hans-Joachim Niemann: On the limits of tolerance and 'objective tolerance' as an instrument to minimize violence . In: Eric Hilgendorf (Ed.): Science, Religion and Law - Hans Albert for his 85th birthday , Berlin (LOGOS) 2006, pp. 313–338.
  • Hans-Joachim Niemann: How objective can ethics be? In: Enlightenment and Criticism 5 (2001), pp. 23–41.

Web links

Wikibooks: Study Guide Hans Albert  - Learning and Teaching Materials
Wikibooks: Be sensible! - A crash course  - learning and teaching materials


  1. Karl Popper: The open society and its enemies II . False prophets Hegel, Marx and the consequences. Ed .: Hubert Kiesewetter. 8th edition. Tübingen 2003, ISBN 3-16-148069-4 , pp. 281 .
  2. ^ Karl Popper: All life is problem solving , Piper, 1994, ISBN 3-492-22300-1 .
  3. Karl Popper: In search of a better world , Piper, 1984, ISBN 3-492-20699-9 .
  4. Karl Popper: The Open Society and its Enemies I . The magic of Plato. Ed .: Hubert Kiesewetter. 8th edition. Tübingen 2003, ISBN 3-16-148068-6 , pp. 269 .
  5. Hans Albert: Variants of Critical Rationalism. In: Jan M. Böhm, Heiko Holweg, Claudia Hoock (eds.): Karl Poppers critical rationalism today. On the topicality of critical-rational philosophy of science , Mohr Siebeck, Tübingen 2002, pp. 3–22.
  6. ^ John R. Wettersten: The Roots of Critical Rationalism , Amsterdam / Atlanta 1992, p. 9 f.
  7. Popper Archives, Fascicle 297.11, quoted by David Miller: Sir Karl Raimund Popper , CH, FBA 28 July 1902--17 September 1994 .: Elected FRS 1976 . In: Biographical Memoirs of Fellows of the Royal Society . tape 43 , 1997, pp. 369 , doi : 10.1098 / rsbm.1997.0021 (English).
  8. ^ Karl Popper, John C. Eccles: The self and its brain , Springer, 1977, ISBN 0-387-08307-3 , p. VIII.
  9. ^ Edward Zerin: Karl Popper On God: The Lost Interview. Skeptic 6 (2) (1998).
  10. W. W. Bartley: Deep-Est , The New York Review of Books 26 (9) (May 31, 1979).
  11. ^ Hans-Albert-Institut - For a critical-rational politics. Accessed December 26, 2020 (German).
  12. ^ David Miller: Critical Rationalism . A restatement and defense. Open Court Publishing Company, 1994, ISBN 0-8126-9198-9 . 2.2i.
  13. ^ Karl Popper: Objective knowledge . 2nd Edition. Hamburg 1974, ISBN 3-455-09088-5 . Cape. 2
  14. ^ William W. Bartley: Escape into engagement . Mohr Siebeck, 1987, ISBN 3-16-945130-8 . Here: Appendix 2, Section 8.
  15. ^ David Miller: Critical Rationalism . A restatement and defense. Open Court Publishing Company, 1994, ISBN 0-8126-9198-9 . 2.2c.
  16. ^ The Philosophy of Karl Popper . In: Paul A. Schilpp (Ed.): Library of Living Philosophers . tape XIV . Open Court Press, La Salle 1974, ISBN 0-87548-141-8 , pp. 1041 and 1043 (two volumes.).
  17. Karl Popper: Logic of Research . 11th edition. Tübingen 2005, ISBN 3-16-148410-X . Section * IX, point 12.
  18. ^ William W. Bartley: (link not available). In: Philosophia 11, 1-2 (1982), Section XXVI.
  19. ^ David Miller: Critical Rationalism . A restatement and defense. Open Court Publishing Company, 1994, ISBN 0-8126-9198-9 . 6.3
  20. ^ David Miller: Critical Rationalism . A restatement and defense. Open Court Publishing Company, 1994, ISBN 0-8126-9198-9 . Chapter 3.
  21. ^ The Philosophy of Karl Popper . In: Paul A. Schilpp (Ed.): Library of Living Philosophers . tape XIV . Open Court Press, La Salle 1974, ISBN 0-87548-141-8 , pp. 69 (two volumes.).
  22. ^ David Miller: Critical Rationalism . A restatement and defense. Open Court Publishing Company, 1994, ISBN 0-8126-9198-9 . 6.3.
  23. Compare Hans Albert: Critique of pure epistemology , Mohr Siebeck, Tübingen 1987, section 16, as well as the entry 'Minimallogik' in Niemann, Lexikon des Kritischen Rationalismus (2004/2006).
  24. ^ A b Karl Popper: Logic of Research . 11th edition. Tübingen 2005, ISBN 3-16-148410-X . Section 10.
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This article was added to the list of excellent articles on August 16, 2007 in this version .