Critical rationalism

Critical rationalism is an epistemological philosophy advanced by Karl Popper. Popper wrote about critical rationalism in his works: The Logic of Scientific Discovery,[1] The Open Society and its Enemies,[2] Conjectures and Refutations,[3] The Myth of the Framework,[4] and Unended Quest.[5] Ernest Gellner is another notable proponent of this approach.[6]

Criticism, not support

Critical rationalists hold that scientific theories and any other claims to knowledge can and should be rationally criticized, and (if they have empirical content) can and should be subjected to tests which may falsify them. Thus claims to knowledge may be contrastingly and normatively evaluated. They are either falsifiable and thus empirical (in a very broad sense), or not falsifiable and thus non-empirical. Those claims to knowledge that are potentially falsifiable can then be admitted to the body of empirical science, and then further differentiated according to whether they are retained or are later actually falsified. If retained, further differentiation may be made on the basis of how much subjection to criticism they have received, how severe such criticism has been, and how probable the theory is, with the least[7] probable theory that still withstands attempts to falsify it being the one to be preferred. That it is the least[7] probable theory that is to be preferred is one of the contrasting differences between critical rationalism and classical views on science, such as positivism, who hold that one should instead accept the most probable theory. (The least probable theory is the one with the highest information content and most open to future falsification.) Critical Rationalism as a discourse positioned itself against what its proponents took to be epistemologically relativist philosophies, particularly post-modernist or sociological approaches to knowledge. Critical rationalism has it that knowledge is objective (in the sense of being embodied in various substrates and in the sense of not being reducible to what humans individually "know"), and also that truth is objective (exists independently of social mediation or individual perception, but is "really real").

However, this contrastive, critical approach to objective knowledge is quite different from more traditional views that also hold knowledge to be objective. (These include the classical rationalism of the Enlightenment, the verificationism of the logical positivists, or approaches to science based on induction, a supposed form of logical inference which critical rationalists reject, in line with David Hume.) For criticism is all that can be done when attempting to differentiate claims to knowledge, according to the critical rationalist. Reason is the organon of criticism, not of support; of tentative refutation, not of proof.

Supposed positive evidence (such as the provision of "good reasons" for a claim, or its having been "corroborated" by making successful predictions) actually does nothing to bolster, support, or prove a claim, belief, or theory.

In this sense, critical rationalism turns the normal understanding of a traditional rationalist, and a realist, on its head. Especially the view that a theory is better if it is less likely to be true is in direct opposition to the traditional positivistic view, which holds that one should seek for theories that have a high probability.[7] Popper notes that this "may illustrate Schopenhauer's remark that the solution of a problem often first looks like a paradox and later like a truism". Even a highly unlikely theory that conflicts current observation (and is thus false, like "all swans are white") must be considered to be better than one which fits observations perfectly, but is highly probable (like "all swans have a color"). This insight is the crucial difference between naive falsificationism and critical rationalism. The lower probability theory is favoured by critical rationalism because the higher the informative content of a theory the lower will be its probability, for the more information a statement contains, the greater will be the number of ways in which it may turn out to be false. The rationale behind this is simply to make it as easy as possible to find out whether the theory is false so that it can be replaced by one that is closer to the truth. It is not meant as a concession to justificatory epistemology, like assuming a theory to be "justifiable" by asserting that it is highly unlikely and yet fits observation.

Critical rationalism rejects the classical position that knowledge is justified true belief; it instead holds the exact opposite: That, in general, knowledge is unjustified untrue unbelief. It is unjustified because of the non-existence of good reasons. It is untrue, because it usually contains errors that sometimes remain unnoticed for hundreds of years. And it is not belief either, because scientific knowledge, or the knowledge needed to build a plane, is contained in no single person's mind. It is only available as the content of books.


William Warren Bartley compared critical rationalism to the very general philosophical approach to knowledge which he called justificationism, the view that scientific theories can be justified. Most justificationists do not know that they are justificationists. Justificationism is what Popper called a "subjectivist" view of truth, in which the question of whether some statement is true, is confused with the question of whether it can be justified (established, proven, verified, warranted, made well-founded, made reliable, grounded, supported, legitimated, based on evidence) in some way.

According to Bartley, some justificationists are positive about this mistake. They are naïve rationalists, and thinking that their knowledge can indeed be founded, in principle, it may be deemed certain to some degree, and rational.

Other justificationists are negative about these mistakes. They are epistemological relativists, and think (rightly, according to the critical rationalist) that you cannot find knowledge, that there is no source of epistemological absolutism. But they conclude (wrongly, according to the critical rationalist) that there is therefore no rationality, and no objective distinction to be made between the true and the false.

By dissolving justificationism itself, the critical rationalist (a proponent of non-justificationism)[8] regards knowledge and rationality, reason and science, as neither foundational nor infallible, but nevertheless does not think we must therefore all be relativists. Knowledge and truth still exist, just not in the way we thought.

The pitfalls of justificationism and positivism

Black Swans
Are all swans white? The classical view of the philosophy of science is that it is the goal of science to “prove” such hypotheses or induce them from observational data. This seems hardly possible, since it would require us to infer a general rule from a number of individual cases, which is logically inadmissible. However, if we find one single black swan, logic allows us to conclude that the statement that all swans are white is false. Falsificationism thus strives for questioning, for falsification, of hypotheses instead of proving them.

The rejection of "positivist" approaches to knowledge occurs due to various pitfalls that positivism falls into.

1. The naïve empiricism of induction was shown to be illogical by Hume. A thousand observations of some event A coinciding with some event B does not allow one to logically infer that all A events coincide with B events. According to the critical rationalist, if there is a sense in which humans accrue knowledge positively by experience, it is only by pivoting observations off existing conjectural theories pertinent to the observations, or off underlying cognitive schemas which unconsciously handle perceptions and use them to generate new theories. But these new theories advanced in response to perceived particulars are not logically "induced" from them. These new theories may be wrong. The myth that we induce theories from particulars is persistent because when we do this we are often successful, but this is due to the advanced state of our evolved tendencies. If we were really "inducting" theories from particulars, it would be inductively logical to claim that the sun sets because I get up in the morning, or that all buses must have drivers in them (if you've never seen an empty bus).

2. Popper and David Miller showed in 1983[9] that evidence supposed to partly support a hypothesis can, in fact, only be neutral to, or even be counter-supportive of the hypothesis.

3. Related to the point above, David Miller,[10] attacks the use of "good reasons" in general (including evidence supposed to support the excess content of a hypothesis). He argues that good reasons are neither attainable, nor even desirable. Basically, Miller asserts that all arguments purporting to give valid support for a claim are either circular or question-begging. That is, if one provides a valid deductive argument (an inference from premises to a conclusion) for a given claim, then the content of the claim must already be contained within the premises of the argument (if it is not, then the argument is ampliative and so is invalid). Therefore, the claim is already presupposed by the premises, and is no more "supported" than are the assumptions upon which the claim rests, i.e. begging the question.

See also



  1. ^ Popper, Karl (2002) [1959]. The Logic of Scientific Discovery (2nd English ed.). New York, NY: Routledge Classics. ISBN 0-415-27844-9. OCLC 59377149.
  2. ^ Popper, K., The Open Society and Its Enemies, Princeton University Press, 2013, p.435.
  3. ^ Popper, K., Conjectures and Refutations: The Growth of Scientific Knowledge, Routledge, 2014, p. 34.
  4. ^ Popper, K., The Myth of the Framework: In Defence of Science and Rationality, Routledge, 2014, p. xii.
  5. ^ Popper, K., Unended Quest: An Intellectual Autobiography, Routledge, 2005, p. 132.
  6. ^ Stirling, Paul (9 November 1995). "Ernest Gellner Obituary". The Daily Telegraph.
  7. ^ a b c Popper, Karl (2002) [1959]. The Logic of Scientific Discovery (2nd English ed.). New York, NY: Routledge Classics. ISBN 0-415-27844-9. OCLC 59377149., section 43, especially footnote *1 and *2
  8. ^ "Karl Popper and Critical Rationalism". Internet Encyclopedia of Philosophy.
  9. ^ Nature 302, April 21, "A Proof of the Impossibility of Inductive Probability"
  10. ^ In his Critical Rationalism: A Restatement and Defence, Chapter 3 "A Critique of Good Reasons"

Further reading

  • Maxwell, Nicholas (2017) Karl Popper, Science and Enlightenment, UCL Press, London. Free online.
  • Niemann, Hans-Joachim. Lexikon des Kritischen Rationalismus, (Encyclopaedia of Critical Rationalism), Tübingen (Mohr Siebeck) 2004, ISBN 3-16-148395-2. More than a thousand headwords about critical rationalism, the most important arguments of K.R. Popper and H. Albert, quotations of the original wording. Edition for students in 2006, ISBN 3-16-149158-0.
  • Parusniková, Zuzana & Robert S. Cohen (2009). Rethinking Popper, Description and contents. Springer.
  • Reinhold Zippelius. Die experimentierende Methode im Recht (trial and error in jurisprudence), (Academy of Science, Mainz) 1991, ISBN 3-515-05901-6

External links

Adela Cortina

Adela Cortina is a Spanish philosopher born in Valencia, Spain.

After getting her degree of philosophy and letters in the University of Valencia, she entered the metaphysics department in 1969. In 1976, she defended her doctorate's thesis, about God in the Kantian transcendental philosophy, and taught for some time in middle-grade institutes.

A research grant allowed her to visit the University of Munich, where she came in contact with critical rationalism, pragmatism, Marxist ethics and more specifically, with the philosophy of Jürgen Habermas and Karl-Otto Apel. Upon reentering academia in Spain, she oriented her research efforts into ethics.

In 1981, she entered the philosophy department of her alma mater, the University of Valencia. She is a frequent contributor to El Pais.

David Miller (philosopher)

David W. Miller (born 19 August 1942, Watford) is an English philosopher and prominent exponent of critical rationalism. He taught in the Department of Philosophy at the University of Warwick in Coventry, UK. where he is Reader in Philosophy. He has been Honorary Treasurer of the British Society for the Philosophy of Science

He was educated at Woodbridge School and Peterhouse, Cambridge. In 1964 he began to study Logic and Scientific Method at the London School of Economics. Soon afterwards he became one of Karl Popper's research assistants. In a series of papers in the 1970s, Miller and others uncovered defects in Popper's formal definition of verisimilitude, previously a mostly ignored aspect of Popper's theory. A substantial literature developed in the two decades following, including papers by Miller, to assess the remediability of Popper's approach.

Miller's Critical Rationalism: A Restatement and Defence is an attempt to expound, defend, and extend an approach to scientific knowledge identified with Popper. A central, "not quite original", thesis is that rationality does not depend on good reasons. Rather, it is better off without them, especially as they are unobtainable and unusable.

Ernest Gellner

Ernest André Gellner (9 December 1925 – 5 November 1995) was a British-Czech philosopher and social anthropologist described by The Daily Telegraph, when he died, as one of the world's most vigorous intellectuals, and by The Independent as a "one-man crusader for critical rationalism".His first book, Words and Things (1959), prompted a leader in The Times and a month-long correspondence on its letters page over his attack on linguistic philosophy. As the Professor of Philosophy, Logic and Scientific Method at the London School of Economics for 22 years, the William Wyse Professor of Social Anthropology at the University of Cambridge for eight years, and head of the new Centre for the Study of Nationalism in Prague, Gellner fought all his life—in his writing, teaching and political activism—against what he saw as closed systems of thought, particularly communism, psychoanalysis, relativism and the dictatorship of the free market. Among other issues in social thought, modernization theory and nationalism were two of his central themes, his multicultural perspective allowing him to work within the subject-matter of three separate civilizations: Western, Islamic, and Russian. He is considered one of the leading theoreticians on the issue of nationalism.


Broadly speaking, fallibilism (from Medieval Latin: fallibilis, "liable to err") is the philosophical claim that no belief can have justification which guarantees the truth of the belief. However, not all fallibilists believe that fallibilism extends to all domains of knowledge.


A statement, hypothesis, or theory has falsifiability (or is falsifiable) if it is contradicted by a basic statement, which, in an eventual successful or failed falsification, must respectively correspond to a true or hypothetical observation. For example, the claim "all swans are white and have always been white" is falsifiable since it is contradicted by this basic statement: "In 1697, during the Dutch explorer Willem de Vlamingh expedition, there were black swans on the shore of the Swan River in Australia", which in this case is a true observation. The concept is also known by the terms refutable and refutability.

The concept was introduced by the philosopher of science Karl Popper. He saw falsifiability as the logical part and the cornerstone of his scientific epistemology, which sets the limits of scientific inquiry. He proposed that statements and theories that are not falsifiable are unscientific. Declaring an unfalsifiable theory to be scientific would then be pseudoscience.

Hans-Joachim Niemann

Hans Joachim Niemann (born in 1941 in Kiel), is a German philosopher who has developed the methods of critical rationalism for applying them in the fields of metaphysics and ethics.

Hans Albert

Hans Albert (born 8 February 1921) is a German philosopher. Born in Cologne, he lives in Heidelberg.

His fields of research are Social Sciences and General Studies of Methods. He is a critical rationalist, paying special attention to rational heuristics. He is a strong critic of the continental hermeneutic tradition coming from Heidegger and Gadamer.

Heinrich Gottlieb Tzschirner

Heinrich Gottlieb Tzschirner (14 November 1778 – 17 February 1828) was a German Protestant theologian born in Mittweida, Saxony.

He studied theology at the University of Leipzig, receiving his habilitation in 1800 with assistance from Dresden examinator Franz Volkmar Reinhard (1753-1812). For a period of time he worked as a private lecturer at the University of Wittenberg, and following his father's death became deacon in his home town of Mittweida. In 1805 he was appointed professor of theology at Wittenberg, later returning to Leipzig (1809), where in 1811 he became rector of the university.

In 1813 he joined the Saxon Army as a chaplain during the Napoleonic Wars. He returned to Leipzig the following year, subsequently becoming archdeacon of St. Thomas Church and superintendent of the Diocese of Leipzig.

As a theologian, Tzschirner was an advocate of ethical and critical rationalism, believing that common sense morality was the supreme principle of Christianity. In one of his better known works, Protestantismus and Katholicismus aus dem Standpunkte der Politik betrachlet, he staunchly defended the Protestant cause versus Catholicism. In addition to his own written works, he continued publication of Johann Matthias Schröckh's Christliche Kirchengeschichte seit der Reformation (Church History since the Reformation) after Schröckh's death in 1808.

John W. N. Watkins

John William Nevill Watkins (31 July 1924, Woking, Surrey – 26 July 1999, Salcombe, Devon) was an English philosopher, a professor at the London School of Economics from 1966 until his retirement in 1989 and a prominent proponent of critical rationalism.


Jurisprudence or legal theory is the theoretical study of law, principally by philosophers but, from the twentieth century, also by social scientists. Scholars of jurisprudence, also known as jurists or legal theorists, hope to obtain a deeper understanding of legal reasoning, legal systems, legal institutions, and the role of law in society.Modern jurisprudence began in the 18th century and was focused on the first principles of natural law, civil law, and the law of nations. General jurisprudence can be divided into categories both by the type of question scholars seek to answer and by the theories of jurisprudence, or schools of thought, regarding how those questions are best answered. Contemporary philosophy of law, which deals with general jurisprudence, addresses problems internal to law and legal systems and problems of law as a social institution that relates to the larger political and social context in which it exists.This article addresses three distinct branches of thought in general jurisprudence. Ancient natural law is the idea that there are rational objective limits to the power of legislative rulers. The foundations of law are accessible through reason, and it is from these laws of nature that human laws gain whatever force they have. Analytic jurisprudence (Clarificatory jurisprudence) rejects natural law's fusing of what law is and what it ought to be. It espouses the use of a neutral point of view and descriptive language when referring to aspects of legal systems. It encompasses such theories of jurisprudence as "legal positivism", which holds that there is no necessary connection between law and morality and that the force of law comes from basic social facts; and "legal realism", which argues that the real-world practice of law determines what law is, the law having the force that it does because of what legislators, lawyers, and judges do with it. Normative jurisprudence is concerned with "evaluative" theories of law. It deals with what the goal or purpose of law is, or what moral or political theories provide a foundation for the law. It not only addresses the question "What is law?", but also tries to determine what the proper function of law should be, or what sorts of acts should be subject to legal sanctions, and what sorts of punishment should be permitted.

Karl Popper

Sir Karl Raimund Popper (28 July 1902 – 17 September 1994) was an Austrian philosopher and professor.Generally regarded as one of the 20th century's greatest philosophers of science, Popper is known for his rejection of the classical inductivist views on the scientific method in favour of empirical falsification. A theory in the empirical sciences can never be proven, but it can be falsified, meaning that it can and should be scrutinised by decisive experiments. Popper is also known for his opposition to the classical justificationist account of knowledge, which he replaced with critical rationalism, namely "the first non-justificational philosophy of criticism in the history of philosophy".In political discourse, he is known for his vigorous defence of liberal democracy and the principles of social criticism that he came to believe made a flourishing open society possible. His political philosophy embraces ideas from all major democratic political ideologies and attempts to reconcile them, namely socialism/social democracy, libertarianism/classical liberalism and conservatism.

List of philosophies

Philosophical schools of thought and philosophical movements.

Pancritical rationalism

Pancritical rationalism (literally "criticism of all things", from pan-, "all", also known as PCR), also called comprehensively critical rationalism (CCR), is a development of critical rationalism and panrationalism originated by William Warren Bartley in his book The Retreat to Commitment. PCR attempts to work around the problem of ultimate commitment or infinite regress by decoupling criticism and justification. A pancritical rationalist holds all positions open to criticism, including PCR itself. Such a position in principle never resorts to appeal to authority for justification of stances, since all authorities are held to be intrinsically fallible.

Positivism dispute

The positivism dispute (German: Positivismusstreit) was a political-philosophical dispute between the critical rationalists (Karl Popper, Hans Albert) and the Frankfurt School (Theodor Adorno, Jürgen Habermas) in 1961, about the methodology of the social sciences. It grew into a broad discussion within German sociology from 1961 to 1969. The naming itself is controversial, since it was the Frankfurt School proponents who accused the critical rationalists of being positivists—while the latter considered themselves to be opponents of positivism. On the political level, it was a dispute between the leftist Frankfurt School proponents supporting revolution, and the allegedly bourgeois critical rationalists supporting reform as the method to be preferred to change society.

Rationalism (disambiguation)

Rationalism may refer to:

Rationalism, a philosophical position, theory, or view that reason is the source of knowledge

Rationalism (architecture), a term applied to a number of architectural movements

Rationalism (international relations), a political perspective on the international system

Rationalism (theology), philosophical Rationalism applied in theology

Critical rationalism, an epistemological philosophy advanced by Karl Raimund Popper

Economic rationalism, an Australian term in discussion of microeconomic policy

Pancritical rationalism, a theory by William Warren Bartley developed from panrationalism and critical rationalism

Progressive rationalism

Theory of justification

The theory of justification is a part of epistemology that attempts to understand the justification of propositions and beliefs. Epistemologists are concerned with various epistemic features of belief, which include the ideas of justification, warrant, rationality, and probability. Loosely speaking, justification is the reason that someone (properly) holds a belief.

When a claim is in doubt, justification can be used to support the claim and reduce or remove the doubt. Justification can use empiricism (the evidence of the senses), authoritative testimony (the appeal to criteria and authority), or reason.

Unended Quest

Unended Quest: An Intellectual Autobiography (1976 [2002]) is a book by Karl Popper.A 2002 edition came out re-paginated with more words per page, two postscripts, and updated bibliography.The work first appeared with the title "Autobiography of Karl Popper" in The Philosophy of Karl Popper (1974) from the Library of Living Philosophers series.The book chronicles Popper's life from the beginning, including wider implications he drew from his experiences. In chapter 1, "Omniscience and Fallibility," for example, he describes his apprenticeship to a cabinetmaker while he was a university student. His master invited him to ask anything he liked, because, with due modesty, the master claimed to know everything. From his omniscient master, Popper writes that he became a disciple of Socrates and learned more about the theory of knowledge, including how little he knew, than from his university teachers.

Other thematic chapter subjects include music, education, philosophical problems Popper encountered, and his differences from other philosophers, whether earlier or contemporary. These are woven into an account of events in his life and research programmes that he developed. For example, Chapter 24 discusses 2 of his best-known works, The Open Society and Its Enemies and The Poverty of Historicism, and the origins of 'critical rationalism' to describe the approach he espoused.

W. W. Bartley III

William Warren Bartley III (October 2, 1934 – February 5, 1990), known as W. W. Bartley III, was an American philosopher specializing in 20th century philosophy, language and logic, and the Vienna Circle.

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