Critical rationalism

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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]

Philosophy intellectual and/or logical study of general and fundamental problems

Philosophy is the study of general and fundamental problems concerning matters such as existence, knowledge, values, reason, mind, and language. The term was probably coined by Pythagoras. Philosophical methods include questioning, critical discussion, rational argument, and systematic presentation. Classic philosophical questions include: Is it possible to know anything and to prove it? What is most real? Philosophers also pose more practical and concrete questions such as: Is there a best way to live? Is it better to be just or unjust? Do humans have free will?

Karl Popper Austrian-British philosopher of science

Sir Karl Raimund Popper was an Austrian-British philosopher and professor.

<i>The Logic of Scientific Discovery</i> book by Karl Popper

The Logic of Scientific Discovery is a 1959 book about the philosophy of science by Karl Popper. Popper rewrote his book in English from the 1934 German original, titled Logik der Forschung. Zur Erkenntnistheorie der modernen Naturwissenschaft, which literally translates as, "Logic of Research: On the Epistemology of Modern Natural Science"'.


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").

Knowledge is a familiarity, awareness, or understanding of someone or something, such as facts, information, descriptions, or skills, which is acquired through experience or education by perceiving, discovering, or learning.

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.

In philosophy, rationalism is the epistemological view that "regards reason as the chief source and test of knowledge" or "any view appealing to reason as a source of knowledge or justification". More formally, rationalism is defined as a methodology or a theory "in which the criterion of the truth is not sensory but intellectual and deductive".

Age of Enlightenment European cultural movement of the 18th century

The Age of Enlightenment was an intellectual and philosophical movement that dominated the world of ideas in Europe during the 18th century, the "Century of Philosophy".

Verificationism, also known as the verification idea or the verifiability criterion of meaning, is the philosophical doctrine that only statements that are empirically verifiable are cognitively meaningful, or else they are truths of logic (tautologies).

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:[ citation needed ] 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

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. Black Swans.jpg
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.

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Epistemology A branch of philosophy concerned with the nature and scope of knowledge

Epistemology is the branch of philosophy concerned with the theory of knowledge.

Falsifiability the possibility of a statement to be proven wrong

A statement, hypothesis, or theory has falsifiability 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.

Logical positivism and logical empiricism, which together formed neopositivism, was a movement in Western philosophy whose central thesis was verificationism, a theory of knowledge which asserted that only statements verifiable through empirical observation are meaningful. The movement flourished in the 1920s and 1930s in several European centers.

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.

The problem of induction is the philosophical question of whether inductive reasoning leads to knowledge understood in the classic philosophical sense, highlighting the apparent lack of justification for:

  1. Generalizing about the properties of a class of objects based on some number of observations of particular instances of that class or
  2. Presupposing that a sequence of events in the future will occur as it always has in the past. Hume called this the principle of uniformity of nature.

In philosophy and models of scientific inquiry, postpositivism is a metatheoretical stance that critiques and amends positivism. While positivists emphasize independence between the researcher and the researched person, postpositivists accept that theories, background, knowledge and values of the researcher can influence what is observed. Postpositivists pursue objectivity by recognizing the possible effects of biases. While positivists emphasize quantitative methods, postpositivists consider both quantitative and qualitative methods to be valid approaches.

Hans Albert German philosopher

Hans Albert is a German philosopher. Born in Cologne, he lives in Heidelberg.

Pancritical rationalism, 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 philosophy of science based on the view that information derived from scientific observation is the exclusive source of all authoritative knowledge

Positivism is a philosophical theory stating that certain ("positive") knowledge is based on natural phenomena and their properties and relations. Thus, information derived from sensory experience, interpreted through reason and logic, forms the exclusive source of all certain knowledge. Positivism holds that valid knowledge is found only in this a posteriori knowledge.

Broadly speaking, fallibilism 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.

Münchhausen trilemma A thought experiment used to demonstrate the impossibility of proving any truth

In epistemology, the Münchhausen trilemma is a thought experiment used to demonstrate the impossibility of proving any truth, even in the fields of logic and mathematics. If it is asked how any knowledge is known to be true, proof may be provided. Yet that same question can be asked of the proof, and any subsequent proof. The Münchhausen trilemma is that there are only three options when providing proof in this situation:

Positivism dispute Political and philosophical dispute

The positivism dispute was a political-philosophical dispute between the critical rationalists and the Frankfurt School 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 as 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.

Outline of epistemology Overview of and topical guide to epistemology

The following outline is provided as an overview of and topical guide to epistemology:

Epistemology or theory of knowledge is the branch of philosophy concerned with the nature and scope (limitations) of knowledge. It addresses the questions "What is knowledge?", "How is knowledge acquired?", "What do people know?", "How do we know what we know?", and "Why do we know what we know?". Much of the debate in this field has focused on analyzing the nature of knowledge and how it relates to similar notions such as truth, belief, and justification. It also deals with the means of production of knowledge, as well as skepticism about different knowledge claims.

Explanatory power is the ability of a hypothesis or theory to effectively explain the subject matter it pertains to. The opposite of explanatory power is explanatory impotence.

Bold hypothesis is a concept in the philosophy of science of Karl Popper, first explained in his debut The Logic of Scientific Discovery (1935) and subsequently elaborated in writings such as Conjectures and Refutations: The Growth of Scientific Knowledge (1963). The concept is nowadays widely used in the philosophy of science and in the philosophy of knowledge. It is also used in the social and behavioural sciences.


  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. 1 2 3 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"

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