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Karl Popper

Karl Popper

Overview
Sir Karl Raimund Popper, CH
Order of the Companions of Honour
The Order of the Companions of Honour is an order of the Commonwealth realms. It was founded by King George V in June 1917, as a reward for outstanding achievements in the arts, literature, music, science, politics, industry, or religion....

, FRS, FBA (28 July 1902 – 17 September 1994) was an Austrian and British philosopher and a professor at the London School of Economics
London School of Economics
The London School of Economics and Political Science, commonly referred to as the London School of Economics or LSE, is a specialist constituent college of the University of London in London, England....

. He is considered one of the most influential philosophers of science
Philosophy of science
The philosophy of science is concerned with the assumptions, foundations, and implications of science. The field is defined by an interest in one of a set of "traditional" problems or an interest in central or foundational concerns in science...

 of the 20th century, and also wrote extensively on social and political philosophy. Popper is known for repudiating the classical observationalist/inductivist
Inductivism
In the philosophy of science inductivism exists both in a classical naive version, which has been highly influential, and in various more sophisticated versions...

 account of scientific method
Scientific method
Scientific method refers to a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. To be termed scientific, a method of inquiry must be based on gathering observable, empirical and measurable evidence subject to specific...

 by advancing empirical falsification
Falsifiability
Falsifiability is the logical possibility that an assertion can be shown false by an observation or a physical experiment. That something is "falsifiable" does not mean it is false; rather, that if it is false, then this can be shown by observation or experiment. Falsifiability is an important...

 instead; for his opposition to the classical justificationist account of knowledge which he replaced with critical rationalism
Critical rationalism
Critical rationalism is an epistemological philosophy advanced by Karl Popper. Popper wrote about critical rationalism in his works, The Open Society and its Enemies Volume 2, and Conjectures and Refutations.- Criticism, not support :...

, "the first non justificational philosophy of criticism in the history of philosophy", and for his vigorous defense of liberal democracy
Liberal democracy
Liberal democracy is the dominant form of democracy in the 21st century. During the Cold War, liberal democracies were contrasted with the Communist People's Republics or "Popular Democracies", which claimed an alternative conception of democracy...

 and the principles of social criticism
Social criticism
Social criticism analyzes social structures which are seen as flawed and aims at practical solutions by specific measures, radical reform or even revolutionary change....

 that he came to believe made a flourishing "open society
Open society
The open society is a concept originally developed by philosopher Henri Bergson. In open societies, government is responsive and tolerant, and political mechanisms are transparent and flexible....

" possible.

Karl Popper was born in Vienna
Vienna
Vienna is the capital of the Republic of Austria and also one of the nine states of Austria. Vienna is Austria's primary city, with a population of about 1.7 million , and is by far the largest city in Austria, as well as its cultural, economic, and political centre. It is the 10th largest city by...

 (then in Austria-Hungary
Austria-Hungary
Austria–Hungary, also known as the Austro-Hungarian Empire, the Dual Monarchy or the k.u.k. Monarchy, or Dual State, was a monarchic union between the crowns of the Austrian Empire and the Kingdom of Hungary in Central Europe...

) in 1902, to middle-class parents of assimilated Jewish origins, both of whom had converted to Christianity
Christianity
Christianity is a monotheistic religion based on the life and teachings of Jesus of Nazareth as presented by the revelations in the New Testament....

.

Karl's father Dr Simon Siegmund Carl Popper was a lawyer from Prague
Prague
Prague is the capital and largest city of the Czech Republic. Nicknames for Prague have included "the mother of cities" , "city of a hundred spires", or Stověžatá Praha in Czech and "the golden city" or Zlaté město in Czech.Situated on the River Vltava in central Bohemia, Prague has been the...

, and mother Jenny Schiff was of Silesian
Silesian
Silesian or Upper Silesian is a Slavic language spoken in the region of Silesia. The ISO 639-3 language code is szl.- Distribution :...

and Hungarian
Hungarian
Hungarian may refer to:* Hungary, a country in Central Europe* Kingdom of Hungary, state of Hungary, existing from 1000 to 1946* Hungarian people, the ethnic group primarily associated with Hungary...

 descent.

Popper received a Lutheran upbringing and was educated at the University of Vienna
University of Vienna
The University of Vienna is a public university located in Vienna, Austria. It was founded by Duke Rudolph IV in 1365 and is, therefore, the oldest university in the German-speaking world and one of the largest in Central Europe.-History:...

.
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Quotations

You can choose whatever name you like for the two types of government. I personally call the type of government which can be removed without violence "democracy", and the other "tyranny".

As quoted in Freedom: A New Analysis (1954) by Maurice William Cranston, p. 112

Piecemeal social engineering resembles physical engineering in regarding the ends as beyond the province of technology. (All that technology may say about ends is whether or not they are compatible with each other or realizable.)

The Poverty of Historicism (1957) Ch. 22 The Unholy Alliance with Utopianism

If we are uncritical we shall always find what we want: we shall look for, and find, confirmations, and we shall look away from, and not see, whatever might be dangerous to our pet theories. In this way it is only too easy to obtain what appears to be overwhelming evidence in favor of a theory which, if approached critically, would have been refuted.

The Poverty of Historicism (1957) Ch. 29 The Unity of Method

Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory nor the problem which it was intended to solve.

Objective Knowledge: An Evolutionary Approach (1972)

There is an almost universal tendency, perhaps an inborn tendency, to suspect the good faith of a man who holds opinions that differ from our own opinions. … It obviously endangers the freedom and the objectivity of our discussion if we attack a person instead of attacking an opinion or, more precisely, a theory.

"The Importance of Critical Discussion" in On the Barricades: Religion and Free Inquiry in Conflict (1989) by Robert Basil

Science may be described as the art of systematic over-simplification — the art of discerning what we may with advantage omit.

The Open Universe : An Argument for Indeterminism (1992), p. 44

I think so badly of philosophy that I don't like to talk about it. ... I do not want to say anything bad about my dear colleagues, but the profession of teacher of philosophy is a ridiculous one. We don't need a thousand of trained, and badly trained, philosophers — it is very silly. Actually most of them have nothing to say.

As quoted in "At 90, and Still Dynamic : Revisiting Sir Karl Popper and Attending His Birthday Party" by Eugene Yue-Ching Ho, in Intellectus 23 (Jul-Sep 1992)
Encyclopedia
Sir Karl Raimund Popper, CH
Order of the Companions of Honour
The Order of the Companions of Honour is an order of the Commonwealth realms. It was founded by King George V in June 1917, as a reward for outstanding achievements in the arts, literature, music, science, politics, industry, or religion....

, FRS, FBA (28 July 1902 – 17 September 1994) was an Austrian and British philosopher and a professor at the London School of Economics
London School of Economics
The London School of Economics and Political Science, commonly referred to as the London School of Economics or LSE, is a specialist constituent college of the University of London in London, England....

. He is considered one of the most influential philosophers of science
Philosophy of science
The philosophy of science is concerned with the assumptions, foundations, and implications of science. The field is defined by an interest in one of a set of "traditional" problems or an interest in central or foundational concerns in science...

 of the 20th century, and also wrote extensively on social and political philosophy. Popper is known for repudiating the classical observationalist/inductivist
Inductivism
In the philosophy of science inductivism exists both in a classical naive version, which has been highly influential, and in various more sophisticated versions...

 account of scientific method
Scientific method
Scientific method refers to a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. To be termed scientific, a method of inquiry must be based on gathering observable, empirical and measurable evidence subject to specific...

 by advancing empirical falsification
Falsifiability
Falsifiability is the logical possibility that an assertion can be shown false by an observation or a physical experiment. That something is "falsifiable" does not mean it is false; rather, that if it is false, then this can be shown by observation or experiment. Falsifiability is an important...

 instead; for his opposition to the classical justificationist account of knowledge which he replaced with critical rationalism
Critical rationalism
Critical rationalism is an epistemological philosophy advanced by Karl Popper. Popper wrote about critical rationalism in his works, The Open Society and its Enemies Volume 2, and Conjectures and Refutations.- Criticism, not support :...

, "the first non justificational philosophy of criticism in the history of philosophy", and for his vigorous defense of liberal democracy
Liberal democracy
Liberal democracy is the dominant form of democracy in the 21st century. During the Cold War, liberal democracies were contrasted with the Communist People's Republics or "Popular Democracies", which claimed an alternative conception of democracy...

 and the principles of social criticism
Social criticism
Social criticism analyzes social structures which are seen as flawed and aims at practical solutions by specific measures, radical reform or even revolutionary change....

 that he came to believe made a flourishing "open society
Open society
The open society is a concept originally developed by philosopher Henri Bergson. In open societies, government is responsive and tolerant, and political mechanisms are transparent and flexible....

" possible.

Life


Karl Popper was born in Vienna
Vienna
Vienna is the capital of the Republic of Austria and also one of the nine states of Austria. Vienna is Austria's primary city, with a population of about 1.7 million , and is by far the largest city in Austria, as well as its cultural, economic, and political centre. It is the 10th largest city by...

 (then in Austria-Hungary
Austria-Hungary
Austria–Hungary, also known as the Austro-Hungarian Empire, the Dual Monarchy or the k.u.k. Monarchy, or Dual State, was a monarchic union between the crowns of the Austrian Empire and the Kingdom of Hungary in Central Europe...

) in 1902, to middle-class parents of assimilated Jewish origins, both of whom had converted to Christianity
Christianity
Christianity is a monotheistic religion based on the life and teachings of Jesus of Nazareth as presented by the revelations in the New Testament....

.

Karl's father Dr Simon Siegmund Carl Popper was a lawyer from Prague
Prague
Prague is the capital and largest city of the Czech Republic. Nicknames for Prague have included "the mother of cities" , "city of a hundred spires", or Stověžatá Praha in Czech and "the golden city" or Zlaté město in Czech.Situated on the River Vltava in central Bohemia, Prague has been the...

, and mother Jenny Schiff was of Silesian
Silesian
Silesian or Upper Silesian is a Slavic language spoken in the region of Silesia. The ISO 639-3 language code is szl.- Distribution :...

and Hungarian
Hungarian
Hungarian may refer to:* Hungary, a country in Central Europe* Kingdom of Hungary, state of Hungary, existing from 1000 to 1946* Hungarian people, the ethnic group primarily associated with Hungary...

 descent.

Popper received a Lutheran upbringing and was educated at the University of Vienna
University of Vienna
The University of Vienna is a public university located in Vienna, Austria. It was founded by Duke Rudolph IV in 1365 and is, therefore, the oldest university in the German-speaking world and one of the largest in Central Europe.-History:...

. His father was a doctor of law at the Vienna University and a bibliophile who had 12,000–14,000 volumes in his personal library. Popper inherited from him both the library and the disposition.

In 1919, Popper became attracted by Marxism
Marxism
Marxism is the political philosophy and economic worldview based upon a materialist interpretation of history, a Marxist analysis of capitalism, a theory of social change, and an atheist view of human liberation derived from the work of Karl Marx and Friedrich Engels; three primary aspects of...

 and subsequently joined the Association of Socialist School Students. He also became a member of the Social Democratic Party of Austria
Social Democratic Party of Austria
The Social Democratic Party of Austria is one of the oldest parties in Austria. The SPÖ is one of the major parties in Austria and has particularly strong ties to labor unions and the Austrian Chamber of Labour...

, which was at that time a party that fully adopted the Marxist ideology. He soon became disillusioned by the philosophical restraints imposed by the historical materialism
Historical materialism
Historical materialism is a methodological approach to the study of society, economics, and history, first articulated by Karl Marx...

 of Marx, abandoned the ideology and remained a supporter of social liberalism
Social liberalism
Social liberalism, a reformulation of 19th century liberalism, rests on the view that unrestrained capitalism is a hindrance to true freedom. Instead of the negative freedom of classical liberalism, social liberals offered positive freedom that would allow individuals to prosper with public...

 throughout his life.

In 1928, he earned a doctorate in Philosophy, and then from 1930 to 1936 taught secondary school.
Popper published his first book, Logik der Forschung (The Logic of Scientific Discovery
The Logic of Scientific Discovery
Logik der Forschung is a 1934 book by Karl Popper. It was originally written in German, but reformulated in English by Popper himself some years later, to be published as The Logic of Scientific Discovery in 1959. This forms the rare case of a major work to appear in two languages, both written by...

), in 1934. Here, he criticised psychologism
Psychologism
Psychologism is a generic type of position in philosophy according to which psychology plays a central role in grounding or explaining some other, non-psychological type of fact or law...

, naturalism
Naturalism (philosophy)
Naturalism is divided into two philosophical stances:*Naturalized epistemology which focuses on epistemology: This stance is concerned with knowledge: what are methods for gaining trustworthy knowledge of the natural world? It is an epistemological view that is specifically concerned with practical...

, inductionism
Inductionism
Inductionism is the scientific philosophy where laws are "induced" from sets of data. As an example, one might measure the strength of electrical forces at varying distances from charges and induce the inverse square law of electrostatics....

, and logical positivism
Logical positivism
Logical positivism is a school of philosophy that combines empiricism, the idea that observational evidence is indispensable for knowledge of the world, with a version of rationalism incorporating mathematical and logico-linguistic constructs and deductions in epistemology.See, e.g., : ...

, and put forth his theory of potential falsifiability
Falsifiability
Falsifiability is the logical possibility that an assertion can be shown false by an observation or a physical experiment. That something is "falsifiable" does not mean it is false; rather, that if it is false, then this can be shown by observation or experiment. Falsifiability is an important...

 as the criterion demarcating science from non-science.

In 1937, the rise of Nazism
Nazism
Nazism, known officially in German as National Socialism , is the totalitarian ideology and practices of the Nazi Party or National Socialist German Workers’ Party under Adolf Hitler, and the policies adopted by the dictatorial government of Nazi Germany from 1933 to 1945.Nazism is often considered...

 and the threat of the Anschluss
Anschluss
The ' , also known as the ', was the 1938 de facto annexation of Austria into Greater Germany by the Nazi regime....

 led Popper to emigrate to New Zealand, where he became lecturer in philosophy at Canterbury University College
University of Canterbury
The University of Canterbury , New Zealand's second-oldest university, operates in the suburb of Ilam in the city of Christchurch, New Zealand...

 New Zealand
University of New Zealand
The University of New Zealand was the New Zealand university from 1870 to 1961. It was the sole New Zealand university, having a federal structure embracing several constituent colleges at various locations around New Zealand...

 (at Christchurch). In 1946, he moved to England to
become reader
Reader (academic rank)
The title of Reader in the United Kingdom and for universities in the Commonwealth nations like some in Australia and New Zealand, denotes an appointment for a senior academic with a distinguished international reputation in research or scholarship....

 in logic
Logic
Logic, from the Greek λογική is the art and science of reasoning. More specifically, it is defined by the Penguin Encyclopedia to be "The formal systematic study of the principles of valid inference and correct reasoning". As a discipline, logic dates back to Aristotle, who established its...

 and scientific method
Scientific method
Scientific method refers to a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. To be termed scientific, a method of inquiry must be based on gathering observable, empirical and measurable evidence subject to specific...

 at the London School of Economics
London School of Economics
The London School of Economics and Political Science, commonly referred to as the London School of Economics or LSE, is a specialist constituent college of the University of London in London, England....

. Three years later, he was appointed as professor of logic and scientific method at the University of London in 1949. Popper was president of the Aristotelian Society
Aristotelian Society
The Aristotelian Society for the Systematic Study of Philosophy was founded at a meeting on 19 April 1880, at 17 Bloomsbury Square which resolved "to constitute a society of about twenty and to include ladies; the society to meet fortnightly, on Mondays at 8 o'clock, at the rooms of the Spelling...

 from 1958 to 1959. He was knighted
British honours system
The British honours system is a means of rewarding individuals' personal bravery, achievement, or service to the United Kingdom. The system consists of three types of award: honours, decorations and medals:...

 by Queen Elizabeth II
Elizabeth II of the United Kingdom
Elizabeth II is the queen regnant of sixteen independent states known informally as the Commonwealth realms: the United Kingdom, Canada, Australia, New Zealand, Jamaica, Barbados, the Bahamas, Grenada, Papua New Guinea, the Solomon Islands, Tuvalu, Saint Lucia, Saint Vincent and the Grenadines,...

 in 1965, and was elected a Fellow of the Royal Society
Royal Society
The Royal Society of London for the Improvement of Natural Knowledge, known simply as the Royal Society, or even the Royal, is a learned society for science that was founded in 1660 and is considered by most to be the oldest such society still in existence...

 in 1976. He retired from academic life in 1969, though he remained intellectually active for the rest of his life. He was invested with the Insignia of a Companion of Honour
Order of the Companions of Honour
The Order of the Companions of Honour is an order of the Commonwealth realms. It was founded by King George V in June 1917, as a reward for outstanding achievements in the arts, literature, music, science, politics, industry, or religion....

 in 1982. Popper was a member of the Academy of Humanism and described himself as an agnostic
Agnosticism
Agnosticism is the philosophical view that the truth value of certain claims — particularly metaphysical claims regarding theology, afterlife or the existence of deities, spiritual beings, or even ultimate reality — are unknown or, in some forms of agnosticism, unknowable.It is not a...

, showing respect for the moral teachings of Judaism and Christianity.

Popper won many awards and honours in his field, including the Lippincott Award of the American Political Science Association
American Political Science Association
The American Political Science Association is a professional association of political science students and scholars in the United States. Founded in 1903, it publishes three academic journals...

, the Sonning Prize
Sonning Prize
The Sonning Prize is awarded biennially for outstanding contributions to European culture. A committee headed by the rector of the University of Copenhagen decides among candidates proposed by European universities. The prize amounts to 1 mio DKK . The prize award ceremony is held on April 19 at...

, and fellowships in the Royal Society
Royal Society
The Royal Society of London for the Improvement of Natural Knowledge, known simply as the Royal Society, or even the Royal, is a learned society for science that was founded in 1660 and is considered by most to be the oldest such society still in existence...

, British Academy
British Academy
The British Academy is the United Kingdom's national academy for the humanities and the social sciences. It was established by Royal Charter in 1902, and is a fellowship of more than 800 scholars...

, London School of Economics
London School of Economics
The London School of Economics and Political Science, commonly referred to as the London School of Economics or LSE, is a specialist constituent college of the University of London in London, England....

, King's College London
King's College London
King's College London is a British higher education institution and co-founding constituent college of the University of London. Founded by King George IV and the Duke of Wellington in 1829, its royal charter is predated, in England, only by those of the Universities of Oxford and Cambridge...

, Darwin College
Darwin College, Cambridge
Darwin College is a constituent college of the University of Cambridge. It is a college for advanced study, admitting only postgraduate students....

 Cambridge
University of Cambridge
The University of Cambridge , located in the City of Cambridge, Cambridgeshire, United Kingdom, is the second oldest university in the English-speaking world and the fourth oldest in Europe...

, and Charles University, Prague. Austria awarded him the Grand Decoration of Honour in Gold.

Popper died in Croydon
Croydon
Croydon is a major commercial centre in Greater London and the principal settlement of the London Borough of Croydon. It is south of Charing Cross, and is one of the major metropolitan centres identified in the London Plan...

, UK at the age of 92 on 17 September, 1994. After cremation, his ashes were taken to Vienna
Vienna
Vienna is the capital of the Republic of Austria and also one of the nine states of Austria. Vienna is Austria's primary city, with a population of about 1.7 million , and is by far the largest city in Austria, as well as its cultural, economic, and political centre. It is the 10th largest city by...

 and buried at Lainzer cemetery adjacent to the ORF
ORF
ORF may refer to:* Österreichischer Rundfunk, Austria's national public-service broadcaster* Open reading frame, a portion of the genome* The IATA airport code for Norfolk International Airport in Norfolk, Virginia...

 Centre, where his wife Josefine Anna Henninger, who had died in Austria several years before, had already been buried.

Philosophy of Science


Popper coined the term critical rationalism
Critical rationalism
Critical rationalism is an epistemological philosophy advanced by Karl Popper. Popper wrote about critical rationalism in his works, The Open Society and its Enemies Volume 2, and Conjectures and Refutations.- Criticism, not support :...

to describe his philosophy. The term indicates his rejection of classical empiricism
Empiricism
In philosophy, empiricism is a theory of knowledge which asserts that knowledge arises from sense experience. Empiricism is one of several competing views about how we know "things," part of the branch of philosophy called epistemology, or "the Theory of Knowledge"...

, and of the classical observationalist-inductivist account of science
The classical observationalist-inductivist account of science
The classical observationalist-inductivist account of science is essentially derived from the view of science where new knowledge is the result of past observations and any knowledge derived thereof is purely inductive. Therefore, it is fallible in the sense that it is not capable of understanding...

that had grown out of it. Popper argued strongly against the latter, holding that scientific theories are abstract in nature, and can be tested only indirectly, by reference to their implications. He also held that scientific theory, and human knowledge generally, is irreducibly conjectural or hypothetical, and is generated by the creative imagination in order to solve problems that have arisen in specific historico-cultural settings. Logically, no number of positive outcomes at the level of experimental testing can confirm a scientific theory, but a single counterexample is logically decisive: it shows the theory, from which the implication is derived, to be false. Popper's account of the logical asymmetry between verification
Verification theory
The verification theory is a philosophical theory proposed by the logical positivists of the Vienna Circle. A simplified form of the theory states that a proposition's meaning is determined by the method through which it is empirically verified. In other words, if something cannot be...

 and falsifiability
Falsifiability
Falsifiability is the logical possibility that an assertion can be shown false by an observation or a physical experiment. That something is "falsifiable" does not mean it is false; rather, that if it is false, then this can be shown by observation or experiment. Falsifiability is an important...

 lies at the heart of his philosophy of science. It also inspired him to take falsifiability as his criterion of demarcation
Demarcation problem
The demarcation problem in the philosophy of science is about how and where to draw the lines around science. The boundaries are commonly drawn between science and non-science, between science and pseudoscience, and between science and religion. A form of this problem, known as the generalized...

 between what is and is not genuinely scientific: a theory should be considered scientific if and only if it is falsifiable. This led him to attack the claims of both psychoanalysis
Psychoanalysis
Psychoanalysis is a body of ideas developed by Austrian physician Sigmund Freud and continued by others. It is primarily devoted to the study of human psychological functioning and behavior, although it also can be applied to societies.
...

 and contemporary Marxism
Marxism
Marxism is the political philosophy and economic worldview based upon a materialist interpretation of history, a Marxist analysis of capitalism, a theory of social change, and an atheist view of human liberation derived from the work of Karl Marx and Friedrich Engels; three primary aspects of...

 to scientific status, on the basis that the theories enshrined by them are not falsifiable. Popper also wrote extensively against the famous Copenhagen interpretation
Copenhagen interpretation
The Copenhagen interpretation is an interpretation of quantum mechanics. A key feature of quantum mechanics is that the state of every particle is described by a wavefunction, which is a mathematical representation used to calculate the probability for it to be found in a location or a state of...

 of quantum mechanics
Quantum mechanics
Quantum mechanics is a set of principles describing the physical reality at the atomic level of matter and the subatomic . These descriptions include the simultaneous wave-like and particle-like behavior of both matter and radiation...

. He strongly disagreed with Niels Bohr
Niels Bohr
Niels Henrik David Bohr was a Danish physicist who made fundamental contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in Physics in 1922. Bohr mentored and collaborated with many of the top physicists of the century at his institute in...

's instrumentalism
Instrumentalism
In the philosophy of science, instrumentalism is the view that a concept or theory should be evaluated by how effectively it explains and predicts phenomena, as opposed to how accurately it describes objective reality....

 and supported Albert Einstein
Albert Einstein
Albert Einstein was a theoretical physicist. His many contributions to physics include the special and general theories of relativity, the founding of relativistic cosmology, the first post-Newtonian expansion, explaining the perihelion advance of Mercury, prediction of the deflection of...

's realist
Scientific realism
Scientific realism is, at the most general level, the view that the world described by science is the real world, as it is, independent of what we might take it to be. Within philosophy of science, it is often framed as an answer to the question "what does the success of science involve?"...

 approach to scientific theories about the universe. Popper's falsifiability resembles Charles Peirce's fallibilism
Fallibilism
Fallibilism is the philosophical doctrine that all claims of knowledge could, in principle, be mistaken. Some fallibilists go further, arguing that absolute certainty about knowledge is impossible. As a formal doctrine, it is most strongly associated with Charles Sanders Peirce, John Dewey, and...

. In Of Clocks and Clouds (1966), Popper remarked that he wished he had known of Peirce's work earlier.

In All Life is Problem Solving, Popper sought to explain the apparent progress of scientific knowledge—how it is that our understanding of the universe seems to improve over time. This problem arises from his position that the truth content of our theories, even the best of them, cannot be verified by scientific testing, but can only be falsified. If so, then how is it that the growth of science appears to result in a growth in knowledge? In Popper's view, the advance of scientific knowledge is an evolutionary process characterised by his formula:

.


In response to a given problem situation , a number of competing conjectures, or tentative theories , are systematically subjected to the most rigorous attempts at falsification possible. This process, error elimination , performs a similar function for science that natural selection
Natural selection
Natural selection is the process by which heritable traits that make it more likely for an organism to survive and successfully reproduce become more common in a population over successive generations...

 performs for biological evolution. Theories that better survive the process of refutation are not more true, but rather, more "fit"—in other words, more applicable to the problem situation at hand . Consequently, just as a species' "biological fit" does not predict continued survival, neither does rigorous testing protect a scientific theory from refutation in the future. Yet, as it appears that the engine of biological evolution has produced, over time, adaptive traits equipped to deal with more and more complex problems of survival, likewise, the evolution of theories through the scientific method may, in Popper's view, reflect a certain type of progress: toward more and more interesting problems . For Popper, it is in the interplay between the tentative theories (conjectures) and error elimination (refutation) that scientific knowledge advances toward greater and greater problems; in a process very much akin to the interplay between genetic variation and natural selection.

Where does "truth" fit into all this? As early as 1934 Popper wrote of the search for truth as "one of the strongest motives for scientific discovery." Still, he describes in Objective Knowledge (1972) early concerns about the much-criticised notion of truth as correspondence
Correspondence theory of truth
The correspondence theory of truth states that the truth or falsity of a statement is determined only by how it relates to the world, and whether it accurately describes that world...

. Then came the semantic theory of truth
Semantic theory of truth
The semantic theory of truth holds that any assertion that a sentence is true can be made only as a formal requirement regarding the language in which the proposition itself is expressed.-Origin:...

 formulated by the logician Alfred Tarski
Alfred Tarski
Alfred Tarski was a Polish logician and mathematician...

 and published in 1933. Popper writes of learning in 1935 of the consequences of Tarski's theory, to his intense joy. The theory met critical objections to truth
Truth
Truth can have a variety of meanings, from the state of being the case, being in accord with a particular fact or reality, being in accord with the body of real things, events, actuality, or fidelity to an original or to a standard. In archaic usage it could be fidelity, constancy or sincerity in...

 as correspondence and thereby rehabilitated it. The theory also seemed, in Popper's eyes, to support metaphysical realism and the regulative idea of a search for truth.

According to this theory, the conditions for the truth of a sentence as well as the sentences themselves are part of a metalanguage
Metalanguage
In logic and linguistics, a metalanguage is a language used to make statements about statements in another language which is called the object language. It can refer to any terminology or language used to discuss language itself—a written grammar, for example, or a discussion about language use...

. So, for example, the sentence "Snow is white" is true if and only if snow is white. Although many philosophers have interpreted, and continue to interpret, Tarski's theory as a deflationary theory
Deflationary theory of truth
The deflationary theory of truth is a family of theories which all have in common the claim that assertions that predicate truth of a statement do not attribute a property called truth to such a statement.-Redundancy theory:...

, Popper refers to it as a theory in which "is true" is replaced with "corresponds to the facts." He bases this interpretation on the fact that examples such as the one described above refer to two things: assertions and the facts to which they refer. He identifies Tarski's formulation of the truth conditions of sentences as the introduction of a "metalinguistic predicate" and distinguishes the following cases:
  1. "John called" is true.
  2. "It is true that John called."


The first case belongs to the metalanguage whereas the second is more likely to belong to the object language. Hence, "it is true that" possesses the logical status of a redundancy. "Is true", on the other hand, is a predicate necessary for making general observations such as "John was telling the truth about Phillip."

Upon this basis, along with that of the logical content of assertions (where logical content is inversely proportional to probability), Popper went on to develop his important notion of verisimilitude
Verisimilitude
Verisimilitude—or truthlikeness—in the philosophy of science is trying to articulate how a false theory could be closer to the truth than another false theory. This usage was mostly popularized by Karl Popper. He assumed that science was interested in the informative content of a theory because...

 or "truthlikeness".

The intuitive idea behind verisimilitude is that the assertions or hypotheses of scientific theories can be objectively measured with respect to the amount of truth and falsity that they imply. And, in this way, one theory can be evaluated as more or less true than another on a quantitative basis which, Popper emphasizes forcefully, has nothing to do with "subjective probabilities" or other merely "epistemic" considerations.

The simplest mathematical formulation that Popper gives of this concept can be found in the tenth chapter of Conjectures and Refutations
Conjectures and Refutations
Conjectures and Refutations: The Growth of Scientific Knowledge is a book written by philosopher Karl Popper.Published in 1963 by Routledge, this book is a collection of his lectures and papers that summarised his thoughts on the philosophy of science...

.
. Here he defines it as:



where is the verisimilitude of a, is a measure of the content of truth of a, and is a measure of the content of the falsity of a.

Knowledge, for Popper, was objective, both in the sense that it is objectively true (or truthlike), and also in the sense that knowledge has an ontological status (i.e., knowledge as object) independent of the knowing subject (Objective Knowledge: An Evolutionary Approach, 1972). He proposed three worlds (see Popperian cosmology
Popperian cosmology
Popperian cosmology is Karl Popper's philosophical theory of reality that includes three interacting worlds, called World 1, World 2 and World 3...

): World One, being the physical world, or physical states; World Two, being the world of mind, or mental states, ideas, and perceptions; and World Three, being the body of human knowledge expressed in its manifold forms, or the products of the second world made manifest in the materials of the first world (i.e.–books, papers, paintings, symphonies, and all the products of the human mind). World Three, he argued, was the product of individual human beings in exactly the same sense that an animal path is the product of individual animals, and that, as such, has an existence and evolution independent of any individual knowing subjects. The influence of World Three, in his view, on the individual human mind (World Two) is at least as strong as the influence of World One. In other words, the knowledge held by a given individual mind owes at least as much to the total accumulated wealth of human knowledge, made manifest, as to the world of direct experience. As such, the growth of human knowledge could be said to be a function of the independent evolution of World Three. Many contemporary philosophers have not embraced Popper's Three World conjecture, due mostly, it seems, to its resemblance to Cartesian dualism.

Political philosophy



In The Open Society and Its Enemies
The Open Society and Its Enemies
The Open Society and Its Enemies is an influential two-volume work by Karl Popper written during World War II. Failing to find a publisher in the United States, it was first printed in London by Routledge in 1945...

and The Poverty of Historicism
The Poverty of Historicism
The Poverty of Historicism is a book by twentieth century philosopher Karl Popper which seeks to persuade the reader of both the danger and the bankruptcy of the idea of historicism.-Publication:...

, Popper developed a critique of historicism
Historicism
Historicism refers to philosophical theories that include one or both of two claims:# that there is an organic succession of developments, a notion also known as historism , and/or;...

 and a defence of the 'Open Society'. Historicism is the theory that history develops inexorably and necessarily according to knowable general laws towards a determinate end. Popper argued that this view is the principal theoretical presupposition underpinning most forms of authoritarianism
Authoritarianism
Authoritarianism describes a form of government characterized by an emphasis on the authority of state in a republic or union. It is a political system controlled by typically non-elected rulers who usually permit some degree of individual freedom....

 and totalitarianism
Totalitarianism
Totalitarianism is a political system where the state, usually under the control of a single party or faction, recognizes no limits to its authority and strives to regulate every aspect of public and private life wherever feasible...

. He argued that historicism is founded upon mistaken assumptions regarding the nature of scientific law and prediction. Since the growth of human knowledge is a causal factor in the evolution of human history, and since "no society can predict, scientifically, its own future states of knowledge", it follows, he argued, that there can be no predictive science of human history. For Popper, metaphysical and historical indeterminism go hand in hand.

In a 1992 lecture, Popper explained the connection between his political philosophy and his philosophy of science. As he stated, he was in his early years impressed by communism and also active in the Austrian Communist party. What had a profound effect on him was an event that happened in 1918: during a riot, caused by the Communists, the police shot several people, including some of Popper's friends. When Popper later told the leaders of the Communist party about this, they responded by stating that this loss of life was necessary in working towards the inevitable workers' revolution. This statement did not convince Popper and he started to think about what kind of reasoning would justify such a statement. He later concluded that there could not be any justification for it, and this was the start of his later criticism of historicism.

Problem of Induction


Among his contributions to philosophy is his attempt to answer the philosophical problem of induction
Problem of induction
The problem of induction is the philosophical question of whether inductive reasoning leads to knowledge. That is, what is the justification for either:...

 as emphasized strongly by David Hume
David Hume
David Hume was a Scottish philosopher, economist, historian and a key figure in the history of Western philosophy and the Scottish Enlightenment...

. The problem, in basic terms, can be understood by example: given that the sun has risen every day for as long as anyone can remember, what is the rational proof that it will rise tomorrow? How can one rationally prove that past events will continue to repeat in the future, just because they have repeated in the past?

Popper claims to have found a solution to the problem of induction. His reply is characteristic, and ties in with his criterion of falsifiability. He states that while there is no way to prove that the sun will rise, it is possible to formulate the theory that every day the sun will rise—if it does not rise on some particular day, the theory will be falsified and will have to be replaced by a different one. Until that day, there is no need to reject the assumption that the theory is true. Neither is it rational according to Popper to instead make the more complex assumption that the sun has risen until a given day, but will stop so doing the next day, or similar statements with additional conditions.

Such a theory would be true with higher probability, because it cannot be attacked so easily: To falsify the first one, it is sufficient to find that sun has stopped rising; to falsify the second one, one additionally needs the assumption that the given day has not yet been reached. Popper held that it is the least likely, or most easily falsifiable, or simplest theory (attributes which he all identified as the same thing) that explains known facts that one should rationally prefer. His opposition to positivism, which held that it is the theory most likely to be true that one should prefer, here becomes very apparent. It is impossible, Popper argues, to ensure a theory to be true (but not fatal, since even false theories may have true consequence); it is more important that they can be eliminated and corrected as easy as possible if false.

Popper and Hume
Hume
Hume is a surname that originated in the South East of Scotland, of which the senior representatives are the Earls of Home...

 agreed that there is often a psychological belief that the sun will rise tomorrow, but both denied that there is logical justification for the supposition that it will, simply because it always has in the past. Popper writes:
"I approached the problem of induction through Hume. Hume, I felt, was perfectly right in pointing out that induction cannot be logically justified." (Conjectures and Refutations, p. 55)


To Popper, who was an anti-justificationist, traditional philosophy is misled by the false principle of sufficient reason
Principle of sufficient reason
The principle of sufficient reason states that anything that happens does so for a definite reason. In virtue of which no fact can be real or no statement true unless it has sufficient reason why it should not be otherwise...

. He thinks that no assumption can ever be or needs ever to be justified, so a lack of justification is not a justification for doubt. Instead, theories should be tested and scrutinized. It is not the goal to bless theories with claims of certainty or justification, but to eliminate errors in them.

Free Will


Popper and John Eccles speculated on the problem of free will
Free will
Free will raises the question whether, and in what sense, rational agents exercise control over their actions, decisions, choices. Addressing this question requires understanding the relationship between freedom and cause, and determining whether the laws of nature are causally deterministic...

 for many years, generally agreeing on an interactionist dualist theory of mind as a separate physical substance. When he gave the first Arthur Holly Compton Memorial Lecture in 1955, Popper revisited the idea of quantum indeterminacy
Quantum indeterminacy
Quantum indeterminacy is the apparent necessary incompleteness in the description of a physical system, that has become one of the characteristics of the standard description of quantum physics...

 as a source of human freedom. Eccles had suggested that "critically poised neurons" might be influenced by the mind to assist in a decision.

Popper criticized Compton's idea of amplified quantum events affecting the decision. He wrote

"The idea that the only alternative to determinism is just sheer chance was taken over by Schlick
Moritz Schlick
Moritz Schlick was a German philosopher and the founding father of logical positivism and the Vienna Circle.-Early Life and Works:...

, together with many of his views on the subject, from Hume
David Hume
David Hume was a Scottish philosopher, economist, historian and a key figure in the history of Western philosophy and the Scottish Enlightenment...

, who asserted that 'the removal' of what he called 'physical necessity' must always result in

'the same thing with chance. As objects must either be conjoin'd or not, . . . 'tis impossible to admit of any medium betwixt chance and an absolute necessity'.



"I shall later argue against this important doctrine according to which the alternative to determinism is sheer chance. Yet I must admit that the doctrine seems to hold good for the quantum-theoretical models which have been designed to explain, or at least to illustrate, the possibility of human freedom. This seems to be the reason why these models are so very unsatisfactory.


"Hume's and Schlick's ontological thesis that there cannot exist anything intermediate between chance and determinism seems to me not only highly dogmatic (not to say doctrinaire) but clearly absurd; and it is understandable only on the assumption that they believed in a complete determinism in which chance has no status except as a symptom of our ignorance."


Popper called not for something between chance and necessity but for a combination of randomness and control to explain freedom, though not yet explicitly in two stages with random chance before the controlled decision.

"freedom is not just chance but, rather, the result of a subtle interplay between something almost random or haphazard, and something like a restrictive or selective control."


Then in his 1977 book with John Eccles, The Self and its Brain, Popper finally formulates the two-stage model in a temporal sequence. And he compares free will to Darwinian evolution and natural selection,

"New ideas have a striking similarity to genetic mutations. Now, let us look for a moment at genetic mutations. Mutations are, it seems, brought about by quantum theoretical indeterminacy (including radiation effects). Accordingly, they are also probabilistic and not in themselves originally selected or adequate, but on them there subsequently operates natural selection which eliminates inappropriate mutations. Now we could conceive of a similar process with respect to new ideas and to free-will decisions, and similar things.


"That is to say, a range of possibilities is brought about by a probabilistic and quantum mechanically characterized set of proposals, as it were - of possibilities brought forward by the brain. On these there then operates a kind of selective procedure which eliminates those proposals and those possibilities which are not acceptable to the mind."



Other thinkers who have formulated a two-stage model for free will include William James
William James
William James was a pioneering American psychologist and philosopher trained as a medical doctor. He wrote influential books on the young science of psychology, educational psychology, psychology of religious experience and mysticism, and the philosophy of pragmatism...

, Henri Poincaré
Henri Poincaré
Jules Henri Poincaré was a French mathematician and theoretical physicist, and a philosopher of science...

, Compton
Compton
-Canada:* Compton, Quebec* Compton County, Quebec* Compton , a former Quebec provincial electoral district now part of Mégantic-Compton* Compton , a former Quebec federal electoral district-England:...

, Henry Margenau
Henry Margenau
Henry Margenau was a German-U.S. physicist, and philosopher of science.-Early life:Born Bielefeld, Germany, Margenau obtained his bachelor's degree from Midland Lutheran College, Nebraska before his M.Sc. from the University of Nebraska in 1926, and Ph.D...

, and Daniel Dennett
Daniel Dennett
Daniel Clement Dennett is a prominent American philosopher whose research centers on philosophy of mind, philosophy of science and philosophy of biology, particularly as those fields relate to evolutionary biology and cognitive science. He is currently the co-director of the Center for Cognitive...

.

Issue of Darwinism


Karl Popper famously stated "Darwinism
Darwinism
Darwinism is a term used for various movements or concepts related to ideas of transmutation of species or evolution, including ideas with no connection to the work of Charles Darwin. The meaning of Darwinism has changed over time, and varies depending on who is using the term...

 is not a testable scientific theory, but a metaphysical
Metaphysics
Metaphysics investigates principles of reality transcending those of any particular science. Cosmology and ontology are traditional branches of metaphysics. It is concerned with explaining the fundamental nature of being and the world...

 research program." In the same paper, he continued He also noted that theism presented as explaining adaptation "was worse than an open admission of failure, for it created the impression that an ultimate explanation had been reached."
He later said

He explained that the difficulty of testing had led some people to describe natural selection as a tautology
Tautology
Tautology may refer to:*Tautology , repetition of meaning, using dissimilar words to say the same thing twice, especially where the additional words fail to provide additional clarity and meaning....

, and that he too had in the past described the theory as 'almost tautological', and had tried to explain how the theory could be untestable (as is a tautology) and yet of great scientific interest. His

Influence


By all accounts, Popper has played a vital role in establishing the philosophy of science
Philosophy of science
The philosophy of science is concerned with the assumptions, foundations, and implications of science. The field is defined by an interest in one of a set of "traditional" problems or an interest in central or foundational concerns in science...

 as a vigorous, autonomous discipline within analytic philosophy
Analytic philosophy
Analytic philosophy is a generic term for a style of philosophy that came to dominate English-speaking countries in the 20th century...

, through his own prolific and influential works, and also through his influence on his own contemporaries and students. Popper founded in 1946 the Department of Philosophy, Logic and Scientific Method at the London School of Economics
London School of Economics
The London School of Economics and Political Science, commonly referred to as the London School of Economics or LSE, is a specialist constituent college of the University of London in London, England....

 and there lectured and influenced both Imre Lakatos
Imre Lakatos
Imre Lakatos was a philosopher of mathematics and science, known for his thesis of the fallibility of mathematics and its 'methodology of proofs and refutations', and also for introducing the concept of the 'research programme' in his methodology of scientific research programmes.-Life:Lakatos was...

 and Paul Feyerabend
Paul Feyerabend
Paul Karl Feyerabend was an Austrian-born philosopher of science best known for his work as a professor of philosophy at the University of California, Berkeley, where he worked for three decades...

, two of the foremost philosophers of science in the next generation of philosophy of science. (Lakatos significantly modified Popper's position, and Feyerabend repudiated it entirely, but the work of both is deeply influenced by Popper and engaged with many of the problems that Popper set.)

While there is some dispute as to the matter of influence, Popper had a long-standing and close friendship with economist Friedrich Hayek
Friedrich Hayek
Friedrich August von Hayek CH , was an Austrian and British economist and philosopher known for his defense of classical liberalism and free-market capitalism against socialist and collectivist thought. He is considered by some to be one of the most important economists and political philosophers...

, who was also brought to the London School of Economics
London School of Economics
The London School of Economics and Political Science, commonly referred to as the London School of Economics or LSE, is a specialist constituent college of the University of London in London, England....

 from Vienna. Each found support and similarities in each other's work, citing each other often, though not without qualification. In a letter to Hayek in 1944, Popper stated, "I think I have learnt more from you than from any other living thinker, except perhaps Alfred Tarski
Alfred Tarski
Alfred Tarski was a Polish logician and mathematician...

." (See Hacohen, 2000). Popper dedicated his Conjectures and Refutations
Conjectures and Refutations
Conjectures and Refutations: The Growth of Scientific Knowledge is a book written by philosopher Karl Popper.Published in 1963 by Routledge, this book is a collection of his lectures and papers that summarised his thoughts on the philosophy of science...

to Hayek. For his part, Hayek dedicated a collection of papers, Studies in Philosophy, Politics, and Economics, to Popper, and in 1982 said, "...ever since his Logik der Forschung first came out in 1934, I have been a complete adherent to his general theory of methodology." (See Weimer and Palermo, 1982).

Popper also had long and mutually influential friendships with art historian Ernst Gombrich
Ernst Gombrich
Sir Ernst Hans Josef Gombrich, OM, CBE was an Austrian-born art historian who spent most of his working life in the United Kingdom...

, biologist Peter Medawar
Peter Medawar
Sir Peter Brian Medawar OM CBE FRS was a British zoologist. Medawar's work on graft rejection and the discovery of acquired immune tolerance was fundamental to the practice of tissue and organ transplants. He was awarded the 1960 Nobel Prize in Physiology or Medicine with Sir Frank Macfarlane Burnet...

, and neuro-scientist John Carew Eccles
John Carew Eccles
Sir John Carew Eccles, AC FRS FRACP FRSNZ FAAS was an Australian neurophysiologist who won the 1963 Nobel Prize in Physiology or Medicine for his work on the synapse. He shared the prize together with Andrew Fielding Huxley and Alan Lloyd Hodgkin.- Biography :Eccles was born in Melbourne, Australia...

.

Popper's influence, both through his work in philosophy of science and through his political philosophy, has also extended beyond the academy. Among Popper's students and advocates at the London School of Economics
London School of Economics
The London School of Economics and Political Science, commonly referred to as the London School of Economics or LSE, is a specialist constituent college of the University of London in London, England....

 is the multibillionaire investor George Soros
George Soros
George Soros is an American currency speculator, stock investor, businessman, philanthropist, and political activist....

, who says his investment strategies are modelled on Popper's understanding of the advancement of knowledge through the distinctly Hegelian idea of falsification
Falsifiability
Falsifiability is the logical possibility that an assertion can be shown false by an observation or a physical experiment. That something is "falsifiable" does not mean it is false; rather, that if it is false, then this can be shown by observation or experiment. Falsifiability is an important...

. Among Soros's philanthropic
Philanthropy
Philanthropy is the effort or inclination to increase the well-being of humankind, as by charitable aid or donations.- Definition :It is generally agreed that the word was coined 2500 years ago in ancient Greece, by the playwright Aeschylus, or whom ever else wrote Prometheus Bound...

 foundations is the Open Society Institute
Open Society Institute
The Open Society Institute , a private operating and grantmaking foundation, aims to shape public policy to promote democratic governance, human rights, and economic, legal, and social reform. On a local level, OSI implements a range of initiatives to support the rule of law, education, public...

, a think-tank named in honour of Popper's The Open Society and Its Enemies
The Open Society and Its Enemies
The Open Society and Its Enemies is an influential two-volume work by Karl Popper written during World War II. Failing to find a publisher in the United States, it was first printed in London by Routledge in 1945...

, which Soros founded to advance the Popperian defense of the open society
Open society
The open society is a concept originally developed by philosopher Henri Bergson. In open societies, government is responsive and tolerant, and political mechanisms are transparent and flexible....

 against authoritarianism
Authoritarianism
Authoritarianism describes a form of government characterized by an emphasis on the authority of state in a republic or union. It is a political system controlled by typically non-elected rulers who usually permit some degree of individual freedom....

 and totalitarianism
Totalitarianism
Totalitarianism is a political system where the state, usually under the control of a single party or faction, recognizes no limits to its authority and strives to regulate every aspect of public and private life wherever feasible...

.

Popperian philosophy also inspired the creation of Taking Children Seriously
Taking Children Seriously
Taking Children Seriously is a parenting movement and educational philosophy whose central idea is that is possible and desirable to raise and educate children without either doing anything to them against their will, or making them do anything against their will.It was founded in 1994 as an email...

, a libertarian movement which noticed that Popper's general theory of knowledge creation does not differentiate between adults and children.

Criticism of his philosophy of science


Most criticisms of Popper's philosophy are of the falsification, or error elimination, element in his account of problem solving. In interpreting these, it is important to bear in mind the aims of his idea. It is intended as an ideal, practical method of effective human problem solving; as such, the current conclusions of science are stronger than pseudo-sciences or non-sciences, insofar as they have survived this particularly vigorous selection method. He does not argue that any such conclusions are therefore true, or that this describes the actual methods of any particular scientist.

Rather, it is a recommended ideal method that, if enacted by a system or community, will over time lead to slow but steady progress of a sort (relative to how well the system or community enacts the method). It has been suggested that Popper's ideas are often mistaken for a hard logical account of truth because of the historical co-incidence of their appearing at the same time as logical positivism
Logical positivism
Logical positivism is a school of philosophy that combines empiricism, the idea that observational evidence is indispensable for knowledge of the world, with a version of rationalism incorporating mathematical and logico-linguistic constructs and deductions in epistemology.See, e.g., : ...

, the followers of which mistook his aims for their own (Bryan Magee 1973: Popper (Modern Masters series)).

The Quine-Duhem thesis
Confirmation holism
Confirmation holism, also called epistemological holism is the claim that a single scientific theory cannot be tested in isolation; a test of one theory always depends on other theories and hypotheses....

 argues that it's impossible to test a single hypothesis on its own, since each one comes as part of an environment of theories. Thus we can only say that the whole package of relevant theories has been collectively falsified, but cannot conclusively say which element of the package must be replaced. An example of this is given by the discovery of the planet Neptune
Neptune
Neptune is the eighth planet from the Sun in our Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third-largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 Earth masses and...

: when the motion of Uranus
Uranus
Uranus is the seventh planet from the Sun, and the third-largest and fourth most massive planet in the Solar System. It is named after the ancient Greek deity of the sky Uranus the father of Kronos and grandfather of Zeus...

 was found not to match the predictions of Newton's laws, the theory "There are seven planets in the solar system" was rejected, and not Newton's laws themselves. Popper discussed this critique of naïve falsificationism in Chapters 3 & 4 of The Logic of Scientific Discovery
The Logic of Scientific Discovery
Logik der Forschung is a 1934 book by Karl Popper. It was originally written in German, but reformulated in English by Popper himself some years later, to be published as The Logic of Scientific Discovery in 1959. This forms the rare case of a major work to appear in two languages, both written by...

. For Popper, theories are accepted or rejected via a sort of selection process. Theories that say more about the way things appear are to be preferred over those that do not; the more generally applicable a theory is, the greater its value. Thus Newton’s laws, with their wide general application, are to be preferred over the much more specific “the solar system has seven planets”.

Thomas Kuhn’s influential book The Structure of Scientific Revolutions
The Structure of Scientific Revolutions
The Structure of Scientific Revolutions , by Thomas Kuhn, is an analysis of the history of science. Its publication was a landmark event in the sociology of knowledge, and popularized the terms paradigm and paradigm shift.-History:...

argued that scientists work in a series of paradigm
Paradigm
The word paradigm has been used in linguistics and science to describe distinct concepts....

s, and found little evidence of scientists actually following a falsificationist methodology. Popper's student Imre Lakatos
Imre Lakatos
Imre Lakatos was a philosopher of mathematics and science, known for his thesis of the fallibility of mathematics and its 'methodology of proofs and refutations', and also for introducing the concept of the 'research programme' in his methodology of scientific research programmes.-Life:Lakatos was...

 attempted to reconcile Kuhn’s work with falsificationism by arguing that science progresses by the falsification of research programs rather than the more specific universal statements
Universal quantification
In predicate logic, universal quantification formalizes the notion that something is true for everything, or every relevant thing....

 of naïve falsificationism. Another of Popper’s students Paul Feyerabend
Paul Feyerabend
Paul Karl Feyerabend was an Austrian-born philosopher of science best known for his work as a professor of philosophy at the University of California, Berkeley, where he worked for three decades...

 ultimately rejected any prescriptive methodology, and argued that the only universal method characterizing scientific progress was anything goes.

Popper seems to have anticipated Kuhn's observations. In his collection Conjectures and Refutations
Conjectures and Refutations
Conjectures and Refutations: The Growth of Scientific Knowledge is a book written by philosopher Karl Popper.Published in 1963 by Routledge, this book is a collection of his lectures and papers that summarised his thoughts on the philosophy of science...

: The Growth of Scientific Knowledge
(Harper & Row, 1963), Popper writes, "Science must begin with myths, and with the criticism of myths; neither with the collection of observations, nor with the invention of experiments, but with the critical discussion of myths, and of magical techniques and practices. The scientific tradition is distinguished from the pre-scientific tradition in having two layers. Like the latter, it passes on its theories; but it also passes on a critical attitude towards them. The theories are passed on, not as dogmas, but rather with the challenge to discuss them and improve upon them."

Another objection is that it is not always possible to demonstrate falsehood definitively, especially if one is using statistical
Statistical significance
In statistics, a result is called statistically significant if it is unlikely to have occurred by chance. The phrase test of significance was coined by Ronald Fisher....

 criteria to evaluate a null hypothesis
Null hypothesis
In statistical hypothesis testing, the null hypothesis formally describes some aspect of the statistical "behaviour" of a set of data. This description is assumed to be valid unless the actual behaviour of the data contradicts this assumption. Thus, the null hypothesis is contrasted against...

. More generally it is not always clear, if evidence contradicts a hypothesis, that this is a sign of flaws in the hypothesis rather than of flaws in the evidence. However, this is a misunderstanding of what Popper's philosophy of science sets out to do. Rather than offering a set of instructions that merely need to be followed diligently to achieve science, Popper makes it clear in The Logic of Scientific Discovery
The Logic of Scientific Discovery
Logik der Forschung is a 1934 book by Karl Popper. It was originally written in German, but reformulated in English by Popper himself some years later, to be published as The Logic of Scientific Discovery in 1959. This forms the rare case of a major work to appear in two languages, both written by...

that his belief is that the resolution of conflicts between hypotheses and observations can only be a matter of the collective judgment of scientists, in each individual case.

Popper's falsificationism can be questioned logically, by asking about statements such as "There are black hole
Black hole
In general relativity, a black hole is a region of space in which the gravitational field is so powerful that nothing, not even light, can escape. The black hole has a one-way surface, called an event horizon, into which objects can fall, but out of which nothing can come...

s", which cannot be falsified by any possible observation yet seem to be scientifically legitimate claims. Similarly, it is not clear how Popper would deal with a statement like "for every metal, there is a temperature at which it will melt", which can neither be confirmed nor falsified by any possible observation, yet which seems to be a valid scientific hypothesis. These examples were pointed out by Carl Gustav Hempel
Carl Gustav Hempel
Carl Gustav "Peter" Hempel was a philosopher of science and a major figure in 20th-century logical empiricism...

. Hempel came to acknowledge that Logical Positivism's verificationism was untenable, but argued that falsificationism was equally untenable on logical grounds alone. The simplest response to this is that, because Popper describes how theories attain, maintain and lose scientific status, individual consequences of currently accepted scientific theories are scientific in the sense of being part of tentative scientific knowledge, and both of Hempel's examples fall under this category. For instance, atomic theory
Atomic theory
In chemistry and physics, atomic theory is a theory of the nature of matter, which states that matter is composed of discrete units called atoms, as opposed to the obsolete notion that matter could be divided into any arbitrarily small quantity...

 implies that all metals melt at some temperature.

An early German-speaking adversary of so-called critical rationalism, Karl-Otto Apel
Karl-Otto Apel
Karl-Otto Apel is a German philosopher and Professor Emeritus at the University of Frankfurt am Main. Apel worked in ethics, the philosophy of language and human sciences. He wrote extensively in these fields, and published widely in German and foreign languages, although much of his work is not...

 attempted a comprehensive refutation of Popper's philosophy. In Transformation der Philosophie (1973), Apel charged Popper with being guilty of, amongst other things, a pragmatic contradiction.

Other criticisms


Other critics seek to vindicate the claims of historicism
Historicism
Historicism refers to philosophical theories that include one or both of two claims:# that there is an organic succession of developments, a notion also known as historism , and/or;...

 or holism
Holism
Holism is the idea that all the properties of a given system cannot be determined or explained by its component parts alone...

 to intellectual respectability, or psychoanalysis
Psychoanalysis
Psychoanalysis is a body of ideas developed by Austrian physician Sigmund Freud and continued by others. It is primarily devoted to the study of human psychological functioning and behavior, although it also can be applied to societies.
...

 or Marxism
Marxism
Marxism is the political philosophy and economic worldview based upon a materialist interpretation of history, a Marxist analysis of capitalism, a theory of social change, and an atheist view of human liberation derived from the work of Karl Marx and Friedrich Engels; three primary aspects of...

 to scientific status. It has been argued that Popper's student Imre Lakatos
Imre Lakatos
Imre Lakatos was a philosopher of mathematics and science, known for his thesis of the fallibility of mathematics and its 'methodology of proofs and refutations', and also for introducing the concept of the 'research programme' in his methodology of scientific research programmes.-Life:Lakatos was...

, for example, transformed Popper's philosophy using historicist and updated Hegelian historiographic ideas.

Ludwig Wittgenstein
Ludwig Wittgenstein
Ludwig Josef Johann Wittgenstein was an Austrian-British philosopher who worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language....

 was accused of brandishing a poker at his fellow philosopher Karl Popper at a meeting of the Cambridge Moral Science Club as they argued about whether issues in philosophy were real or just linguistic puzzles. In actuality, Wittgenstein was merely handling a poker but Popper used the situation to make a joke at Wittgenstein's expense.

Charles Taylor
Charles Taylor (philosopher)
Charles Margrave Taylor, CC, GOQ, FRSC is a Canadian philosopher from Montreal, Quebec, Canada, who has made contributions to political philosophy, philosophy of social science, and the history of philosophy. He is often classified as a communitarian, but is uncomfortable with the label. Taylor is...

 accuses Popper of exploiting his worldwide fame as an epistemologist to diminish the importance of philosophers of the 20th century continental tradition
Continental philosophy
Continental philosophy, in contemporary usage, refers to a set of traditions of 19th and 20th century philosophy from mainland Europe. This sense of the term originated among English-speaking philosophers in the second half of the 20th century, who found it useful for referring to a range of...

. According to Taylor, Popper's criticisms are completely baseless, but they are received with an attention and respect that Popper's "intrinsic worth hardly merits". William W. Bartley defended Popper against such allegations: "Sir Karl Popper is not really a participant in the contemporary professional philosophical dialogue; quite the contrary, he has ruined that dialogue. If he is on the right track, then the majority of professional philosophers the world over has wasted or is wasting their intellectual careers. 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."

In 2004, philosopher and psychologist
Psychologist
A psychologist is someone who studies the human mind and behavior. Research psychologists study human perception, cognition, attention, emotion, motivation, personality, behavior and interpersonal relationships...

 Michel ter Hark (Groningen
Groningen (city)
||-| |-| |-| |-| |-| |-| |-| |-| |}Groningen is the capital city of the province of Groningen in the Netherlands. With a population of 185,000, it is by far the largest city in the north of the Netherlands....

, The Netherlands) published a book, called Popper, Otto Selz and the rise of evolutionary epistemology, ISBN 0521830745, in which he claimed that Popper took some of his ideas from his tutor, the German-Jewish psychologist Otto Selz
Otto Selz
Otto Selz, was a German psychologist from Munich, Bavaria, who formulated the first nonassociationist theory of thinking, in 1913. Selz used the method of introspection, but unlike his predecessors, his theory developed without the use of images and associations...

. Selz himself never published his ideas, partly because of the rise of Nazism
Nazism
Nazism, known officially in German as National Socialism , is the totalitarian ideology and practices of the Nazi Party or National Socialist German Workers’ Party under Adolf Hitler, and the policies adopted by the dictatorial government of Nazi Germany from 1933 to 1945.Nazism is often considered...

 which forced him to quit his work in 1933, and the prohibition of referring to Selz' work. Popper, the historian of ideas and his scholarship, is criticized in some academic quarters, for his rejection of Plato, Hegel and Marx.

According to Karl Popper, a theory is scientific only in so far as it is falsifiable, and should be given up as soon as it is falsified. By applying Popper's account of scientific method, John Gray's Straw Dogs states that this would have killed the theories of Darwin and Einstein at birth. When they were first advanced, each of them was at odds with some available evidence; only later did evidence become available that gave them crucial support.

See also

  • Popperian cosmology
    Popperian cosmology
    Popperian cosmology is Karl Popper's philosophical theory of reality that includes three interacting worlds, called World 1, World 2 and World 3...

  • Evolutionary epistemology
    Evolutionary epistemology
    Evolutionary epistemology refers to two distinct topics: it is a subfield of naturalized epistemology as well as a theory in epistemology about the growth of knowledge.- A branch of naturalized epistemology :...

  • Liberalism
    Liberalism
    Liberalism is the belief in the importance of individual freedom. This belief is widely accepted today throughout the world, and was recognized as an important value by many philosophers throughout history...

  • Liberalism in Austria
    Liberalism in Austria
    This article gives an overview of liberalism in Austria. It is limited to liberal parties with substantial support, mainly proved by having had a representation in parliament. The sign ⇒ denotes another party in that scheme...

  • Contributions to liberal theory
    Contributions to liberal theory
    Individual contributors to classical liberalism and political liberalism are strongly associated with philosophers of the Enlightenment. Liberalism as a specifically named ideology begins in the late 18th century as a movement towards self-government and away from aristocracy...

  • Calculus of predispositions
    Calculus of predispositions
    Calculus of Predispositions is a basic part of Predispositioning Theory and belongs to the indeterministic procedures.“The key component of any indeterministic procedure is the evaluation of a position...

  • Predispositioning Theory
    Predispositioning Theory
    Predispositioning Theory in the field of decision theory and systems theory is a theory, that focused on the intermediate stage between a complete order and a complete disorder....

  • Popper's experiment
    Popper's experiment
    Popper's experiment is an experiment proposed by the 20th century philosopher of science Karl Popper, an advocate of strict scientific method who opposed the Copenhagen interpretation, to test that standard interpretation of Quantum mechanics. Popper's experiment is similar in spirit to the thought...

     (quantum mechanics)

Further reading


  • [Comprehensive bibliography:] Lube, Manfred: Karl R. Popper. Bibliographie 1925–2004. Wissenschaftstheorie, Sozialphilosophie, Logik, Wahrscheinlichkeitstheorie, Naturwissenschaften. Frankfurt/Main etc.: Peter Lang, 2005. 576 pp. (Schriftenreihe der Karl Popper Foundation Klagenfurt.3.)
  • Stefano Gattei. Karl Popper's Philosophy of Science. 2009.
  • David Miller
    David Miller (philosopher)
    David W. Miller is a philosopher and prominent exponent of critical rationalism. He teaches in the Department of Philosophy at the University of Warwick in Coventry, UK....

    . Critical Rationalism: A Restatement and Defence. 1994.
  • David Miller
    David Miller (philosopher)
    David W. Miller is a philosopher and prominent exponent of critical rationalism. He teaches in the Department of Philosophy at the University of Warwick in Coventry, UK....

     (Ed.). Popper Selections.
  • John W. N. Watkins. Science and Skepticism. 1984.
  • Bailey, Richard, Education in the Open Society: Karl Popper and Schooling. Aldershot, UK: Ashgate 2000. The only book-length examination of Popper's relevance to education.
  • Bartley, William Warren III. Unfathomed Knowledge, Unmeasured Wealth. La Salle, IL: Open Court Press 1990. A look at Popper and his influence by one of his students.
  • Berkson, William K., and Wettersten, John. Learning from Error: Karl Popper's Psychology of Learning. La Salle, IL: Open Court 1984
  • Edmonds, D., Eidinow, J. Wittgenstein's Poker. New York: Ecco 2001. A review of the origin of the conflict between Popper and Ludwig Wittgenstein
    Ludwig Wittgenstein
    Ludwig Josef Johann Wittgenstein was an Austrian-British philosopher who worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language....

    , focused on events leading up to their volatile first encounter at 1946 Cambridge meeting.
  • Feyerabend, Paul Against Method. London: New Left Books, 1975. A polemical, iconoclastic book by a former colleague of Popper's. Vigorously critical of Popper's rationalist view of science.
  • Hacohen, M. Karl Popper: The Formative Years, 1902 – 1945. Cambridge: Cambridge University Press, 2000.
  • Hickey, J. Thomas. History of the Twentieth-Century Philosophy of Science Book V, Karl Popper And Falsificationist Criticism. www.philsci.com . 1995* Kadvany, John Imre Lakatos and the Guises of Reason. Durham and London: Duke University Press, 2001. ISBN 0-8223-2659-0. Explains how Imre Lakatos developed Popper's philosophy into a historicist and critical theory of scientific method.
  • Kuhn, Thomas S. The Structure of Scientific Revolutions. Chicago: University of Chicago Press, 1962. Central to contemporary philosophy of science is the debate between the followers of Kuhn and Popper on the nature of scientific enquiry. This is the book in which Kuhn's views received their classical statement.
  • Levinson, Paul
    Paul Levinson
    Paul Levinson is an American author and professor of communications and media studies at Fordham University in New York City. Levinson's novels, short fiction, and non-fiction works have been translated into twelve languages....

    , ed. In Pursuit of Truth: Essays on the Philosophy of Karl Popper on the Occasion of his 80th Birthday. Atlantic Highlands, NJ: Humanities Press, 1982. A collection of essays on Popper's thought and legacy by a wide range of his followers. Includes an interview with Sir Ernst Gombrich
    Ernst Gombrich
    Sir Ernst Hans Josef Gombrich, OM, CBE was an Austrian-born art historian who spent most of his working life in the United Kingdom...

    .
  • Magee, Bryan. Popper. London: Fontana, 1977. An elegant introductory text. Very readable, albeit rather uncritical of its subject, by a former Member of Parliament.
  • Magee, Bryan. Confessions of a Philosopher, Weidenfeld and Nicolson, 1997. Magee's philosophical autobiography, with a chapter on his relations with Popper. More critical of Popper than in the previous reference.
  • Munz, Peter. Beyond Wittgenstein's Poker: New Light on Popper and Wittgenstein Aldershot, Hampshire, UK: Ashgate, 2004. ISBN 0-7546-4016-7. Written by the only living student of both Wittgenstein and Popper, an eyewitness to the famous "poker" incident described above (Edmunds & Eidinow). Attempts to synthesize and reconcile the differences between these two philosophers.
  • Niemann, Hans-Joachim
    Hans-Joachim Niemann
    Hans Joachim Niemann, born in 1941 in Kiel on the Baltic Sea, is a German philosopher who has developed the methods of critical rationalism for applying them in the fields of metaphysics and ethics.-Biography:...

    . Lexikon des Kritischen Rationalismus, (Encyclopaedia of Critical Raionalism), 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.
  • Notturno, Mark Amadeus. "Objectivity, Rationality, and the Third Realm: Justification and the Grounds of Psychologism". Boston: Martinus Nijhoff, 1985.
  • Notturno, Mark Amadeus. On Popper. Wadsworth Philosophers Series. 2003. A very comprehensive book on Popper’s philosophy by an accomplished Popperian.
  • Notturno, Mark Amadeus. "Science and the Open Society". New York: CEU Press, 2000.
  • O'Hear, Anthony. Karl Popper. London: Routledge, 1980. A critical account of Popper's thought, viewed from the perspective of contemporary analytic philosophy.
  • Radnitzky, Gerard, Bartley, W. W., III eds. Evolutionary Epistemology, Rationality, and the Sociology of Knowledge. La Salle, IL: Open Court Press 1987. ISBN 0-8126-9039-7. A strong collection of essays by Popper, Campbell, Munz, Flew, et al., on Popper's epistemology and critical rationalism. Includes a particularly vigorous answer to Rorty's criticisms.
  • Richmond, Sheldon. Aesthetic Criteria: Gombrich and the Philosophies of Science of Popper and Polanyi. Rodopi, Amsterdam/Atlanta, 1994, 152 pp. ISBN 90-5183-618-X.
  • Schilpp, Paul A., ed. The Philosophy of Karl Popper, 2 vols. La Salle, IL: Open Court Press, 1974. One of the better contributions to the Library of Living Philosophers series. Contains Popper's intellectual autobiography, a comprehensive range of critical essays, and Popper's responses to them.
  • Schroeder-Heister, P. "Popper, Karl Raimund (1902–94)," International Encyclopedia of the Social & Behavioral Sciences
    International Encyclopedia of the Social & Behavioral Sciences
    The International Encyclopedia of the Social & Behavioral Sciences , edited by Neil J. Smelser andPaul B. Baltes, is a 26-volume work. It has some 4,000 signed articles, commissioned by around 50 subject editors, and includes biographical entries, 122,400 entries, and an extensivehierarchical...

    , 2001, pp. 11727–11733.Abstract.
  • Shearmur, Jeremy. The Political Thought of Karl Popper. London and New York: Routledge, 1996. Study of Popper's political thought by a former assistant of Popper's. Makes use of archive sources and studies the development of Popper's political thought and its inter-connections with his epistemology.
  • Stokes, G. Popper: Philosophy, Politics and Scientific Method. Cambridge: Polity Press, 1998. A very comprehensive, balanced study, which focuses largely on the social and political side of Popper's thought.
  • Stove, D.C.
    David Stove
    David Charles Stove , was an Australian philosopher of science.His work in philosophy of science included detailed criticisms of David Hume's inductive skepticism, as well as what he regarded as the irrationalism of his disciplinary contemporaries Karl Popper, Thomas Kuhn, Imre Lakatos, and Paul...

    , Popper and After
    Popper and After
    Popper and After is a book by David Charles Stove first published by Pergamon Press in 1982. It was subtitled Four Modern Irrationalists...

    : Four Modern Irrationalists
    . Oxford: Pergamon. 1982. A vigorous attack, especially on Popper's restricting himself to deductive logic.
  • Thornton, Stephen. "Karl Popper," Stanford Encyclopedia of Philosophy
    Stanford Encyclopedia of Philosophy
    The Stanford Encyclopedia of Philosophy is a freely-accessible online encyclopedia of philosophy maintained by Stanford University. Each entry is written and maintained by an expert in the field, including professors from over 65 academic institutions worldwide...

    ,
    2006.
  • Weimer, W., Palermo, D., eds. Cognition and the Symbolic Processes. Hillsdale, NJ: Lawrence Erlbaum Associates. 1982. See Hayek's essay, "The Sensory Order after 25 Years", and "Discussion".


External links