Sir Karl Raimund Popper CH FBA FRS (28 July 1902 – 17
September 1994) was an Austrian-British philosopher and
professor. He is generally regarded as one of the 20th
century's greatest philosophers of science.
Popper is known for his rejection of the classical inductivist views
on the scientific method, in favour of empirical falsification: A
theory in the empirical sciences can never be proven, but it can be
falsified, meaning that it can and should be scrutinized by decisive
experiments. Popper is also known for his opposition to the classical
justificationist account of knowledge, which he replaced with critical
rationalism, namely "the first non-justificational philosophy of
criticism in the history of philosophy."
In political discourse, he is known for his vigorous defence of
liberal democracy and the principles of social criticism that he came
to believe made a flourishing open society possible. His political
philosophy embraces ideas from all major democratic political
ideologies and attempts to reconcile them: socialism/social democracy,
libertarianism/classical liberalism and conservatism.
1 Personal life
1.1 Family and training
1.2 Academic life
2 Honours and awards
3.1 Background to Popper's ideas
3.2 Philosophy of science
3.2.1 Falsifiability/problem of demarcation
3.2.2 Falsification/problem of induction
3.4 Philosophy of arithmetic
3.5 Political philosophy
3.5.1 The paradox of tolerance
3.6.2 Cosmological pluralism
3.6.3 Origin and evolution of life
3.6.4 Free will
3.7 Religion and God
8 See also
10 Further reading
11 External links
Family and training
Karl Popper was born in
Vienna (then in Austria-Hungary) in 1902, to
upper middle-class parents. All of Karl Popper's grandparents were
Jewish but were not devout, and as part of the cultural assimilation
process, the Popper family converted to
Lutheranism before Karl was
born, and so he received Lutheran baptism. Karl's
father Simon Siegmund Carl Popper was a lawyer from
Bohemia and a
doctor of law at the
Vienna University, and mother Jenny Schiff was of
Silesian and Hungarian descent. Karl Popper's uncle was the Austrian
philosopher Josef Popper-Lynkeus. After establishing themselves in
Vienna, the Poppers made a rapid social climb in Viennese society:
Simon Siegmund Carl became a partner in the law firm of Vienna's
Raimund Grübl and, after Grübl's death in 1898, Simon
took over the business. Karl received his middle name after Raimund
Grübl. (Popper himself, in his autobiography, erroneously recalls
that Grübl's first name was Carl.) His father was a bibliophile
who had 12,000–14,000 volumes in his personal library and took
an interest in philosophy, the classics, and social and political
issues. Popper inherited both the library and the disposition from
him. Later, he would describe the atmosphere of his upbringing as
having been "decidedly bookish."
Popper left school at the age of 16 and attended lectures in
mathematics, physics, philosophy, psychology and the history of music
as a guest student at the University of Vienna. In 1919, Popper became
Marxism and subsequently joined the Association of
Socialist School Students. He also became a member of the Social
Democratic Workers' Party of Austria, which was at that time a party
that fully adopted the Marxist ideology. After the street battle
in the Hörlgasse on 15 June 1919, when police shot eight of his
unarmed party comrades, he became disillusioned by what he saw as the
"pseudo-scientific" historical materialism of Marx, abandoned the
ideology, and remained a supporter of social liberalism throughout his
He worked in street construction for a short amount of time, but was
unable to cope with the heavy labour. Continuing to attend university
as a guest student, he started an apprenticeship as a cabinetmaker,
which he completed as a journeyman. He was dreaming at that time of
starting a daycare facility for children, for which he assumed the
ability to make furniture might be useful. After that he did voluntary
service in one of psychoanalyst Alfred Adler's clinics for children.
In 1922, he did his matura by way of a second chance education and
finally joined the University as an ordinary student. He completed his
examination as an elementary teacher in 1924 and started working at an
after-school care club for socially endangered children. In 1925, he
went to the newly founded Pädagogisches Institut and continued
studying philosophy and psychology. Around that time he started
courting Josefine Anna Henninger, who later became his wife.
In 1928, he earned a doctorate in psychology, under the supervision of
Karl Bühler. His dissertation was titled "Die Methodenfrage der
Denkpsychologie" (The question of method in cognitive psychology).
In 1929, he obtained the authorisation to teach mathematics and
physics in secondary school, which he started doing. He married his
colleague Josefine Anna Henninger (1906–1985) in 1930. Fearing the
Nazism and the threat of the Anschluss, he started to use the
evenings and the nights to write his first book Die beiden
Grundprobleme der Erkenntnistheorie (The Two Fundamental Problems of
the Theory of Knowledge). He needed to publish one to get some
academic position in a country that was safe for people of Jewish
descent. However, he ended up not publishing the two-volume work, but
a condensed version of it with some new material, Logik der Forschung
Logic of Scientific Discovery), in 1934. Here, he criticised
psychologism, naturalism, inductivism, and logical positivism, and put
forth his theory of potential falsifiability as the criterion
demarcating science from non-science. In 1935 and 1936, he took unpaid
leave to go to the United Kingdom for a study visit.
In 1937, Popper finally managed to get a position that allowed him to
emigrate to New Zealand, where he became lecturer in philosophy at
Canterbury University College
Canterbury University College of the
University of New Zealand
University of New Zealand in
Christchurch. It was here that he wrote his influential work The Open
Society and its Enemies. In Dunedin he met the Professor of Physiology
John Carew Eccles
John Carew Eccles and formed a lifelong friendship with him. In 1946,
after the Second World War, he moved to the United Kingdom to become
reader in logic and scientific method at the
London School of
Economics. Three years later, in 1949, he was appointed professor of
logic and scientific method at the University of London. Popper was
president of the
Aristotelian Society from 1958 to 1959. He retired
from academic life in 1969, though he remained intellectually active
for the rest of his life. In 1985, he returned to
Austria so that his
wife could have her relatives around her during the last months of her
life; she died in November that year. After the Ludwig Boltzmann
Gesellschaft failed to establish him as the director of a newly
founded branch researching the philosophy of science, he went back
again to the United Kingdom in 1986, settling in Kenley, Surrey.
Sir Karl Popper's gravesite in Lainzer Friedhof (de), in Vienna,
Popper died of "complications of cancer, pneumonia and kidney failure"
Kenley at the age of 92 on 17 September 1994. He had been
working continuously on his philosophy until two weeks before, when he
suddenly fell terminally ill. After cremation, his ashes were
Vienna and buried at Lainzer cemetery adjacent to the ORF
Centre, where his wife Josefine Anna Popper (called 'Hennie') had
already been buried. Popper's estate is managed by his secretary
and personal assistant Melitta Mew and her husband Raymond. Popper's
manuscripts went to the
Hoover Institution at Stanford University,
partly during his lifetime and partly as supplementary material after
his death. Klagenfurt University has Popper's library, including his
precious bibliophilia, as well as hard copies of the original Hoover
material and microfilms of the supplementary material. The remaining
parts of the estate were mostly transferred to The Karl Popper
Charitable Trust. In October 2008 Klagenfurt University acquired
the copyrights from the estate.
Popper and his wife chose not to have children because of the
circumstances of war in the early years of their marriage. Popper
commented that this "was perhaps a cowardly but in a way a right
Honours and awards
Sir Karl Popper, Prof. Cyril Höschl. K. Popper received the Honorary
Doctor's degree of
Charles University in Prague
Charles University in Prague (May 1994)
Popper won many awards and honours in his field, including the
Lippincott Award of the American Political Science Association, the
Sonning Prize, the
Otto Hahn Peace Medal of the United Nations
Association of Germany in Berlin and fellowships in the Royal
Society, British Academy,
London School of Economics, King's
College London, Darwin College, Cambridge, Austrian Academy of
Sciences and Charles University, Prague.
Austria awarded him the Grand
Decoration of Honour in Gold for Services to the Republic of Austria
in 1986, and the Federal Republic of Germany its Grand Cross with Star
and Sash of the Order of Merit, and the peace class of the Order Pour
le Mérite. He received the Humanist Laureate Award from the
International Academy of Humanism. He was knighted by Queen
Elizabeth II in 1965, and was elected a Fellow of the Royal
Society in 1976. He was invested with the Insignia of a Companion
of Honour in 1982.
Other awards and recognition for Popper included the City of Vienna
Prize for the
Humanities (1965), Karl Renner Prize (1978), Austrian
Decoration for Science and Art (1980), Dr. Leopold Lucas Prize of the
University of Tübingen
University of Tübingen (1980), Ring of Honour of the City of Vienna
(1983) and the Premio Internazionale of the Italian Federico Nietzsche
Society (1988). In 1989, he was the first awarded with the Prize
International Catalonia for "his work to develope cultural, scientific
and human values all around the world". In 1992, he was awarded
Kyoto Prize in Arts and Philosophy
Kyoto Prize in Arts and Philosophy for "symbolising the open
spirit of the 20th century" and for his "enormous influence on the
formation of the modern intellectual climate".
Main article: Critical rationalism
Background to Popper's ideas
Popper's rejection of
Marxism during his teenage years left a profound
mark on his thought. He had at one point joined a socialist
association, and for a few months in 1919 considered himself a
communist. Although it's known that Popper worked as an office boy
at the communist headquarters, whether or not he ever became a
communist member is unclear. During this time he became familiar
with the Marxist view of economics, class conflict, and history.
Although he quickly became disillusioned with the views expounded by
Marxism, his flirtation with the ideology led him to distance himself
from those who believed that spilling blood for the sake of a
revolution was necessary. He came to realise that when it came to
sacrificing human lives, one was to think and act with extreme
The failure of democratic parties to prevent fascism from taking over
Austrian politics in the 1920s and 1930s traumatised Popper. He
suffered from the direct consequences of this failure, since events
after the Anschluss, the annexation of
Austria by the
German Reich in
1938, forced him into permanent exile. His most important works in the
field of social science—The Poverty of
Historicism (1944) and The
Society and Its Enemies (1945)—were inspired by his reflection
on the events of his time and represented, in a sense, a reaction to
the prevalent totalitarian ideologies that then dominated Central
European politics. His books defended democratic liberalism as a
social and political philosophy. They also represented extensive
critiques of the philosophical presuppositions underpinning all forms
Popper puzzled over the stark contrast between the non-scientific
character of Freud and Adler's theories in the field of psychology and
the revolution set off by Einstein's theory of relativity in physics
in the early 20th century. Popper thought that Einstein's theory, as a
theory properly grounded in scientific thought and method, was highly
"risky", in the sense that it was possible to deduce consequences from
it which were, in the light of the then-dominant Newtonian physics,
highly improbable (e.g., that light is deflected towards solid
bodies—confirmed by Eddington's experiments in 1919), and which
would, if they turned out to be false, falsify the whole theory. In
contrast, nothing could, even in principle, falsify psychoanalytic
theories. He thus came to the conclusion that psychoanalytic theories
had more in common with primitive myths than with genuine science.
This led Popper to conclude that what were regarded[by whom?] as the
remarkable strengths of psychoanalytical theories were actually their
weaknesses. Psychoanalytical theories were crafted in a way that made
them able to refute any criticism and to give an explanation for every
possible form of human behaviour. The nature of such theories made it
impossible for any criticism or experiment—even in principle—to
show them to be false. This realisation had an important
consequence when Popper later tackled the problem of demarcation in
the philosophy of science, as it led him to posit that the strength of
a scientific theory lies in its both being susceptible to
falsification, and not actually being falsified by criticism made of
it. He considered that if a theory cannot, in principle, be falsified
by criticism, it is not a scientific theory.
Philosophy of science
Falsifiability/problem of demarcation
Popper coined the term "critical rationalism" to describe his
philosophy. Concerning the method of science, the term indicates his
rejection of classical empiricism, and the classical
observationalist-inductivist account of science 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 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. To say that a given statement (e.g., the
statement of a law of some scientific theory)—call it "T"—is
"falsifiable" does not mean that "T" is false. Rather, it means that,
if "T" is false, then (in principle), "T" could be shown to be false,
by observation or by experiment. Popper's account of the logical
asymmetry between verification and falsifiability lies at the heart of
his philosophy of science. It also inspired him to take falsifiability
as his criterion of demarcation 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 and contemporary
Marxism to scientific status, on the
basis that their theories are not falsifiable.
Popper also wrote extensively against the famous Copenhagen
interpretation of quantum mechanics. He strongly disagreed with Niels
Bohr's instrumentalism and supported Albert Einstein's realist
approach to scientific theories about the universe. Popper's
falsifiability resembles Charles Peirce's nineteenth century
fallibilism. 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—that is, 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. Again, in this context the word "falsified" does
not refer to something being "fake"; rather, that something can be
(i.e., is capable of being) shown to be false by observation or
experiment. Some things simply do not lend themselves to being shown
to be false, and therefore, are not falsifiable. 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:
displaystyle mathrm PS _ 1 rightarrow mathrm TT _ 1
rightarrow mathrm EE _ 1 rightarrow mathrm PS _ 2 .,
In response to a given problem situation (
displaystyle mathrm PS _ 1
), a number of competing conjectures, or tentative theories (
displaystyle mathrm TT
), are systematically subjected to the most rigorous attempts at
falsification possible. This process, error elimination (
displaystyle mathrm EE
), performs a similar function for science that natural selection
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 (
displaystyle mathrm PS _ 1
). Consequently, just as a species' biological fitness does not ensure
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, over many generations, produced
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 (
displaystyle mathrm PS _ 2
). 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
Falsification/problem of induction
Among his contributions to philosophy is his claim to have solved the
philosophical problem of induction. 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. Nor is it rational
according to Popper to make instead the more complex assumption that
the sun will rise until a given day, but will stop doing so the day
after, 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 the 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 identified as all
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; it is more important that its falsity can be detected as easily
David Hume 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)
Popper held that rationality is not restricted to the realm of
empirical or scientific theories, but that it is merely a special case
of the general method of criticism, the method of finding and
eliminating contradictions in knowledge without ad-hoc-measures.
According to this view, rational discussion about metaphysical ideas,
about moral values and even about purposes is possible. Popper's
student W.W. Bartley III tried to radicalise this idea and made the
controversial claim that not only can criticism go beyond empirical
knowledge, but that everything can be rationally criticised.
To Popper, who was an anti-justificationist, traditional philosophy is
misled by the false principle of sufficient reason. 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 scrutinised. It is not the goal to bless theories
with claims of certainty or justification, but to eliminate errors in
them. He writes, "there are no such things as good positive reasons;
nor do we need such things [...] But [philosophers] obviously cannot
quite bring [themselves] to believe that this is my opinion, let alone
that it is right" (The Philosophy of Karl Popper, p. 1043)
Philosophy of arithmetic
Popper's principle of falsifiability runs into prima facie
difficulties when the epistemological status of mathematics is
considered. It is difficult to conceive how simple statements of
arithmetic, such as "2 + 2 = 4", could ever be shown to be false. If
they are not open to falsification they can not be scientific. If they
are not scientific, it needs to be explained how they can be
informative about real world objects and events.
Popper's solution was an original contribution in the philosophy
of mathematics. His idea was that a number statement such as "2 apples
+ 2 apples = 4 apples" can be taken in two senses. In one sense it is
irrefutable and logically true, in the second sense it is factually
true and falsifiable. Concisely, the pure mathematics "2 + 2 = 4" is
always true, but, when the formula is applied to real world apples, it
is open to falsification.
The Open Society and Its Enemies
The Open Society and Its Enemies and The Poverty of Historicism,
Popper developed a critique of historicism and a defence of the "Open
Society". Popper considered historicism to be the theory that history
develops inexorably and necessarily according to knowable general laws
towards a determinate end. He argued that this view is the principal
theoretical presupposition underpinning most forms of authoritarianism
and totalitarianism. 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 his early years Popper was impressed by Marxism, whether of
Communists or socialists. An event that happened in 1919 had a
profound effect on him: During a riot, caused by the Communists, the
police shot several unarmed people, including some of Popper's
friends, when they tried to free party comrades from prison. The riot
had, in fact, been part of a plan by which leaders of the Communist
party with connections to
Béla Kun tried to take power by a coup;
Popper did not know about this at that time. However, he knew that the
riot instigators were swayed by the Marxist doctrine that class
struggle would produce vastly more dead men than the inevitable
revolution brought about as quickly as possible, and so had no
scruples to put the life of the rioters at risk to achieve their
selfish goal of becoming the future leaders of the working class. This
was the start of his later criticism of historicism. Popper
began to reject Marxist historicism, which he associated with
questionable means, and later socialism, which he associated with
placing equality before freedom (to the possible disadvantage of
In 1947, Popper co-founded the Mont Pelerin Society, with Friedrich
Hayek, Milton Friedman,
Ludwig von Mises
Ludwig von Mises and others, although he did
not fully agree with the think tank's charter and ideology.
Specifically, he unsuccessfully recommended that socialists should be
invited to participate, and that emphasis should be put on a hierarchy
of humanitarian values rather than advocacy of a free market as
envisioned by classical liberalism.
The paradox of tolerance
Main article: Paradox of tolerance
Although Popper was an advocate of toleration, he said that
intolerance should not be tolerated, for if tolerance allowed
intolerance to succeed completely, tolerance would be threatened. In
Society and Its Enemies, he argued:
Unlimited tolerance must lead to the disappearance of tolerance. If we
extend unlimited tolerance even to those who are intolerant, if we are
not prepared to defend a tolerant society against the onslaught of the
intolerant, then the tolerant will be destroyed, and tolerance with
them. In this formulation, I do not imply, for instance, that we
should always suppress the utterance of intolerant philosophies; as
long as we can counter them by rational argument and keep them in
check by public opinion, suppression would certainly be most unwise.
But we should claim the right to suppress them if necessary even by
force; for it may easily turn out that they are not prepared to meet
us on the level of rational argument, but begin by denouncing all
argument; they may forbid their followers to listen to rational
argument, because it is deceptive, and teach them to answer arguments
by the use of their fists or pistols. We should therefore claim, in
the name of tolerance, the right not to tolerate the intolerant. We
should claim that any movement preaching intolerance places itself
outside the law, and we should consider incitement to intolerance and
persecution as criminal, in the same way as we should consider
incitement to murder, or to kidnapping, or to the revival of the slave
trade, as criminal.
As early as 1934, Popper wrote of the search for truth as "one of the
strongest motives for scientific discovery." Still, he describes
Knowledge (1972) early concerns about the much-criticised
notion of truth as correspondence. Then came the semantic theory of
truth formulated by the logician
Alfred Tarski 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 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. 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, 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:
"John called" is true.
"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 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 emphasises
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. Here he defines it as:
displaystyle mathit Vs (a)= mathit CT _ v (a)- mathit CT _
displaystyle mathit Vs (a)
is the verisimilitude of a,
displaystyle mathit CT _ v (a)
is a measure of the content of the truth of a, and
displaystyle mathit CT _ f (a)
is a measure of the content of the falsity of a.
Popper's original attempt to define not just verisimilitude, but an
actual measure of it, turned out to be inadequate. However, it
inspired a wealth of new attempts.
Main article: Popper's three worlds
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: 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, such as
Daniel Dennett, have not embraced Popper's Three World conjecture, due
mostly, it seems, to its resemblance to mind-body dualism.
Origin and evolution of life
This section may be too long to read and navigate comfortably. Please
consider splitting content into sub-articles, condensing it, or adding
or removing subheadings. (January 2018)
The creation–evolution controversy in the United States raises the
issue of whether creationistic ideas may be legitimately called
science and whether evolution itself may be legitimately called
science. In the debate, both sides and even courts in their decisions
have frequently invoked Popper's criterion of falsifiability (see
Daubert standard). In this context, passages written by Popper are
frequently quoted in which he speaks about such issues himself. For
example, he famously stated "
Darwinism is not a testable scientific
theory, but a metaphysical research program—a possible framework for
testable scientific theories." He continued:
And yet, the theory is invaluable. I do not see how, without it, our
knowledge could have grown as it has done since Darwin. In trying to
explain experiments with bacteria which become adapted to, say,
penicillin, it is quite clear that we are greatly helped by the theory
of natural selection. Although it is metaphysical, it sheds much light
upon very concrete and very practical researches. It allows us to
study adaptation to a new environment (such as a penicillin-infested
environment) in a rational way: it suggests the existence of a
mechanism of adaptation, and it allows us even to study in detail the
mechanism at work.
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".
Popper later said:
When speaking here of Darwinism, I shall speak always of today's
theory—that is Darwin's own theory of natural selection supported by
the Mendelian theory of heredity, by the theory of the mutation and
recombination of genes in a gene pool, and by the decoded genetic
code. This is an immensely impressive and powerful theory. The claim
that it completely explains evolution is of course a bold claim, and
very far from being established. All scientific theories are
conjectures, even those that have successfully passed many severe and
varied tests. The Mendelian underpinning of modern
Darwinism has been
well tested, and so has the theory of evolution which says that all
terrestrial life has evolved from a few primitive unicellular
organisms, possibly even from one single organism.
In 1974, regarding DNA and the origin of life he said:
What makes the origin of life and of the genetic code a disturbing
riddle is this: the genetic code is without any biological function
unless it is translated; that is, unless it leads to the synthesis of
the proteins whose structure is laid down by the code. But, as Monod
points out, the machinery by which the cell (at least the
non-primitive cell, which is the only one we know) translates the code
"consists of at least fifty macromolecular components which are
themselves coded in the DNA". (Monod, 1970; 1971, 143).
Thus the code can not be translated except by using certain products
of its translation. This constitutes a really baffling circle; a
vicious circle, it seems, for any attempt to form a model, or theory,
of the genesis of the genetic code.
Thus we may be faced with the possibility that the origin of life
(like the origin of the universe) becomes an impenetrable barrier to
science, and a residue to all attempts to reduce biology to chemistry
He explained that the difficulty of testing had led some people to
describe natural selection as a tautology, 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:
My solution was that the doctrine of natural selection is a most
successful metaphysical research programme. It raises detailed
problems in many fields, and it tells us what we would expect of an
acceptable solution of these problems. I still believe that natural
selection works in this way as a research programme. Nevertheless, I
have changed my mind about the testability and logical status of the
theory of natural selection; and I am glad to have an opportunity to
make a recantation.
Popper summarized his new view as follows:
The theory of natural selection may be so formulated that it is far
from tautological. In this case it is not only testable, but it turns
out to be not strictly universally true. There seem to be exceptions,
as with so many biological theories; and considering the random
character of the variations on which natural selection operates, the
occurrence of exceptions is not surprising. Thus not all phenomena of
evolution are explained by natural selection alone. Yet in every
particular case it is a challenging research program to show how far
natural selection can possibly be held responsible for the evolution
of a particular organ or behavioural program.
These frequently quoted passages are only a very small part of what
Popper wrote on the issue of evolution, however, and give the wrong
impression that he mainly discussed questions of its falsifiability.
Popper never invented this criterion to give justifiable use of words
like science. In fact, Popper stresses at the beginning of
Scientific Discovery that "the last thing I wish to do, however, is to
advocate another dogma" and that "what is to be called a 'science'
and who is to be called a 'scientist' must always remain a matter of
convention or decision." He quotes Menger's dictum that
"Definitions are dogmas; only the conclusions drawn from them can
afford us any new insight" and notes that different definitions of
science can be rationally debated and compared:
I do not try to justify [the aims of science which I have in mind],
however, by representing them as the true or the essential aims of
science. This would only distort the issue, and it would mean a
relapse into positivist dogmatism. There is only one way, as far as I
can see, of arguing rationally in support of my proposals. This is to
analyse their logical consequences: to point out their
fertility—their power to elucidate the problems of the theory of
Popper had his own sophisticated views on evolution that go much
beyond what the frequently-quoted passages say. In effect, Popper
agreed with some of the points of both creationists and naturalists,
but also disagreed with both views on crucial aspects. Popper
understood the universe as a creative entity that invents new things,
including life, but without the necessity of something like a god,
especially not one who is pulling strings from behind the curtain. He
said that evolution of the genotype must, as the creationists say,
work in a goal-directed way but disagreed with their view that it
must necessarily be the hand of god that imposes these goals onto the
stage of life.
Instead, he formulated the spearhead model of evolution, a version of
genetic pluralism. According to this model, living organisms
themselves have goals, and act according to these goals, each guided
by a central control. In its most sophisticated form, this is the
brain of humans, but controls also exist in much less sophisticated
ways for species of lower complexity, such as the amoeba. This control
organ plays a special role in evolution—it is the "spearhead of
evolution". The goals bring the purpose into the world. Mutations in
the genes that determine the structure of the control may then cause
drastic changes in behaviour, preferences and goals, without having an
impact on the organism's phenotype. Popper postulates that such purely
behavioural changes are less likely to be lethal for the organism
compared to drastic changes of the phenotype.
Popper contrasts his views with the notion of the "hopeful monster"
that has large phenotype mutations and calls it the "hopeful
behavioural monster". After behaviour has changed radically, small but
quick changes of the phenotype follow to make the organism fitter to
its changed goals. This way it looks as if the phenotype were changing
guided by some invisible hand, while it is merely natural selection
working in combination with the new behaviour. For example, according
to this hypothesis, the eating habits of the giraffe must have changed
before its elongated neck evolved. Popper contrasted this view as
"evolution from within" or "active Darwinism" (the organism actively
trying to discover new ways of life and being on a quest for
conquering new ecological niches), with the naturalistic
"evolution from without" (which has the picture of a hostile
environment only trying to kill the mostly passive organism, or
perhaps segregate some of its groups).
Popper was a key figure encouraging patent lawyer Günter
Wächtershäuser to publish his
Iron–sulfur world theory on
abiogenesis and his criticism of "soup" theory.
About the creation-evolution controversy itself, Popper initially
wrote that he considered it "a somewhat sensational clash between a
brilliant scientific hypothesis concerning the history of the various
species of animals and plants on earth, and an older metaphysical
theory which, incidentally, happened to be part of an established
religious belief" with a footnote to the effect that he "agree[s] with
Professor C.E. Raven when, in his Science, Religion, and the Future,
1943, he calls this conflict 'a storm in a Victorian tea-cup'; though
the force of this remark is perhaps a little impaired by the attention
he pays to the vapours still emerging from the cup—to the Great
Systems of Evolutionist Philosophy, produced by Bergson, Whitehead,
Smuts, and others." In his later work, however, when he had
developed his own "spearhead model" and "active Darwinism" theories,
Popper revised this view and found some validity in the controversy:
I have to confess that this cup of tea has become, after all, my cup
of tea; and with it I have to eat humble pie.
Popper and John Eccles speculated on the problem of free will for many
years, generally agreeing on an interactionist dualist theory of mind.
However, although Popper was a body-mind dualist, he did not think
that the mind is a substance separate from the body: he thought that
mental or psychological properties or aspects of people are distinct
from physical ones.
When he gave the second
Arthur Holly Compton
Arthur Holly Compton Memorial Lecture in 1965,
Popper revisited the idea of quantum indeterminacy 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
criticised 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, together with many of his views on the
subject, from Hume, 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, saying, "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 characterised 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
Religion and God
In an interview that Popper gave in 1969 with the condition that
it should be kept secret until after his death, he summarised his
position on God as follows: "I don't know whether God exists or not.
... Some forms of atheism are arrogant and ignorant and should be
rejected, but agnosticism—to admit that we don't know and to
search—is all right. ... When I look at what I call the gift of
life, I feel a gratitude which is in tune with some religious ideas of
God. However, the moment I even speak of it, I am embarrassed that I
may do something wrong to God in talking about God." He objected to
organised religion, saying "it tends to use the name of God in vain",
noting the danger of fanaticism because of religious conflicts: "The
whole thing goes back to myths which, though they may have a kernel of
truth, are untrue. Why then should the Jewish myth be true and the
Indian and Egyptian myths not be true?" In a letter unrelated to the
interview, he stressed his tolerant attitude: "Although I am not for
religion, I do think that we should show respect for anybody who
Karl Popper in 1990
Popper played a vital role in establishing the philosophy of science
as a vigorous, autonomous discipline within philosophy, 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 and there lectured and influenced both Imre
Lakatos and Paul Feyerabend, two of the foremost philosophers of
science in the next generation of philosophy of science. (Lakatos
significantly modified Popper's position,:1 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,
who was also brought to the
London School of Economics from Vienna.
Each found support and similarities in the 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." Popper
Conjectures and Refutations
Conjectures and Refutations 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."
Popper also had long and mutually influential friendships with art
historian Ernst Gombrich, biologist Peter Medawar, and neuroscientist
John Carew Eccles. The German jurist
Reinhold Zippelius uses Popper's
method of "trial and error" in his legal philosophy.
Popper's influence, both through his work in philosophy of science and
through his political philosophy, has also extended beyond the
academy. One of Popper's students at the
London School of Economics
was George Soros, who later became a billionaire investor, and among
whose philanthropic foundations is the Open
Society Institute, a
think-tank named in honour of Popper's The Open
Society and Its
Most criticisms of Popper's philosophy are of the falsification, or
error elimination, element in his account of problem solving. Popper
presents falsifiability as both an ideal and as an important principle
in a 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
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 recommended as an essential principle of methodology
that, if enacted by a system or community, will 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, the followers of which mistook his aims for their
The Quine-Duhem thesis 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: when the motion of
Uranus 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 and 4 of The
Logic of Scientific
Discovery. 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".[dubious –
Thomas Kuhn, in his influential book The Structure of Scientific
Revolutions, argued that scientists work in a series of paradigms, and
that falsificationist methodologies would make science impossible:
No theory ever solves all the puzzles with which it is confronted at a
given time; nor are the solutions already achieved often perfect. On
the contrary, it is just the incompleteness and imperfection of the
existing data-theory fit that, at any given time, define many of the
puzzles that characterize normal science. If any and every failure to
fit were ground for theory rejection, all theories ought to be
rejected at all times. On the other hand, if only severe failure to
fit justifies theory rejection, then the Popperians will require some
criterion of "improbability" or of "degree of falsification". In
developing one they will almost certainly encounter the same network
of difficulties that has haunted the advocates of the various
probabilistic verification theories [that the evaluative theory cannot
itself be legitimated without appeal to another evaluative theory,
leading to regress]
Imre Lakatos 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 of naïve falsificationism. Another of Popper's
Paul Feyerabend ultimately rejected any prescriptive
methodology, and argued that the only universal method characterising
scientific progress was anything goes.
Popper claimed to have recognised already in the 1934 version of his
Logic of Discovery a fact later stressed by Kuhn, "that scientists
necessarily develop their ideas within a definite theoretical
framework", and to that extent to have anticipated Kuhn's central
point about "normal science". (But Popper criticised what he saw
as Kuhn's relativism.) Also, in his collection Conjectures and
Refutations: 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
criteria to evaluate a null hypothesis. 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 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
In a book called Science Versus Crime, Houck writes that Popper's
falsificationism can be questioned logically: it is not clear how
Popper would deal with a statement like "for every metal, there is a
temperature at which it will melt." The hypothesis cannot be falsified
by any possible observation, for there will always be a higher
temperature than tested at which the metal may in fact melt, yet it
seems to be a valid scientific hypothesis. These examples were pointed
out by Carl Gustav Hempel. 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 implies that all metals melt at some temperature.
An early adversary of Popper's critical rationalism, Karl-Otto Apel
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.
Charles Taylor accuses Popper of exploiting his worldwide fame as an
epistemologist to diminish the importance of philosophers of the 20th
century continental tradition. According to Taylor, Popper's
criticisms are completely baseless, but they are received with an
attention and respect that Popper's "intrinsic worth hardly
In 2004, philosopher and psychologist Michel ter Hark (Groningen, The
Netherlands) published a book, called Popper,
Otto Selz and the rise
of evolutionary epistemology, in which he claimed that Popper took
some of his ideas from his tutor, the German psychologist Otto Selz.
Selz never published his ideas, partly because of the rise of Nazism,
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 criticised in some academic quarters for his rejection
of Plato, Hegel and Marx.
According to John N. Gray, Popper held that "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, Gray's Straw Dogs states that this would have "killed the
theories of Darwin and Einstein at birth." When they were first
advanced, Gray claims, each of them was "at odds with some available
evidence; only later did evidence become available that gave them
crucial support." Against this, Gray seeks to establish the
irrationalist thesis that "the progress of science comes from acting
Gray does not, however, give any indication of what available evidence
these theories were at odds with, and his appeal to "crucial support"
illustrates the very inductivist approach to science that Popper
sought to show was logically illegitimate. For, according to Popper,
Einstein's theory was at least equally as well corroborated as
Newton's upon its initial conception; they both equally well accounted
for all the hitherto available evidence. Moreover, since Einstein also
explained the empirical refutations of Newton's theory, general
relativity was immediately deemed suitable for tentative acceptance on
the Popperian account. Indeed, Popper wrote, several decades
before Gray's criticism, in reply to a critical essay by Imre Lakatos:
It is true that I have used the terms "elimination", and even
"rejection" when discussing "refutation". But it is clear from my main
discussion that these terms mean, when applied to a scientific theory,
that it is eliminated as a contender for the truth—that is, refuted,
but not necessarily abandoned. Moreover, I have often pointed out that
any such refutation is fallible. It is a typical matter of conjecture
and of risk-taking whether or not we accept a refutation and,
furthermore, of whether we "abandon" a theory or, say, only modify it,
or even stick to it, and try to find some alternative, and
methodologically acceptable, way round the problem involved. That I do
not conflate even admitted falsity with the need to abandon a theory
may be seen from the fact that I have frequently pointed out, that
Einstein regarded general relativity as false, yet as a better
approximation to the truth than Newton's gravitational theory. He
certainly did not "abandon" it. But he worked to the end of his life
in an attempt to improve upon it by way of a further
The Two Fundamental Problems of the Theory of Knowledge, 1930–33 (as
a typescript circulating as Die beiden Grundprobleme der
Erkenntnistheorie; as a German book 1979, as English translation
2008), ISBN 0-415-39431-7
Logic of Scientific Discovery, 1934 (as Logik der Forschung,
English translation 1959), ISBN 0-415-27844-9
The Poverty of Historicism, 1936 (private reading at a meeting in
Brussels, 1944/45 as a series of journal articles in Econometrica,
1957 a book), ISBN 0-415-06569-0
Society and Its Enemies, 1945 Vol 1 ISBN 0-415-29063-5,
Vol 2 ISBN 0-415-29063-5
Quantum Theory and the Schism in Physics, 1956/57 (as privately
circulated galley proofs; published as a book 1982),
The Open Universe: An Argument for Indeterminism, 1956/57 (as
privately circulated galley proofs; published as a book 1982),
Realism and the Aim of Science, 1956/57 (as privately circulated
galley proofs; published as a book 1983), ISBN 0-09-151450-9
Conjectures and Refutations: The Growth of Scientific Knowledge, 1963,
Objective Knowledge: An Evolutionary Approach, 1972, Rev. ed., 1979,
Unended Quest: An Intellectual Autobiography, 2002 .
ISBN 0-415-28589-5 (ISBN 0-415-28590-9)
The Self and Its Brain: An Argument for Interactionism (with Sir John
C. Eccles), 1977, ISBN 0-415-05898-8
In Search of a Better World, 1984, ISBN 0-415-13548-6
Die Zukunft ist offen (The Future is Open) (with Konrad Lorenz), 1985
(in German), ISBN 3-492-00640-X
A World of Propensities, 1990, ISBN 1-85506-000-0
The Lesson of this Century, (Interviewer: Giancarlo Bosetti, English
translation: Patrick Camiller), 1992, ISBN 0-415-12958-3
All life is Problem Solving, 1994, ISBN 0-415-24992-9
The Myth of the Framework: In Defence of Science and Rationality
(edited by Mark Amadeus Notturno) 1994. ISBN 0-415-13555-9
Knowledge and the Mind-Body Problem: In Defence of Interaction (edited
by Mark Amadeus Notturno) 1994 ISBN 0-415-11504-3
The World of Parmenides, Essays on the Presocratic Enlightenment,
1998, (Edited by Arne F. Petersen with the assistance of Jørgen
Mejer), ISBN 0-415-17301-9
After The Open Society, 2008. (Edited by
Jeremy Shearmur and Piers
Norris Turner, this volume contains a large number of Popper's
previously unpublished or uncollected writings on political and social
themes.) ISBN 978-0-415-30908-0
Frühe Schriften, 2006 (Edited by Troels Eggers Hansen, includes
Popper's writings and publications from before the Logic, including
his previously unpublished thesis, dissertation and journal articles
published that relate to the Wiener Schulreform)
Interview Karl Popper, Open Universiteit, 1988.
Philosophy of science
Philosophy of science portal
Calculus of predispositions
Contributions to liberal theory
Critique of psychoanalysis
Liberalism in Austria
Poper Scientific Stand up
^ Thornton, Stephen (2015-01-01). Zalta, Edward N., ed. Karl Popper
(Winter 2015 ed.). ("Popper professes to be
anti-conventionalist, and his commitment to the correspondence theory
of truth places him firmly within the realist's camp.")
^ "Cartesianism (philosophy): Contemporary influences" in Britannica
^ Hacohen, Malachi Haim.
Karl Popper – The Formative Years,
1902–1945: Politics and Philosophy in Interwar Vienna. Cambridge
University Press, 2000. pp. 83–85.
^ Thomas S. Kuhn, The Structure of Scientific Revolutions. Chicago and
London: University of Chicago Press, 1970 (2nd ed.), p. 146.
^ Michael Redhead, From
Physics to Metaphysics, Cambridge University
Press, 1996, p. 15.
^ Roger Penrose, Shadows of the Mind, Oxford University Press, 1994.
^ a b c d e Miller, D. (1997). "Sir Karl Raimund Popper, C. H., F. B.
A. 28 July 1902 – 17 September 1994.: Elected F.R.S. 1976".
Biographical Memoirs of Fellows of the Royal Society. 43: 369–409.
^ Watkins, J. (1996). "Obituary of Karl Popper, 1902–1994".
Proceedings of the British Academy. 94: 645–84.
Karl Popper (1902–94) advocated by Andrew Marr BBC In Our Time –
Greatest Philosopher, Retrieved Jan 2015
^ Adams, I.; Dyson, R.W., Fifty Major Political Thinkers, Routledge,
2007, p. 196. "He became a British citizen in 1945".
^ a b c d e f g h i j Thornton, Stephen (2015-01-01). Zalta, Edward
Karl Popper (Winter 2015 ed.).
^ Horgan, J (1992). "Profile: Karl R. Popper – The Intellectual
Warrior". Scientific American. 267 (5): 38–44.
^ Shea, B. "Popper, Karl: Philosophy of Science", in Internet
Encyclopedia of Philosophy, James Feiser (ed.) and Bradley Dowden
(ed.). Retrieved 10 Feb 2016.
^ William W. Bartley:
Rationality versus the Theory of Rationality, In
Mario Bunge: The Critical Approach to Science and Philosophy (The Free
Press of Glencoe, 1964), section IX.
^ "Karl Popper: Political Philosophy [Internet Encyclopedia of
Philosophy]". Iep.utm.edu. 2 August 2013. Retrieved 12 August
^ a b Malachi Haim Hacohen.
Karl Popper – The Formative Years,
1902–1945: Politics and Philosophy in Interwar Vienna. Cambridge:
Cambridge University Press, 2001. pp. 10 & 23,
^ Magee, Bryan. The Story of Philosophy. New York: DK Publishing,
2001. p. 221, ISBN 0-7894-3511-X
^ "Eichstätter Karl Popper-Seite". Helmut-zenz.de. Retrieved 21
^ Karl Popper: Kritischer Rationalismus und Verteidigung der offenen
Gesellschaft. In Josef Rattner, Gerhard Danzer (Eds.): Europäisches
Österreich: Literatur- und geistesgeschichtliche Essays über den
Zeitraum 1800–1980, p. 293
^ Karl R. Popper ( 2002. Unended Quest: An Intellectual
Autobiography, p. 6.
^ Raphael, F. The Great Philosophers London: Phoenix, p. 447,
^ Manfred Lube: Karl R. Popper – Die Bibliothek des Philosophen als
Spiegel seines Lebens. Imprimatur. Ein Jahrbuch für Bücherfreunde.
Neue Folge Band 18 (2003), S. 207–38, ISBN 3-447-04723-2.
^ "Cf. Thomas Sturm: "Bühler and Popper: Kantian therapies for the
crisis in psychology," in: Studies in History and Philosophy of
Biological and Biomedical Sciences, 43 (2012), pp. 462–72".
Retrieved 21 December 2012.
A. C. Ewing was responsible for Karl Popper's 1936 invitation to
Cambridge (Edmonds and Eidinow 2001, p. 67).
Karl Popper Is Dead at 92.
Philosopher of 'Open Society'". New
York Times. 18 September 1994. Retrieved 15 November 2012. Sir Karl
Popper, a philosopher who was a defender of democratic systems of
government, died today in a hospital here. He was 92. He died of
complications of cancer, pneumonia and kidney failure, said a manager
at the hospital in this
^ "Opensociety.de". Opensociety.de. Retrieved 12 August 2014.
^ "David Miller". Fs1.law.keio.ac.jp. 17 September 1994. Retrieved 21
Karl Popper at Find a Grave
Karl Popper Charitable Trust". OpenCharities. 10 September
2012. Retrieved 21 December 2012.
^ a b Edward Zerin:
Karl Popper On God: The Lost Interview. Skeptic
^ "The International Academy of Humanism". Secularhumanism.org.
Retrieved 12 August 2014.
London Gazette". 5 March 1965. p. 22. Retrieved 1 December
London Gazette". 12 June 1982. p. 5. Retrieved 1 December
Karl Popper recoge hoy en Barcelona el Premi Internacional
Catalunya". El País. 24 May 1989.
^ a b "Karl Raimund Popper". Inamori Foundation. Archived from the
original on 23 May 2013. Retrieved 9 June 2012.
^ Ian Charles Jarvie; Karl Milford; David W. Miller (2006). Karl
Popper: A Centenary Assessment Volume I. Ashgate Publishing, Ltd.
pp. 129–. ISBN 978-0-7546-5375-2.
^ Malachi Haim Hacohen (4 March 2002). Karl Popper. The Formative
Years. 1902–1945: Politics and Philosophy in Interwar Vienna.
Cambridge University Press. p. 81.
^ One of the severest critics of Popper's so-called demarcation thesis
was Adolf Grünbaum, cf. Is
Falsifiability the Touchstone of
Scientific Rationality? (1976), and The Degeneration of Popper's
Theory of Demarcation (1989), both in his Collected Works (edited by
Thomas Kupka), vol. I, New York: Oxford University Press 2013, ch. 1
(pp. 9–42) & ch. 2 (pp. 43–61).
^ Popper, Karl Raimund (1946)
Aristotelian Society Supplementary
^ Gregory, Frank Hutson (1996) Arithmetic and Reality: A Development
of Popper's Ideas. City University of Hong Kong. Republished in
Philosophy of Mathematics Education Journal No. 26 (December 2011).
^ The Poverty of Historicism, p. 21
^ Hacohen, p. 82. Books.google.com. 2002-03-04.
ISBN 9780521890557. Retrieved 12 August 2014.
^ Popper, K., All Life is Problem Solving, Routledge, 2013, Ch. 12.
Books.google.co.uk. 15 April 2013. ISBN 9781135973056. Retrieved
12 August 2014.
^ Popper, Karl R. ( 2002). Unended Quest: An Intellectual
Autobiography, pp. 32 -37
^ "Popper argued that some socialists ought to be invited to
participate", "Well I do believe that in a way one has to have a free
market, but I also believe that to make a godhead out of the principle
of the free market is nonsense ... [the free market] is not of a
fundamental importance. Humanitarianism, that is of fundamental
importance" Daniel Stedman Jones: Masters of the Universe: Hayek,
Friedman, and the Birth of Neoliberal Politics, pp. 40 ff.
^ The Open
Society and Its Enemies: The Spell of
Plato by Karl Raimund
Popper, Volume 1, 1947, George Routledge & sons, ltd., p. 226,
Notes to chapter 7:
^ The Open
Society and Its Enemies: The Spell of Plato, by Karl
Raimund Popper, Princeton University Press, 1971,
ISBN 0-691-01968-1, p. 265
^ The Open
Society And Its Enemies, Complete: Volumes I and II, Karl
R. Popper, 1962, Fifth edition (revised), 1966, (PDF)
^ The Open
Society and Its Enemies, p. 581
^ "Karl Popper, the enemy of certainty, part 1: a rejection of
empiricism". The Guardian. Retrieved 22 February 2014.
^ Karl Popper, Three Worlds, The Tanner Lecture on Human Values, The
University of Michigan, 1978.
Unended Quest ch. 37 – see Bibliography
^ a b c "CA211.1: Popper on natural selection's testability".
talk.origins. 2 November 2005. Retrieved 26 May 2009.
^ Le Hasard et la Nécessité. Editions du Seuil, Paris.
^ Chance and Necessity. Knopf, New York
^ Studies in the Philosophy of Biology: Reduction and Related Problems
– Google Books. Books.google.com. 1974. ISBN 9780520026490.
Retrieved 18 October 2015.
^ Evolutionary Epistemology, Rationality, and the
Knowledge – Gerard Radnitzky – Google Books. Books.google.com.
1987. ISBN 9780812690392. Retrieved 12 August 2014.
^ LScD, preface to the first english edition
^ LScD, section 10
^ LScD, section 11
^ LScD, section 4
^ Niemann, Hans-Joachim:
Karl Popper and the Two New Secrets of Life:
Including Karl Popper's Medawar Lecture 1986 and Three Related Texts.
Tubingen: Mohr Siebeck, 2014. ISBN 978-3161532078.
^ For a secondary source see H. Keuth: The philosophy of Karl Popper,
section 15.3 "World 3 and emergent evolution". See also John Watkins:
Popper and Darwinism. The Power of Argumentation (Ed Enrique Suárez
Iñiguez). Primary sources are, in particular,
Objective Knowledge: An evolutionary approach, section "Evolution and
the Tree of Knowledge";
Evolutionary epistemology (Eds. G. Radnitzsky, W.W. Bartley), section
Natural selection and the emergence of mind";
In search of a better world, section "
Knowledge and the shaping of
rationality: the search for a better world", p. 16;
Knowledge and the Body-
Mind Problem: In Defence of Interaction,
section "World 3 and emergent evolution";
A world of propensities, section "Towards an evolutionary theory of
The Self and Its Brain: An Argument for Interactionism (with John C.
Eccles), sections "The biological approach to human knowledge and
intelligence" and "The biological function of conscious and
^ D. W. Miller: Karl Popper, a scientific memoir. Out of Error, p. 33
^ K. Popper: Objective Knowledge, section "Evolution and the Tree of
Knowledge", subsection "Addendum. The Hopeful Behavioural Monster" (p.
^ "Philosophical confusion? – Science Frontiers".
Science-frontiers.com. 2 October 1986. Retrieved 12 August 2014.
^ Michel Ter Hark: Popper,
Otto Selz and the Rise Of Evolutionary
Epistemology, pp. 184 ff
^ Karl R. Popper, The Poverty of Historicism, p. 97
^ Section XVIII, chapter "Of Clouds and Clocks" of Objective
^ Popper, K. R. "Of Clouds and Clocks," in his Objective Knowledge,
corrected edition, pp. 206–55, Oxford, Oxford University Press
(1973), p. 231 footnote 43, & p. 252; also Popper, K. R. "Natural
Selection and the Emergence of Mind", 1977.
^ Popper, K. R. "Of Clouds and Clocks," in: Objective Knowledge,
corrected edition, p. 227, Oxford, Oxford University Press (1973).
Popper's Hume quote is from Treatise on Human Understanding, (see note
8) Book I, Part I, Section XIV, p. 171
^ Of Clouds and Clocks, in Objective Knowledge: An Evolutionary
Approach, Oxford (1972) pp. 227 ff.
^ ibid, p. 232
^ Eccles, John C. and Karl Popper. The Self and Its Brain: An Argument
for Interactionism, Routledge (1984)
^ Popper archives fasc. 297.11
^ See also Karl Popper: On freedom. All life is problem solving
(1999), chapter 7, pp. 81 ff
^ Kadvany, John (2001).
Imre Lakatos and the Guises of Reason. Duke
University Press Books. p. 400. ISBN 978-0-8223-2660-1.
Retrieved 22 January 2016. Site on Lakatos/Popper John Kadvany,
^ Hacohen, 2000
^ Weimer and Palermo, 1982
^ Reinhold Zippelius, Die experimentierende Methode im Recht, 1991
(ISBN 3-515-05901-6), and Rechtsphilosophie, 6th ed., 2011
^ Soros, George (2006). The Age of Fallibility. NY: Public Affairs.
Bryan Magee 1973: Popper (Modern Masters series)
^ Kuhn, Thomas (1970). The Structure of Scientific Revolutions.
Chicago: University of Chicago Press.
^ K R Popper (1970), "Normal Science and its Dangers", pp. 51–58 in
I Lakatos & A Musgrave (eds.) (1970), at p. 51.
^ K R Popper (1970), in I Lakatos & A Musgrave (eds.) (1970), at
^ Popper, Karl, (1934) Logik der Forschung, Springer. Vienna.
Amplified English edition, Popper (1959), ISBN 0-415-27844-9
^ Houck, Max M., Science Versus Crime, Infobase Publishing, 2009, p.
^ See: "Apel, Karl-Otto," La philosophie de A a Z, by Elizabeth
Clement, Chantal Demonque, Laurence Hansen-Love, and Pierre Kahn,
Paris, 1994, Hatier, 19–20. See Also: Towards a Transformation of
Philosophy (Marquette Studies in Philosophy, No 20), by Karl-Otto
Apel, trans., Glyn Adey and David Fisby, Milwaukee, 1998, Marquette
^ Taylor, Charles, "Overcoming Epistemology", in Philosophical
Arguments, Harvard University Press, 1995, ISBN 0-674-66477-9
^ See: "Popper is committing a serious historical error in attributing
the organic theory of the state to
Plato and accusing him of all the
fallacies of post-Hegelian and Marxist historicism—the theory that
history is controlled by the inexorable laws governing the behavior of
superindividual social entities of which human beings and their free
choices are merely subordinate manifestations." Plato's Modern Enemies
and the Theory of Natural Law, by John Wild, Chicago, 1964, The
University of Chicago Press, 23. See Also: "In spite of the high
rating one must accord his initial intention of fairness, his hatred
for the enemies of the 'open society,' his zeal to destroy whatever
seems to him destructive of the welfare of mankind, has led him into
the extensive use of what may be called terminological
counterpropaganda ..." and "With a few exceptions in Popper's favor,
however, it is noticeable that reviewers possessed of special
competence in particular fields—and here Lindsay is again to be
included—have objected to Popper's conclusions in those very fields
..." and "Social scientists and social philosophers have deplored his
radical denial of historical causation, together with his espousal of
Hayek's systematic distrust of larger programs of social reform;
historical students of philosophy have protested his violent polemical
handling of Plato, Aristotle, and particularly Hegel; ethicists have
found contradictions in the ethical theory ('critical dualism') upon
which his polemic is largely based." In Defense of Plato, by Ronald B.
Levinson, New York, 1970, Russell and Russell, 20.
^ a b c Gray, John (2002). Straw Dogs. Granta Books, London.
p. 22. ISBN 1-86207-512-3.
^ Karl Popper, "Replies to my Critics," The Philosophy of Karl Popper,
Paul A. Schilpp, ed., v. II. Archived 4 December 2015 at the Wayback
Machine. Open Court, London, 1974.
^ Karl Popper, "Replies to my Critics," The Philosophy of Karl Popper,
Paul A. Schilpp, ed., v. 2, p. 1009. Archived 4 December 2015 at the
Wayback Machine. Open Court, London, 1974.
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.) (Current edition)
Gattei, Stefano. Karl Popper's Philosophy of Science. 2009.
Miller, David. Critical Rationalism: A Restatement and Defence. 1994.
David Miller (Ed.). Popper Selections.
Watkins, John W. N.. Science and Scepticism. Preface & Contents.
Princeton 1984 (Princeton University Press).
Jarvie, Ian Charles, Karl Milford, David W. Miller, ed. (2006). Karl
Popper: A Centenary Assessment, Ashgate.
Volume I: Life and Times, and Values in a World of Facts. Description
Epistemology Description & Contents.
Volume III: Science. Description & Contents.
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
Psychology of Learning. La Salle, IL: Open Court 1984
Cornforth, Maurice. (1977): The open philosophy and the open society,
2., (rev.) ed., Lawrence & Wishart, London.
ISBN 0-85315-384-1. The fundamental critique from the Marxist
Edmonds, D., Eidinow, J. Wittgenstein's Poker. New York: Ecco 2001. A
review of the origin of the conflict between Popper and Ludwig
Wittgenstein, 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
Imre Lakatos and the Guises of Reason. Durham and
London: Duke University Press, 2001. ISBN 0-8223-2659-0. Explains
Imre Lakatos developed Popper's philosophy into a historicist and
critical theory of scientific method.
Keuth, Herbert. The Philosophy of Karl Popper. Cambridge: Cambridge
University Press, 2004. An accurate scholarly overview of Popper's
philosophy, ideal for students.
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.
Lakatos, I & Musgrave, A (eds.) (1970), Criticism and the Growth
of Knowledge, Cambridge (Cambridge University Press).
Levinson, Paul, ed. In Pursuit of Truth: Essays on the Philosophy of
Karl Popper on the Occasion of his 80th Birthday. Atlantic Highlands,
Humanities Press, 1982. ISBN 0-391-02609-7 A collection of
essays on Popper's thought and legacy by a wide range of his
followers. With forewords by Isaac Asimov and Helmut Schmidt. Includes
an interview with Sir Ernst Gombrich.
Lindh, Allan Goddard (11 November 1993). "Did Popper solve Hume's
problem?". Nature. 366 (6451): 105–06. Bibcode:1993Natur.366..105G.
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
Maxwell, Nicholas, Karl Popper, Science and Enlightenment, London, UCL
Press, 2017. An exposition and development of Popper's philosophy of
science and social philosophy, available free online.
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. 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
Notturno, Mark Amadeus. "Science and the Open Society". New York: CEU
O'Hear, Anthony. Karl Popper. London: Routledge, 1980. A critical
account of Popper's thought, viewed from the perspective of
contemporary analytic philosophy.
Parusniková, Zuzana & Robert S. Cohen (2009). Rethinking Popper.
Description and contents. Springer.
Radnitzky, Gerard, Bartley, W. W. III eds. Evolutionary Epistemology,
Rationality, and the
Sociology of Knowledge. LaSalle, 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
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.
Rowbottom, Darrell P. Popper's Critical Rationalism: A Philosophical
Investigation. London: Routledge, 2010. A research monograph on
Popper's philosophy of science and epistemology. It critiques and
develops critical rationalism in light of more recent advances in
Schilpp, Paul A., ed. The Philosophy of Karl Popper. Description and
contents. Chicago, IL: Open Court Press, 1974. One of the better
contributions to the
Library of Living Philosophers series. Contains
Popper's intellectual autobiography (v. I, pp. 2–184, also as a
1976 book), a comprehensive range of critical essays, and Popper's
responses to them. ISBN 0-87548-141-8 (vol.I).
ISBN 0-87548-142-6 (Vol II)
Schroeder-Heister, P. "Popper, Karl Raimund (1902–94),"
International Encyclopedia of the Social & Behavioral Sciences,
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.
Shearmur, Jeremy (2008). "
Karl Popper (1902–1994)". In Hamowy,
Ronald. The Encyclopedia of Libertarianism. Thousand Oaks, CA: SAGE;
Cato Institute. pp. 380–81. doi:10.4135/9781412965811.n234.
ISBN 978-1-4129-6580-4. LCCN 2008009151.
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
Stove, D.C., Popper and After: Four Modern Irrationalists. Oxford:
Pergamon. 1982. A vigorous attack, especially on Popper's restricting
himself to deductive logic.
Tausch, Arno. Towards New Maps of Global Human Values, Based on World
Values Survey (6) Data (March 31, 2015). Available at SSRN:
Thornton, Stephen. "Karl Popper," Stanford Encyclopedia of Philosophy,
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".
Zippelius, Reinhold, Die experimentierende Methode im Recht, Akademie
der Wissenschaften Mainz. – Stuttgart: Franz Steiner, 1991,
Wikimedia Commons has media related to Karl Popper.
Wikiquote has quotations related to: Karl Popper
Karl Popper on Stanford Encyclopedia of Philosophy
Karl Popper and Critical Rationalism". Internet Encyclopedia of
"Karl Popper: Political Philosophy". Internet Encyclopedia of
Popper, K. R. "Natural Selection and the Emergence of Mind", 1977.
Karl Popper Web
Influence on Friesian Philosophy
Sir Karl R. Popper in Prague, May 1994
Synopsis and background of The poverty of historicism
"A Skeptical Look at Karl Popper" by Martin Gardner
"A Sceptical Look at 'A Skeptical Look at Karl Popper'" by J C Lester.
Singer, Peter (2 May 1974), "Discovering Karl Popper", The New York
Review of Books, 21 (7), retrieved 21 January 2016
Karl Popper by John N. Gray
Karl Popper on Information Philosopher
History of Twentieth-Century Philosophy of Science, BOOK V: Karl
Popper Site offers free downloads by chapter available for public use.
Karl Popper at Liberal-international.org
A science and technology hypotheses database following Karl Popper's
Karl Popper at Goodreads
Growth of knowledge
Popper's three worlds
Logic of Scientific Discovery (1934)
The Poverty of
The Open Society and Its Enemies
The Open Society and Its Enemies (1945)
Conjectures and Refutations
Conjectures and Refutations (1963)
Links to related articles
J. L. Austin
A. J. Ayer
G. E. M. Anscombe
C. D. Broad
James F. Conant
Bas van Fraassen
R. M. Hare
Carl Gustav Hempel
Peter van Inwagen
J. L. Mackie
G. E. Moore
W. V. O. Quine
Descriptivist theory of names
Ordinary language philosophy
Pragmatic theory of truth
Causal / Deductive / epistemic closure
Denotation / reference
Natural kind / projectability
Paradox of analysis
Ordinary language philosophy
Philosophy of language
Philosophy of science
Philosophy of mind
Concept and object
Hard problem of consciousness
Language of thought
Problem of other minds
Philosophy of artificial intelligence / information /
perception / self
Philosophy of science
A priori and a posteriori
Ignoramus et ignorabimus
Problem of induction
Unity of science
Positivism / Reductionism / Determinism
Rationalism / Empiricism
Received view / Semantic view of theories
Scientific realism / Anti-realism
thermal and statistical
Space and time
Criticism of science
Faith and rationality
History and philosophy of science
History of science
History of evolutionary thought
Relationship between religion and science
Rhetoric of science
Sociology of scientific knowledge
Sociology of scientific ignorance
Philosophers of science by era
William of Ockham
Hugh of Saint Victor
John Stuart Mill
Charles Sanders Peirce
Alfred North Whitehead
C. D. Broad
Carl Gustav Hempel
W. V. O. Quine
Bas van Fraassen
Social and political philosophy
Feminist political theory
Mandate of Heaven
Philosophy and economics
Philosophy of education
Philosophy of history
Philosophy of love
Philosophy of sex
Philosophy of social science
Contributions to liberal theory
History of liberalism
Civil and political rights
Freedom of the press
Freedom of religion
Freedom of speech
Natural and legal rights
Rule of law
Separation of church and state
Juan Bautista Alberdi
Jean le Rond d'Alembert
Simone de Beauvoir
Ludwig Joseph Brentano
Marquis de Condorcet
Ralph Waldo Emerson
John Kenneth Galbraith
William Lloyd Garrison
José Ortega y Gasset
David Lloyd George
Francisco Luís Gomes
Thomas Hill Green
John A. Hobson
Wilhelm von Humboldt
John Maynard Keynes
Salvador de Madariaga
John Stuart Mill
Ludwig von Mises
Donald Barkly Molteno
Leo Chiozza Money
Charles de Montesquieu
José María Luis Mora
Ahmed Lutfi el-Sayed
Hernando de Soto
Anne Louise Germaine de Staël
William Graham Sumner
R. H. Tawney
Johan Rudolph Thorbecke
Henry David Thoreau
Alexis de Tocqueville
Antoine Destutt de Tracy
Anne Robert Jacques Turgot
Lester Frank Ward
Latin America and the Caribbean
Africa Liberal Network (ALN)
Alliance of Liberals and Democrats for Europe
Alliance of Liberals and Democrats for Europe (ALDE)
Alliance of Liberals and Democrats for Europe
Alliance of Liberals and Democrats for Europe Party (ALDEP)
Arab Liberal Federation
Council of Asian Liberals and Democrats (CALD)
European Democratic Party (EDP)
European Liberal Youth
European Liberal Youth (LYMEC)
International Federation of Liberal Youth
International Federation of Liberal Youth (IFLRY)
Liberal Network for Latin America
Liberal Network for Latin America (Relial)
Liberal South East European Network (LIBSEEN)
Liberal bias in academia
Logical positivism / analytic philosophy
Machian positivism (empiriocriticism)
Rankean historical positivism
Russian positivism (empiriomonism)
Critique of metaphysics
Unity of science
Problem of induction
Related paradigm shifts
in the history of science
Non-Euclidean geometry (1830s)
Heisenberg uncertainty principle (1927)
Criticism of science
Holism in anthropology
Naturalism in literature
Objectivity in science
Philosophy of science
Relationship between religion and science
Social science (Philosophy)
1980s Fourth Great Debate in international relations
1990s Science Wars
1830 The Course in Positive Philosophy
1848 A General View of Positivism
1869 Critical History of Philosophy
Idealism and Positivism
Analysis of Sensations
Logic of Modern Physics
1936 Language, Truth, and Logic
1959 The Two Cultures
2001 The Universe in a Nutshell
A. J. Ayer
Materialism and Empirio-criticism
1923 History and Class Consciousness
Logic of Scientific Discovery
1936 The Poverty of Historicism
1942 World Hypotheses
1951 Two Dogmas of Empiricism
Truth and Method
1962 The Structure of Scientific Revolutions
1963 Conjectures and Refutations
1964 One-Dimensional Man
Knowledge and Human Interests
1978 The Poverty of Theory
1980 The Scientific Image
1986 The Rhetoric of Economics
Theodor W. Adorno
Willard Van Orman Quine
Concepts in contention
Recipients of the Sonning Prize
Winston Churchill (1950)
Albert Schweitzer (1959)
Bertrand Russell (1960)
Niels Bohr (1961)
Alvar Aalto (1962)
Karl Barth (1963)
Dominique Pire (1964)
Richard von Coudenhove-Kalergi
Richard von Coudenhove-Kalergi (1965)
Laurence Olivier (1966)
Willem Visser 't Hooft
Willem Visser 't Hooft (1967)
Arthur Koestler (1968)
Halldór Laxness (1969)
Max Tau (1970)
Danilo Dolci (1971)
Karl Popper (1973)
Hannah Arendt (1975)
Arne Næss (1977)
Hermann Gmeiner (1979)
Dario Fo (1981)
Simone de Beauvoir
Simone de Beauvoir (1983)
William Heinesen (1985)
Jürgen Habermas (1987)
Ingmar Bergman (1989)
Václav Havel (1991)
Krzysztof Kieślowski (1994)
Günter Grass (1996)
Jørn Utzon (1998)
Eugenio Barba (2000)
Mary Robinson (2002)
Mona Hatoum (2004)
Ágnes Heller (2006)
Renzo Piano (2008)
Hans Magnus Enzensberger
Hans Magnus Enzensberger (2010)
Orhan Pamuk (2012)
Michael Haneke (2014)
ISNI: 0000 0001 2142 8792
BNF: cb11920314s (data)