Verificationism, also known as the verification idea or the
verifiability criterion of meaning, is the philosophical doctrine that
only statements that are empirically verifiable (i.e. verifiable
through the senses) are cognitively meaningful, or else they are
truths of logic (tautologies).
Verificationism thus rejects as cognitively "meaningless" statements
specific to entire fields such as metaphysics, spirituality, theology,
ethics and aesthetics. Such statements may be meaningful in
influencing emotions or behavior, but not in terms of truth value,
information or factual content.
Verificationism was a central
thesis of logical positivism, a movement in analytic philosophy that
emerged in the 1920s by the efforts of a group of philosophers who
sought to unify philosophy and science under a common naturalistic
theory of knowledge.
5 See also
Although verificationist principles of a general sort—grounding
scientific theory in some verifiable experience—are found
retrospectively even with the American pragmatist C.S. Peirce and with
the French conventionalist Pierre Duhem who fostered
instrumentalism, the vigorous program termed verificationism was
launched by the logical positivists who, emerging from Berlin Circle
Vienna Circle in the 1920s, sought epistemology whereby
philosophical discourse would be, in their perception, as
authoritative and meaningful as empirical science.
Logical positivists garnered the verifiability criterion of cognitive
meaningfulness from young Ludwig Wittgenstein's philosophy of language
posed in his 1921 book Tractatus, and, led by Bertrand Russell,
sought to reformulate the analytic–synthetic distinction in a way
that would reduce mathematics and logic to semantical conventions.
This would be pivotal to verificationism, in that logic and
mathematics would otherwise be classified as synthetic a priori
knowledge and defined as "meaningless" under verificationism.
Seeking grounding in such empiricism as of David Hume, Auguste
Comte, and Ernst Mach—along with the positivism of the latter
two—they borrowed some perspectives from Immanuel Kant, and found
the exemplar of science to be Albert Einstein's general theory of
Logical positivists within the
Vienna Circle quickly recognized that
the verifiability criterion was too stringent. Notably, all universal
generalizations are empirically unverifiable, such that, under
verificationism, vast domains of science and reason, such as
scientific hypothesis, would be rendered meaningless.
Rudolf Carnap, Otto Neurath, Hans Hahn and
Philipp Frank led a faction
seeking to make the verifiability criterion more inclusive, beginning
a movement they referred to as the "liberalization of empiricism".
Moritz Schlick and
Friedrich Waismann led a "conservative wing" that
maintained a strict verificationism. Whereas Schlick sought to reduce
universal generalizations to frameworks of 'rules' from which
verifiable statements can be derived, Hahn argued that the
verifiability criterion should accede to less-than-conclusive
verifiability. Among other ideas espoused by the liberalization
movement were physicalism, over Mach's phenomenalism, coherentism over
foundationalism, as well as pragmatism and fallibilism.
In 1936, Carnap sought a switch from verification to confirmation.
Carnap's confirmability criterion (confirmationism) would not require
conclusive verification (thus accommodating for universal
generalizations) but allow for partial testability to establish
"degrees of confirmation" on a probabilistic basis. Carnap never
succeeded in formalizing his thesis despite employing abundant logical
and mathematical tools for this purpose. In all of Carnap's
formulations, a universal law's degree of confirmation is zero.
That same year saw the publication of A. J. Ayer's work, Language,
Truth and Logic, in which he proposed two types of verification:
strong and weak. This system espoused conclusive verification, yet
accommodated for probabilistic inclusion where verifiability is
inconclusive. Ayer also distinguished between practical and
theoretical verifiability. Under the latter, propositions that cannot
be verified in practice would still be meaningful if they can be
verified in principle.
The Logic of Scientific Discovery
The Logic of Scientific Discovery proposed
falsificationism as a criterion under which scientific hypothesis
would be tenable.
Falsificationism would allow hypotheses expressed as
universal generalizations, such as "all swans are white", to be
provisionally true until falsified by evidence, in contrast to
verificationism under which they would be disqualified immediately as
Though widely recognized as a revision of verificationism,
Popper intended falsificationism as a methodological standard specific
to the sciences rather than as a theory of meaning. Popper regarded
scientific hypotheses to be unverifiable, as well as not "confirmable"
under Carnap's thesis. He also found unscientific,
metaphysical, ethical, and aesthetic statements often rich in meaning
and important in the origination of scientific theories.
The 1951 article "Two Dogmas of Empiricism", by Willard Van Orman
Quine, attacked the analytic/synthetic division and apparently
rendered the verificationist program untenable. Carl Hempel, one of
verificationism's greatest internal critics, had recently concluded
the same as to the verifiability criterion. In 1958, Norwood
Hanson explained that even direct observations must be collected,
sorted, and reported with guidance and constraint by theory, which
sets a horizon of expectation and interpretation, how observational
reports, never neutral, are laden with theory.
The principle was also recognized as being self-refuting: it cannot
itself be empirically verified, and it is not a logical tautology, so
must be meaningless under its own terms.
Thomas Kuhn's landmark book of 1962, The Structure of Scientific
Revolutions—which identified paradigms of science overturned by
revolutionary science within fundamental physics—critically
destabilized confidence in scientific foundationalism, commonly if
erroneously attributed to verificationism. Popper, who had long
claimed to have killed verificationism but recognized that some would
confuse his falsificationism for more of it, was knighted in 1965.
At 1967, John Passmore, a leading historian of 20th-century
philosophy, wrote, "
Logical positivism is dead, or as dead as a
philosophical movement ever becomes"—a general view among
philosophers. Logical positivism's fall heralded postpositivism,
where Popper's view of human knowledge as hypothetical, continually
growing, and open to change ascended, and verificationism became
Karl Popper has been the only philosopher of science often praised by
scientists, whereas verificationists have been likened to
economists of the 19th century who took circuitous, protracted
measures to refuse falsification, that is, refutation, of their
preconceived principles. Still, logical positivists practiced
Popper's principles—conjecturing and refuting—until they ran their
course, catapulting Popper, initially a contentious misfit, to carry
the richest philosophy out of interwar Vienna. And his
falsificationism, as did verificationism, poses a criterion,
falsifiability, to ensure that empiricism anchors scientific
In a 1979 interview, A J Ayer, who had introduced logical positivism
English-speaking world in the 1930s, was asked what he saw as
its main defects, and answered that "nearly all of it was false".
Still, he soon admitted still holding "the same general approach".
The "general approach" of empiricism and reductionism—whereby mental
phenomena resolve to the material or physical, and philosophical
questions largely resolve to ones of language and meaning—has run
through Western philosophy since the 17th century and lived beyond
logical positivism's fall.
In 1977, Ayer had noted, "The verification principle is seldom
mentioned and when it is mentioned it is usually scorned; it
continues, however, to be put to work. The attitude of many
philosophers reminds me of the relationship between Pip and Magwitch
in Dickens's Great Expectations. They have lived on the money, but are
ashamed to acknowledge its source". In the late 20th and early 21st
centuries, the general concept of verification criteria—in forms
that differed from those of the logical positivists—was defended by
Bas van Fraassen, Michael Dummett, Crispin Wright, Christopher
Peacocke, David Wiggins, Richard Rorty, and others.
Epistemic theories of truth
^ Editors of Encyclopædia Britannica, "Verifiability principle",
Encyclopædia Britannica, Website accessed 12 Mar 2014.
^ a b c d e C J Misak, Verificationism: Its History and Prospects (New
York: Routledge, 1995), p viii.
^ Miran Epstein, ch 2 "Introduction to philosophy of science", in
Clive Seale, ed, Researching Society and Culture, 3rd edn (London:
Sage Publications, 2012), pp 18–19.
^ a b c d e Karl Popper, ch 4, subch "Science: Conjectures and
refutations", in Andrew Bailey, ed, First Philosophy: Fundamental
Problems and Readings in Philosophy, 2nd edn (Peterborough Ontario:
Broadview Press, 2011), pp 338–42.
^ Despite Hume's radical empiricism, set forth near 1740, Hume was
also committed to common sense, and apparently did not take his own
skepticism, such as the problem of induction, as drastically as others
later did [Antony G Flew, A Dictionary of Philosophy, rev 2nd edn (New
York: St Martin's Press, 1984), "Hume", p 156].
^ a b c Sahotra Sarkar and Jessica Pfeifer, eds, The
Science: An Encyclopedia, Volume 1: A–M (New York: Routledge, 2006),
"Rudolf Carnap", p 83.
^ Moritz Schlick, 1931, "Die Kausalität in der gegenwärtigen
Physik", Die Naturwissen-schaften, 19: 145–162; transl. "Causality
in Contemporary Physics" in Schlick 1979b, pp. 176–209
^ Hahn, Hans, 1933, Logik, Mathematik und Naturerkennen, Wien: Gerold,
transl. "Logic, Mathematics, and
Knowledge of Nature", in B. McGuiness
1987, pp. 24–45.
^ Antony G Flew, A Dictionary of Philosophy, rev 2nd edn (New York: St
Martin's Press, 1984), "Neurath", p 245.
^ Mauro Murzi "
Rudolf Carnap (1891–1970)", Internet Encyclopedia of
Philosophy, 12 Apr 2001.
^ a b c d Malachi Haim Hacohen, Karl Popper: The Formative Years,
1902–1945: Politics and
Interwar Vienna (Cambridge:
Cambridge University Press, 2000), pp 212–13.
^ a b Peter Godfrey-Smith, Theory and Reality: An Introduction to the
Philosophy of Science (Chicago: University of Chicago Press, 2005), p
Falsificationism is simply Popper's scientific epistemology, whereas
critical rationalism is Popper's general epistemology.
^ James Fetzer, "Carl Hempel", in Edward N Zalta, ed, The Stanford
Philosophy (Spring 2013): "However surprising it may
initially seem, contemporary developments in the philosophy of science
can only be properly appreciated in relation to the historical
background of logical positivism. Hempel himself attained a certain
degree of prominence as a critic of this movement. Language,
Logic (1936; 2nd edition, 1946), authored by A J Ayer, offers a lucid
exposition of the movement, which was—with certain
variations—based upon the analytic/synthetic distinction, the
observational/theoretical distinction, and the verifiability criterion
Hempel (1950, 1951), meanwhile, demonstrated that the verifiability
criterion could not be sustained. Since it restricts empirical
knowledge to observation sentences and their deductive consequences,
scientific theories are reduced to logical constructions from
observables. In a series of studies about cognitive significance and
empirical testability, he demonstrated that the verifiability
criterion implies that existential generalizations are meaningful, but
that universal generalizations are not, even though they include
general laws, the principal objects of scientific discovery.
Hypotheses about relative frequencies in finite sequences are
meaningful, but hypotheses concerning limits in infinite sequences are
not. The verifiability criterion thus imposed a standard that was too
strong to accommodate the characteristic claims of science and was not
^ Bruce Caldwell, Beyond Positivism: Economic Methodology in the 20th
Century, rev edn (London: Routledge, 1994), p 47–48.
^ Samir Okasha,
Philosophy of Science: A Very Short Introduction (New
York: Oxford University Press, 2002) ch 5.
^ "But for a brief lapse around 1929/30, then, the post-Aufbau Carnap
fully represents the position of
Vienna Circle anti-foundationalism.
In this he joined Neurath whose long-standing anti-foundationalism is
evident from his famous simile likening scientists to sailors who have
to repair their boat without ever being able to pull into dry dock
(1932b). Their positions contrasted at least prima facie with that of
Schlick (1934) who explicitly defended the idea of foundations in the
Circle's protocol-sentence debate. Even Schlick conceded, however,
that all scientific statements were fallible ones, so his position on
foundationalism was by no means the traditional one. The point of his
'foundations' remained less than wholly clear and different
interpretation of it have been put forward. ... While all in the
Circle thus recognized as futile the attempt to restore certainty to
scientific knowledge claims, not all members embraced positions that
rejected foundationalism tout court. Clearly, however, attributing
foundationalist ambitions to the Circle as a whole constitutes a total
misunderstanding of its internal dynamics and historical development,
if it does not bespeak wilfull ignorance. At most, a foundationalist
faction around Schlick can be distinguished from the so-called left
wing whose members pioneered anti-foundationalism with regard to both
the empirical and formal sciences" Thomas Uebel, "Vienna Circle", sec
Reductionism and foundationalism: Two criticisms partly
rebutted", in Edward N Zalta, ed, The Stanford Encyclopedia of
Philosophy (Summer 2012 edn)].
^ a b c d Oswald Hanfling, ch 5 "Logical positivism", in Stuart G
Philosophy of Science, Logic and Mathematics in the Twentieth
Century (London: Routledge, 1996), pp 193–94.
^ Mark Blaug The Methodology of Economics: Or, How Economists Explain,
2nd edn (Cambridge UK: Cambridge University Press, 1992), ch 3 "The
verificationists, a largely nineteenth-century story", p 51.
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
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
1879 Idealism and Positivism
Analysis of Sensations
1927 The Logic of Modern Physics
1936 Language, Truth, and Logic
1959 The Two Cultures
2001 The Universe in a Nutshell
A. J. Ayer
1909 Materialism and Empirio-criticism
1923 History and Class Consciousness
1934 The 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