Verificationism

Verificationism, also known as the verification principle or the verifiability criterion of meaning, is the philosophical doctrine which asserts that a statement is meaningful only if it is either empirically verifiable (confirmed through the senses) or a truth of logic (tautologies). Verificationism rejects statements of metaphysics, theology, ethics and aesthetics as cognitively meaningless. Such statements may be meaningful in influencing emotions or behavior, but not in terms of conveying 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 philosophers who sought to unify philosophy and science under a common naturalistic theory of knowledge. The verifiability criterion underwent various revisions throughout the 1920s to 1950s. However, by the 1960s, it was deemed to be irreparably untenable. Its abandonment would eventually precipitate the collapse of the broader logical positivist movement.

Origins

Although earlier philosophical principles which aim to ground scientific theory in some verifiable experience are found within the work of American pragmatist C.S. Peirce and that of French conventionalist Pierre Duhem, who fostered instrumentalism, the project of verificationism was launched by the logical positivists who, emerging from the Berlin Circle and the Vienna Circle in the 1920s, sought an 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 Ludwig Wittgenstein's philosophy of language posed in his 1921 book Tractatus and, led by Gottlob Frege, sought to reformulate the analytic–synthetic distinction in a way that would reduce mathematics and logic to semantical conventions. This would serve as a vital foundation for the project, without which logic and mathematics would be classified as synthetic a priori knowledge and rendered meaningless under verificationism.

They sought grounding for their philosophy in the empiricism of David Hume, Auguste Comte and Ernst Mach—along with the positivism of the latter two—borrowing perspectives from Immanuel Kant and an exemplar of science in Einstein's general theory of relativity.

Revisions

Logical positivists within the Vienna Circle recognized quickly that the verifiability criterion was too stringent. Notably, universal generalizations—critical to scientific hypothesis—were noted to be empirically unverifiable. It would follow that vital domains of science of reason would be definable as meaningless under verificationism without revisions to its criterion of meaning.

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 accommodate less-than-conclusive verifiability. The liberalization movement would espouse physicalism over Mach's phenomenalism, coherentism over foundationalism, as well as pragmatism and fallibilism, among other ideas.

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 was zero.

In Language, Truth and Logic, published that year, A. J. Ayer distinguished between strong and weak verification. This system espoused conclusive verification, yet accommodated for probabilistic inclusion where verifiability is inconclusive. He also distinguished theoretical from practical verifiability, proposing that statements that are verifiable in principle should be meaningful, even if unverifiable in practice.

Criticisms

Philosopher Karl Popper, a graduate of the University of Vienna, though not a member within the ranks of the Vienna Circle, was among the foremost critics of verificationism. He identified three fundamental deficiencies in verifiability as a criterion of meaning:

• Verificationism rejects universal generalizations, like "all swans are white," as meaningless. Popper argues that while universal statements cannot be verified, they can be proven false, a foundation on which he was to propose his criterion of falsifiability.
• Verificationism allows existential statements, like “unicorns exist”, to be classified as scientifically meaningful, despite the fact that there is no way of definitively showing that they are false and one could possibly find one somewhere not yet examined.
• Verificationism is meaningless by virtue of its own criterion because it cannot be empirically verified. Thus the concept is self-defeating.

Popper regarded scientific hypotheses to never be completely verifiable, and not confirmable under Carnap's thesis. He also considered some metaphysical, ethical and aesthetic statements to be rich in meaning and important in the origination of scientific theories.

Other philosophers also voiced their own criticisms of verificationism:

• The 1951 article "Two Dogmas of Empiricism", by Willard Van Orman Quine, found no suitable explanations for the concept of analyticity in that they reduced ultimately to circular reasoning. This served to uproot the analytic/synthetic division pivotal to verificationism.
• Carl Hempel (1950, 1951) demonstrated that the verifiability criterion was not justifiable in that it was too strong to accommodate key proceedings within science, such as general laws and limits in infinite sequences.
• In 1958, Norwood Hanson explained that direct observations are never truly neutral in that they are laden with theory. ie. Influenced by a system of presuppositions that act as an interpretative framework for those observations. Those subscribed to different theories might thus report radically different observations, even when they observe the same phenomena.
• Thomas Kuhn's landmark book of 1962, The Structure of Scientific Revolutions—which discussed paradigm shifts in fundamental physics—critically undermined confidence in scientific foundationalism, a theory commonly, if erroneously, attributed to verificationism.

Falsifiability

Main article: Falsifiability

In The Logic of Scientific Discovery (1959), Popper proposed falsifiability, or falsificationism. Though formulated in the context of what he perceived were intractable problems in both verifiability and confirmability, Popper intended falsifiability, not as a criterion of meaning like verificationism (as commonly misunderstood), but as a criterion to demarcate scientific statements from non-scientific statements.

Notably, the falsifiability criterion would allow for scientific hypotheses (expressed as universal generalizations) to be held as provisionally true until proven false by observation, whereas under verificationism, they would be disqualified immediately as meaningless.

In formulating his criterion, Popper was informed by the contrasting methodologies of Albert Einstein and Sigmund Freud. He noted that Einstein developed predictions about future instances based upon the past and, in conducting observations, sought evidence that would disprove his theories. Freud, in contrast, presented hypotheses to explain the past, rather than the future, and sought data that could be conformed to his theories. For Popper, this clarified a key distinction between science and pseudoscience.

Though falsificationism has been criticized extensively by philosophers for methodological shortcomings in its intended demarcation of science, Popper has been the only philosopher of science praised by many scientists. Despite its problems, his criterion of falsifiability was to ensure that scientific theory was henceforth to be anchored in empiricism and logical positivists would also adopt the criterion, catapulting Popper, initially a contentious misfit, to carry the richest philosophy out of interwar Vienna.

Legacy

In 1967, John Passmore, a leading historian of 20th-century philosophy, wrote, "Logical positivism is dead, or as dead as a philosophical movement ever becomes". Logical positivism's fall heralded postpositivism, where Popper's view of human knowledge as hypothetical, continually growing and open to change ascended and verificationism, in academic circles, became mostly maligned.

In a 1976 TV interview, A. J. Ayer, who had introduced logical positivism to the English-speaking world in the 1930s was asked what he saw as its main defects, and answered that "nearly all of it was false". However, he soon said that he still held "the same general approach", referring to empiricism and reductionism, whereby mental phenomena resolve to the material or physical and philosophical questions largely resolve to ones of language and meaning. In 1977, Ayer recognized that the verification principle was not widely accepted but acknowledged that it still held relevance and was being utilised. "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.

See also

• Epistemic theories of truth
• Newton's flaming laser sword
• Semantic anti-realism (epistemology)