Verificationism rejects statements of metaphysics, theology, ethics and aesthetics as meaningless in conveying truth value or factual content, though they may be meaningful in influencing emotions or behavior.
[5] Verificationism, as principle, would be conceived in the 1920s by the logical positivists of the Vienna Circle, who sought an epistemology whereby philosophical discourse would be, in their perception, as authoritative and meaningful as empirical science.
[6] The movement established grounding in the empiricism of David Hume,[7] Auguste Comte and Ernst Mach, and the positivism of the latter two, borrowing perspectives from Immanuel Kant and defining their exemplar of science in Einstein's general theory of relativity.
Specifically, universal generalizations were noted to be empirically unverifiable, rendering vital domains of science and reason, including scientific hypothesis, meaningless under verificationism, absent revisions to its criterion of meaning.
[11] 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".
[9] 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.
[18] Logical positivists too adopted the criterion, even as their movement ran its course, catapulting Popper, initially a contentious misfit, to carry the richest philosophy out of interwar Vienna.
[4] Logical positivism's fall heralded postpositivism, where Popper's view of human knowledge as hypothetical, continually growing and open to change ascended[24] and verificationism, in academic circles, became mostly maligned.
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.