Logical positivism, also referred to as logical empiricism or neo-positivism, constituted a philosophical movement rooted in the empiricist tradition. Its primary objective was to establish a scientific philosophy where philosophical discourse could attain a level of authority and significance comparable to that of empirical science, as perceived by its advocates.
Logical positivism, also known as logical empiricism or neo-positivism, was a philosophical movement, in the empiricist tradition, that sought to formulate a scientific philosophy in which philosophical discourse would be, in the perception of its proponents, as authoritative and meaningful as empirical science.
The core tenet of logical positivism was the verification principle, also termed the "verifiability criterion of meaning." This principle asserted that a statement possesses cognitive meaning exclusively if it is empirically verifiable or if it represents a tautology (i.e., true by definition or logical structure). Consequently, this criterion dismissed metaphysical, theological, ethical, and aesthetic statements as cognitively meaningless, lacking truth value or factual content. Although the movement aimed to reformulate philosophy by emulating the methodology of empirical science, it was mistakenly characterized as an effort to impose stringent regulations and standards on the scientific process.
Originating in the late 1920s, the movement coalesced around philosophers, scientists, and mathematicians associated with the Vienna Circle and Berlin Circle, subsequently thriving across various European intellectual hubs throughout the 1930s. Following World War II, numerous adherents relocated to English-speaking countries, leading to a reorientation of the project towards more moderate objectives within the philosophy of science.
By the 1950s, fundamental issues inherent in logical positivism's core principles were increasingly perceived as insurmountable. This led to mounting criticism from prominent philosophers, including Willard Van Orman Quine and Karl Popper, and even from within the movement itself, notably from Carl Hempel. These unresolved challenges ultimately contributed to the movement's decline and subsequent abandonment by the 1960s. In 1967, philosopher John Passmore famously declared logical positivism "dead, or as dead as a philosophical movement ever becomes."
Origins
The emergence of logical positivism in Germany and Austria occurred within a cultural milieu marked by the pervasive influence of Hegelian metaphysics and the contributions of its successors, such as F. H. Bradley, whose metaphysical frameworks depicted reality independently of empirical observation. Concurrently, the late 19th century witnessed the rise of neo-Kantianism, a philosophical current rooted in the rationalist tradition.
The theoretical underpinnings of the logical positivist program were established through the empiricist philosophies of David Hume, Auguste Comte, and Ernst Mach, alongside the positivist tenets of Comte and Mach. The movement identified Einstein's general theory of relativity as its scientific paradigm. Adhering to Mach's phenomenalism, which posits that material objects exist solely as sensory stimuli rather than as independently observable entities, logical positivists considered all scientific knowledge to be derived exclusively from sensory experience. Additional influences included Percy Bridgman's operationalism, which asserts that a concept is only knowable if it can be experimentally measured, and Immanuel Kant's insights into aprioricity.
Ludwig Wittgenstein's seminal work, Tractatus Logico-Philosophicus, laid the theoretical groundwork for the verifiability principle. This text advanced a conception of philosophy as a "critique of language," delineating theoretical distinctions between meaningful and meaningless discourse. The Tractatus espoused a correspondence theory of truth, contrasting with a coherence theory. While logical positivists were also shaped by Wittgenstein's approach to probability, some, as noted by Neurath, expressed reservations regarding the metaphysical aspects present in the Tractatus.
History
The Vienna and Berlin Circles
The Vienna Circle, primarily led by Moritz Schlick, convened around the University of Vienna and at the Café Central. Its philosophical stances were articulated in a 1929 manifesto authored by Otto Neurath, Hans Hahn, and Rudolf Carnap. Schlick, initially a proponent of neo-Kantianism, subsequently shifted his views, influenced by Carnap's 1928 publication, Der logische Aufbau der Welt (The Logical Structure of the World). The members of the Vienna Circle fostered strong collaborative relationships with the Berlin Circle, where Hans Reichenbach held a prominent position. Carl Hempel, who studied under Reichenbach in Germany, also became a significant figure in the movement's later development. Karl Popper, whom Neurath famously dubbed the "Official Opposition," served as a cordial yet persistent critic of the movement.
Initially, key figures such as Carnap, Hahn, and Neurath acknowledged the excessive stringency of the verifiability criterion, noting its rejection of universal statements essential for scientific hypotheses. A radical left wing, spearheaded by Neurath and Carnap within the Vienna Circle, advocated for modifications to relax this criterion, an initiative they termed the "liberalisation of empiricism." Conversely, a conservative right wing, under the leadership of Schlick and Waismann, aimed to categorize universal statements as analytic truths, thereby aligning them with the established criterion. Carnap, a proponent of the liberal faction, underscored the importance of fallibilism and pragmatics, viewing both as fundamental to empiricism. Neurath advocated for a transition from Mach's phenomenalism to physicalism, a stance that Schlick subsequently opposed. The divergence within the Vienna Circle also mirrored political disparities, particularly as Neurath and Carnap endeavored to orient scientific inquiry towards social reform.
Both Schlick and Carnap were influenced by, and subsequently endeavored to delineate, logical positivism in contrast to Ernst Cassirer's neo-Kantianism, a prominent contemporary figure of the Marburg school, and Edmund Husserl's phenomenology. Logical positivists particularly challenged Martin Heidegger's abstruse metaphysics, which they considered emblematic of the concepts their epistemological doctrines repudiated. During the early 1930s, Carnap engaged in a notable debate with Heidegger concerning "metaphysical pseudosentences."
The Anglosphere
Moritz Schlick, serving as the movement's initial envoy to the New World, visited Stanford University in 1929; however, he primarily resided in Vienna and was tragically murdered at the university in 1936 by a former student, Johann Nelböck, who was reportedly mentally unstable. In the same year, A. J. Ayer, a British participant in several Vienna Circle meetings since 1933, published Language, Truth and Logic, thereby introducing logical positivism to the English-speaking intellectual sphere. The ascent of the Nazi Party to power in Germany in 1933 initiated an exodus of intellectuals, a phenomenon that intensified following Germany's annexation of Austria in 1938. Many logical positivists, a significant number of whom were Jewish, faced persecution and continued to flee throughout the pre-war era. Consequently, their philosophical tenets gained prominence within the Anglosphere.
By the close of the 1930s, numerous adherents of the movement had adopted Neurath's physicalism, which posits that material objects are not merely reducible to sensory stimuli but rather exist as publicly observable entities within the objective world, replacing phenomenalism. Neurath subsequently established residence in England, where he passed away in 1945. Carnap, Reichenbach, and Hempel ultimately settled permanently in America.
The Post-War Period
Subsequent to the Second World War, logical positivism—also known by some as logical empiricism—shifted its focus toward less radical aims within the philosophy of science. Under the leadership of Carl Hempel, who articulated the covering law model of scientific explanation, the movement evolved into a foundational element of analytic philosophy in the Anglosphere, with its impact reaching beyond philosophy into the social sciences. Concurrently, the movement's core tenets and doctrines faced escalating criticism, notably from Willard Van Orman Quine, Norwood Hanson, Karl Popper, Thomas Kuhn, and Carl Hempel himself.
Core Principles
Verification and Confirmation
The Verifiability Criterion of Meaning
As per the verifiability criterion of meaning, a statement attains cognitive meaningfulness exclusively if it can be empirically verified or if it constitutes an analytic truth (i.e., its truth is inherent in its meaning or logical structure). The concept of cognitive meaningfulness received diverse definitions, including the possession of truth value, correspondence to a potential state of affairs, or intelligibility akin to scientific statements. Other categories of meaning, such as emotive, expressive, or figurative interpretations, were excluded from subsequent consideration.
Metaphysics, theology, and significant portions of ethics and aesthetics were deemed to fall short of this criterion, consequently being classified as cognitively meaningless, possessing only emotive significance. It is noteworthy, however, that Schlick regarded ethical and aesthetic propositions as cognitively meaningful. Ethical and aesthetic assertions were categorized as expressions of subjective preference, while theological and metaphysical discourse comprised "pseudostatements" lacking truth-value. Consequently, logical positivism implicitly affirmed Hume's law, which posits an insurmountable divide between factual and evaluative statements, precluding the justification of the latter by the former. In Language, Truth and Logic (1936), A. J. Ayer articulated an extreme interpretation of this principle, known as the boo/hooray doctrine, which contended that all evaluative judgments constitute nothing more than emotional responses.
Modifications to the Criterion
Logical positivists within the Vienna Circle swiftly recognized that the verifiability criterion was excessively stringent. Specifically, universal propositions were observed to be empirically unverifiable, thereby classifying crucial areas of scientific inquiry and rational thought, including scientific hypotheses, as cognitively meaningless within the framework of verificationism. Such an outcome presented substantial challenges for the logical positivist agenda, necessitating modifications to its criterion of meaning.
In his 1936 and 1937 publications, titled Testability and Meaning, Carnap advanced the concept of confirmation as an alternative to verification, positing that while universal laws are not verifiable, they are amenable to confirmation. Carnap extensively utilized logical and mathematical methodologies to develop an inductive logic capable of quantifying probability based on degrees of confirmation. Nevertheless, he did not succeed in formulating a complete model. Within Carnap's inductive logic, the degree of confirmation for any universal law consistently remained at zero. The subsequent development of what became known as the "criterion of cognitive significance," evolving from this research, spanned three decades (Hempel 1950, Carnap 1956, Carnap 1961). Carl Hempel, who later emerged as a notable critic of the logical positivist movement, further clarified the paradox of confirmation.
In his 1936 work, Language, Truth and Logic, A. J. Ayer differentiated between strong and weak forms of verification. He posited that, "A proposition is said to be verifiable, in the strong sense of the term, if, and only if, its truth could be conclusively established by experience," whereas it is verifiable in the weak sense "if it is possible for experience to render it probable." Ayer further asserted that, "no proposition, other than a tautology, can possibly be anything more than a probable hypothesis." Consequently, he concluded that all propositions are amenable to weak verification.
The Analytic-Synthetic Distinction
Within epistemological theories of justification, a priori statements are those ascertainable independently of empirical observation, in contrast to a posteriori statements, which rely upon observational evidence. Propositions can also be classified as either analytic or synthetic: Analytic statements derive their truth from their intrinsic meaning or logical structure, functioning as tautologies that are necessarily true but provide no new information about the world. Conversely, synthetic statements are contingent propositions that describe factual states of affairs in the world.
David Hume established a clear distinction between analytic and synthetic propositions, classifying all knowledge exclusively into "relations of ideas" (which are a priori, analytic, and abstract) or "matters of fact and real existence" (a posteriori, synthetic, and concrete); this categorization is commonly known as Hume's fork. Immanuel Kant subsequently identified an additional category of knowledge: synthetic a priori statements, which convey information about the world yet are apprehended independently of observation. This concept is central to Kant's transcendental idealism, which posits that the mind actively constructs phenomena, with intuitive truths—such as synthetic a priori notions of space and time—serving as an interpretive framework for an observer's worldly experience. Kant's thesis aimed to resolve Hume's problem of induction concerning Newton's law of universal gravitation by classifying the uniformity of nature as a form of a priori knowledge.
The Vienna Circle dismissed Kant's concept of synthetic a priori knowledge due to its conflict with the verifiability criterion. Nevertheless, they embraced the Kantian stance that mathematics and logic—typically regarded as synthetic truths—are a priori. Carnap addressed this inconsistency by reinterpreting logical truths as tautologies, thereby classifying logic as analytic, a development rooted in the theoretical framework of Wittgenstein's Tractatus. Subsequently, mathematics was to be reduced to logic via the logicist methodology advanced by Gottlob Frege. Essentially, Carnap's reinterpretation of analyticity elaborated upon Hume's fork, thereby reinforcing the analytic-synthetic distinction. This approach was crucial for establishing the compatibility of the verification principle with both mathematics and logic.
Observation-Theory Distinction
Carnap dedicated a significant portion of his career to the fundamental principle of rational reconstruction, which posits that scientific theories can be formalized using predicate logic, with their constituent elements classified as either observation terms or theoretical terms. Observation terms are defined through direct empirical observation and are presumed to possess stable empirical definitions, while theoretical terms denote unobservable entities within a theory, encompassing abstract concepts like mathematical formulas. These two categories of fundamental terms were intended to be semantically linked through a deductive interpretive framework, known as correspondence rules.
Initially, Carnap hypothesized that correspondence rules could establish definitions for theoretical terms based on observation terms, arguing that scientific knowledge could be unified by reducing theoretical laws to "protocol sentences" derived from observable facts. However, he subsequently abandoned this reconstructive model, proposing instead that theoretical terms might be implicitly defined by a theory's axioms. Moreover, he suggested that, in certain instances, observation terms could acquire meaning from theoretical terms through correspondence rules. In this context, 'implicit' definition signifies that the axioms function to preclude interpretations that would falsify the theory. Consequently, axioms indirectly define theoretical terms by narrowing the range of potential interpretations to only those that are veridical.
Carnap's thesis, which reconstructs the semantics of scientific language, draws upon prior work in syntactic reconstruction, specifically referencing Bertrand Russell's logical atomism—the proposition that natural language statements can be transformed into standardized semantic subunits structured by a logical syntax. In the context of later contributions by Carl Hempel, Ernest Nagel, and Herbert Feigl, rational reconstruction is occasionally termed the received view or the syntactic view of theories.
Logicism
Bertrand Russell aimed to translate the mathematical formulations of physics into symbolic logic by reducing mathematics to its logical foundations. Gottlob Frege initiated this logicist program, collaborating with Russell for a period before ultimately disengaging. Russell subsequently advanced the project with Alfred North Whitehead in their seminal work, Principia Mathematica, which influenced mathematically inclined logical positivists like Hans Hahn and Rudolf Carnap.
Carnap's initial anti-metaphysical writings utilized Russell's theory of types. Similar to Russell, Carnap conceived of a universal language capable of reconstructing mathematics and, consequently, encoding physics. However, Kurt Gödel's incompleteness theorem demonstrated the impossibility of this endeavor, except in trivial instances, and Alfred Tarski's undefinability theorem ultimately eroded all aspirations of reducing mathematics to logic. Consequently, the development of a universal language did not materialize from Carnap's 1934 publication, Logische Syntax der Sprache (Logical Syntax of Language). Nevertheless, certain logical positivists, such as Carl Hempel, maintained their advocacy for logicism.
Philosophy of Science
The logical positivist movement significantly reduced its revolutionary fervor after the defeat of Nazism and the decline of competing philosophies advocating radical reform, such as Marburg neo-Kantianism, Husserlian phenomenology, and Heidegger's existential hermeneutics. Operating within the intellectual environment of American pragmatism and common-sense empiricism, its proponents shifted from campaigning to transform traditional philosophy into a radical scientific philosophy to becoming respected contributors within the emerging philosophical subdiscipline of philosophy of science. With Ernest Nagel's backing, their influence was particularly notable in the social sciences.
Scientific Explanation
Carl Hempel played a significant role in formulating the deductive-nomological (DN) model, which was then considered the leading model of scientific explanation, even endorsed by critics of neo-positivism like Popper. The DN model posits that a scientific explanation is valid exclusively if it constitutes a deductive inference from a set of explanatory premises (explanans) to the observation or theory requiring explanation (explanandum). This model mandates that the premises must incorporate at least one law, defined as an unrestricted generalization presented in a conditional form: "If A, then B". Consequently, laws are distinct from mere regularities (e.g., "George always carries only $1 bills in his wallet"), which do not inherently support counterfactual assertions. Moreover, laws are required to be empirically verifiable, adhering to the verification principle.
The DN model disregards causal mechanisms beyond the principle of constant conjunction ("first event A and then always event B"), aligning with the Humean empiricist premise that while event sequences are observable, the underlying causal principles are not. Hempel asserted that precisely formulated natural laws (empirically confirmed regularities) adequately approximate causal explanation.
Subsequently, Hempel introduced a probabilistic model for scientific explanation, known as the inductive-statistical (IS) model. The derivation of statistical laws from other statistical laws was further categorized as the deductive-statistical (DS) model. The DN and IS models are jointly termed the "covering law model" or "subsumption theory," with the latter term reflecting the movement's declared objective of "theory reduction."
Unity of Science
Logical positivists advocated for a unified science that would integrate all scientific disciplines (including specialized sciences like biology, anthropology, sociology, and economics, as well as the fundamental science, or fundamental physics) into a single epistemic framework. Central to this vision was the principle of theory reduction, which proposed using the covering law model to establish connections among the special sciences and subsequently reduce all their laws to those of fundamental physics.
The movement conceptualized a universal scientific language capable of articulating statements with shared meaning, comprehensible across all scientific domains. Carnap aimed to achieve this by systematically reducing the linguistic terminology of more specialized fields to that of more fundamental ones. Several reduction methods were suggested, including the application of set theory to manipulate logically primitive concepts (as demonstrated in Carnap's Logical Structure of the World, 1928) or through analytic and a priori deductive processes (as detailed in Testability and Meaning, 1936, 1937). Numerous publications over three decades endeavored to clarify this concept.
Criticism
In the post-war era, core tenets of logical positivism, including the verifiability criterion, the analytic-synthetic distinction, and the observation-theory distinction, faced increasing scrutiny. By the 1950s, this critique had intensified and diversified, leading to a broad consensus, even among philosophers with divergent epistemological objectives, that the logical positivist agenda was unsustainable. Notable critics included Karl Popper, W. V. O. Quine, Norwood Hanson, Thomas Kuhn, Hilary Putnam, J. L. Austin, Peter Strawson, Nelson Goodman, and Richard Rorty. Notably, Hempel, a prominent figure within the movement, also became a significant critic, rejecting the positivist assertion that empirical knowledge is confined to basic statements, observation statements or protocol statements.
Karl Popper
Karl Popper, an alumnus of the University of Vienna, was a vocal opponent of the logical positivist movement from its earliest stages. In Logik der Forschung (1934, published in English in 1959 as The Logic of Scientific Discovery), he directly challenged verificationism, asserting that the problem of induction precludes the conclusive verification of scientific hypotheses and universal statements. He argued that any such attempt would entail the fallacy of affirming the consequent, as verification inherently fails to exclude alternative valid explanations for a given phenomenon or observation. Popper subsequently maintained that the verifiability criterion's content itself cannot be empirically verified, rendering it meaningless by its own terms and ultimately self-defeating as a foundational principle.
In the same publication, Popper introduced the concept of falsifiability. He posited this not as a criterion for cognitive meaning, unlike verificationism (a common misinterpretation), but rather as a demarcation criterion to differentiate scientific from non-scientific statements, thereby defining the limits of science. Popper noted that while universal statements resist verification, they are susceptible to falsification. He further observed that the most fruitful scientific theories tended to be those with the highest 'predictive risks' of being disproven by empirical observation. Consequently, he concluded that the scientific method ought to operate as a hypothetico-deductive model. Within this framework, scientific hypotheses must meet his falsifiability criterion, be regarded as provisionally true until empirically disproven, and be corroborated by supporting evidence rather than merely verified or confirmed.
By rejecting neo-positivist conceptions of cognitive meaningfulness, Popper affirmed that metaphysics possessed significant meaning and played a crucial role in the genesis of scientific theories. He also deemed value systems indispensable to science's pursuit of truth. Concurrently, he criticized pseudoscience, highlighting the confirmation biases that bolster unfalsifiable conjectures (particularly in fields like psychology and psychoanalysis) and the reliance on ad hoc arguments to preserve predictive theories already definitively disproven.
Willard V. O. Quine
In his influential 1951 paper Two Dogmas of Empiricism, American philosopher and logicist Willard Van Orman Quine critiqued the analytic-synthetic distinction. Quine meticulously analyzed the concept of analyticity, concluding that all efforts to elucidate it invariably devolved into circular reasoning. He therefore inferred that if analyticity proved untenable, then the neo-positivist proposal to redefine its parameters was equally unsustainable. However, Carnap's reinterpretation of analyticity was essential for logic and mathematics to retain meaningfulness within the framework of verificationism. Quine's critique incorporated various objections on this subject that he had previously communicated to Carnap as early as 1933. His seminal work effectively rendered the verifiability criterion indefensible, thereby jeopardizing the entire logical positivist enterprise.
Norwood Hanson
In 1958, Norwood Hanson's seminal work, Patterns of Discovery, introduced and elaborated the concept of theory-ladenness. Hanson, alongside Thomas Kuhn, contended that even ostensibly direct observations are inherently non-neutral, being laden with theory; that is, they are shaped by a framework of theoretical presuppositions that serve as an interpretive lens for sensory input. Consequently, proponents of divergent theories could articulate fundamentally distinct observations even when examining identical phenomena. Hanson's argument directly challenged the conventional observation-theory distinction, which posits a clear demarcation between observational and non-observational (theoretical) language. More broadly, his conclusions fundamentally questioned the core tenets of empiricism by scrutinizing the presumed infallibility and objectivity of empirical observation.
Thomas Kuhn
Thomas Kuhn's influential 1962 publication, The Structure of Scientific Revolutions, which explored paradigm shifts within fundamental physics, significantly eroded confidence in scientific foundationalism. Kuhn posited an alternative coherentist model of science, suggesting that scientific advancement proceeds through established, coherent conceptual frameworks that periodically experience sudden, revolutionary transformations.
While foundationalism was frequently regarded as an integral tenet of logical positivism—and Kuhn's thesis interpreted as an epistemological critique of the movement—such perspectives were oversimplified. During the 1930s, Otto Neurath had advocated for coherentism, famously likening scientific progress to the ongoing reconstruction of a ship at sea. Rudolf Carnap had considered foundationalism between 1929 and 1930, but subsequently, he, Hans Hahn, and others aligned with Neurath in embracing a coherentist philosophical stance. The conservative faction of the Vienna Circle, led by Moritz Schlick, adhered to a version of foundationalism, yet its underlying principles were characterized by unconventional or ambiguous definitions.
In a certain respect, Kuhn's work achieved a unification of science, not through the integration of scientific specializations via epistemological or linguistic frameworks, but rather through historical and sociological analysis. His concepts rapidly gained traction among academics in non-scientific fields, particularly within the social sciences where neo-positivist thought was prevalent, thereby initiating a transition in academia towards postpositivism or postempiricism.
Hilary Putnam
In his 1962 critique of the 'received view,' Hilary Putnam challenged the observation-theory distinction. Putnam asserted that the demarcation between 'observation terms' and 'theoretical terms' was unsustainable, concluding that both classifications possess the capacity to be theory-laden. Consequently, he noted that practical observational reports often incorporate theoretical terminology. He provided examples where observation terms could be applied to entities that Rudolf Carnap would categorize as unobservables. For instance, within Newton's corpuscular theory of light, observational concepts are applicable to both sub-microscopic and macroscopic phenomena.
Putnam championed scientific realism, a philosophical stance asserting that scientific theories accurately depict an objective reality that exists independently of sensory perception. He repudiated positivism, characterizing it as a form of metaphysical idealism, given its exclusion of any potential for acquiring knowledge about the unobservable dimensions of nature. Furthermore, he rejected instrumentalism, which posits that a scientific theory's merit is determined not by its correspondence to reality, but by its efficacy in generating empirical predictions or resolving theoretical dilemmas.
Decline and Legacy
In 1967, John Passmore famously declared, "Logical positivism is dead, or as dead as a philosophical movement ever becomes." This assertion resonated with a pervasive academic consensus that the movement had exhausted its intellectual trajectory by the close of the 1960s. The demise of logical positivism ushered in postpositivism, a paradigm characterized by Karl Popper's critical rationalism—which conceptualized human knowledge as perpetually advancing through a process of conjectures and refutations—and by Thomas Kuhn's historical and sociological insights into the discontinuous, 'saltatory' nature of scientific progress.
During a 1976 interview, A. J. Ayer, credited with introducing logical positivism to the English-speaking philosophical community in the 1930s, acknowledged its primary flaws, stating that "nearly all of it was false." Nevertheless, Ayer asserted that the movement remained "true in spirit," emphasizing its foundational tenets of empiricism and reductionism. These principles posited that mental phenomena could be resolved into material or physical components, and that philosophical inquiries largely reduced to matters of language and semantic interpretation. Despite its inherent challenges, logical positivism played a crucial role in establishing analytic philosophy within the English-speaking world, exerting influence beyond philosophy to impact the development of psychology and the social sciences. Post-war, Carl Hempel's significant contributions were instrumental in solidifying the philosophy of science as a distinct academic subdiscipline.
The decline of logical positivism reignited discussions concerning the metaphysical validity of scientific theory, specifically addressing whether such theories provide knowledge of a reality independent of human experience (scientific realism) or merely serve as predictive tools for human observations (instrumentalism). Subsequently, philosophers increasingly scrutinized the movement's tenets and historical trajectory, frequently mischaracterizing it through insufficient analysis and reducing its complexities to oversimplified notions and common stereotypes, including its perceived alignment with foundationalism.
People
- Gottlob Frege – German philosopher, logician, and mathematician (1848–1925)
- Gustav Bergmann – Austrian-born American philosopher (1906-1987)
- Kurt Grelling – German logician and philosopher (1886–1942)
- References
References
- Articles by logical positivists
Articles by logical positivists
- The Scientific Conception of the World: The Vienna Circle
- Carnap, Rudolf. 'The Elimination of Metaphysics Through Logical Analysis of Language'
- Carnap, Rudolf. 'Empiricism, Semantics, and Ontology.'
- Excerpt from Carnap, Rudolf. Philosophy and Logical Syntax.
- Feigl, Herbert. 'Positivism in the Twentieth Century (Logical Empiricism)', Dictionary of the History of Ideas, 1974, Gale Group (Electronic Edition)
Articles on logical positivism
- Kemerling, Garth. 'Logical Positivism', Philosophy Pages
- Murzi, Mauro. 'The Philosophy of Logical Positivism.'