The members of the Vienna Circle, a group of philosophers and scientists, formulated principles for a genuinely scientific philosophy. The result, logical positivism, became one of the most important and influential philosophical movements of the twentieth century.

By the late nineteenth century, the University of Vienna had established itself as a stronghold of empiricism and positivism, and in 1895, the acclaimed physicist and positivist philosopher Ernst Mach was appointed to a chair in philosophy of inductive science. According to Mach’s antimetaphysical positivism, the goal of science is to formulate laws to describe and predict experience, and any attempt to explain experience in terms of imperceptible realities is merely speculative metaphysics. Vienna Circle
Logical positivism
Philosophy;logical positivism
Ernst Mach Association
Schlick Circle
[kw]First Meeting of the Vienna Circle (1922)
[kw]Vienna Circle, First Meeting of the (1922)
Vienna Circle
Logical positivism
Philosophy;logical positivism
Ernst Mach Association
Schlick Circle
[g]Austria;1922: First Meeting of the Vienna Circle[05520]
[c]Philosophy;1922: First Meeting of the Vienna Circle[05520]
Schlick, Moritz
Mach, Ernst
Frank, Philipp
Hahn, Hans
Neurath, Otto
Feigl, Herbert
Waismann, Friedrich
Carnap, Rudolf
Gödel, Kurt
Wittgenstein, Ludwig

In 1908, a group of academics in Vienna, including Philipp Frank, Hans Hahn, and Otto Neurath, began meeting in order to promote Mach’s positivistic conception of science. When Mach’s chair became vacant in the early 1920’s, his fellow philosophers urged that it should be filled by someone who would continue Mach’s legacy. These thinkers came to champion the candidacy of Moritz Schlick, a German physicist and philosopher who had been one of the first to argue that Albert Einstein’s general theory of relativity supported Mach’s positivism.

When Schlick arrived in Vienna in 1922, a discussion group of philosophers, scientists, and mathematicians quickly formed around him, and under his leadership the group began meeting on Thursday evenings in the department of mathematics. In addition to Frank, Hahn, and Neurath, the group included Herbert Feigl and Friedrich Waismann. A few years later Rudolf Carnap joined, as did mathematician Kurt Gödel. The group was known for a time as the Ernst Mach Association and later as the Schlick Circle, but in the late 1920’s the members began calling themselves the Vienna Circle.

Ernst Mach.

(Library of Congress)

Membership was by invitation only; at its peak, the organization included about three dozen members. In addition to Mach’s positivist philosophy, one of the primary influences on the circle was the British empiricism propounded by David Hume and John Stuart Mill. (Empiricism is the epistemological theory that holds that all knowledge is ultimately based on perception or sensory experience.) Another influence came from the advances made in the field of logic by Gottlob Frege and Bertrand Russell, who proposed that mathematics is reducible to logic. The circle was also strongly influenced by Ludwig Wittgenstein’s book Tractatus Logico-Philosophicus (1922; English translation, 1961). Tractatus Logico-Philosophicus (Wittgenstein) Schlick immediately recognized the book’s importance and invited Wittgenstein to attend the circle’s meetings. Although Wittgenstein never became a member, his thought had a profound impact on the development of the Vienna Circle’s logical positivism.

The verifiability criterion of meaning Verifiability criterion of meaning is the central thesis of logical positivism and is the basis of many of its other doctrines. The basic idea is that a proposition is meaningful only if it is empirically verifiable—that is, only if it is possible to specify which experiences would show that the proposition is either true or false. In general, then, propositions that are not verifiable are declared meaningless or nonsensical. Although Vienna Circle members disagreed about whether verification had to be conclusive or whether weaker degrees of verification would suffice, all members accepted some version of the verifiability criterion. One consequence of their acceptance of the criterion was that, since traditional metaphysical philosophy does not satisfy the criterion, they came to the conclusion that traditional philosophical doctrines are worthless and should be abandoned. If metaphysics is conceived to be an a priori and nonempirical inquiry into the nature of the world, an inquiry that by its nature must transcend the limits of experience, then such an inquiry can produce only nonsense. Furthermore, if metaphysics produces only nonsense, the role of philosophy should be restricted to the logical clarification of scientific propositions. Not surprisingly, these ideas were greeted with hostility by many more-traditional philosophers.

Some of the other distinctive doctrines of the Vienna Circle emerge when other types of propositions that do not satisfy the verifiability criterion are considered. Ethical propositions are obviously not empirically verifiable (for example, what experiences would verify that torturing animals is wrong?), but clearly ethical propositions play too central a role in human life to be declared nonsensical and abandoned. One of the ways the Vienna Circle dealt with this problem was by interpreting ethical propositions not as assertions but as exclamations that express attitudes toward actions or persons. Thus, for example, to say that torturing animals is wrong is to express one’s disapproval of that sort of action.

Similarly, the propositions of logic and mathematics cannot simply be given up just because they cannot be explained through empirical verification. Logical and mathematical propositions are necessarily true and are knowable a priori—that is, without recourse to any kind of empirical investigation. The positivists solved this problem by holding that logical and mathematical propositions are tautologies, propositions that are true in virtue of certain linguistic conventions and thus true in virtue of meaning alone.

The Vienna Circle reached the height of its influence in the early 1930’s. In 1930, the circle took editorial control of the journal Erkenntnis (the German word for “knowledge”), which then began to publish articles sympathetic to logical positivism. Schlick and Neurath were the general editors of a series of monographs issued under the title International Encyclopedia of Unified Science, which promoted the ideas of the Vienna Circle. During this period, the Vienna Circle organized a series of conferences in major European cities that accelerated the spread of logical positivism. The group’s rise, however, was brought to an end by the rise of Nazism in Germany and Austria. Because many logical positivists were Jewish, socialist, or both, most were forced to flee continental Europe: Waismann and Neurath went to Great Britain, where Wittgenstein had been since 1929, and Carnap, Feigl, Frank, and Gödel emigrated to the United States, where they did much to establish logical positivism in North America. Hahn died in 1934 in Vienna, and Schlick was murdered on the steps of a University of Vienna lecture hall by a deranged student with Nazi sympathies in 1936. By 1938, the Vienna Circle had effectively ceased to exist.

It is ironic that while the rise of Nazism ultimately destroyed the Vienna Circle, the fact that most of its members had to flee to other countries only accelerated the spread of logical positivism and transformed it into an international movement. Logical positivism flourished in Great Britain, North America, and Scandinavia until the 1950’s and 1960’s, when it was supplanted by other philosophical movements. It fell out of favor partly because it was never able to formulate an adequate version of the verifiability criterion of meaning, and partly because its account of the inherent truths of logic and mathematics turned out not to be defensible.

Although the age of logical positivism ended, the ideas of the Vienna Circle continued to influence philosophy. The members’ commitment to clarity and rigorous argumentation continues to inspire philosophers in the analytic tradition, and their view that it is empirical science, rather than mathematics or philosophical speculation, that provides a paradigm of human knowledge came to be widely accepted. For those who deplore contemporary, “postmodern” forms of relativism and irrationalism, the Vienna Circle’s embodiment of the Enlightenment ideals of rationality and the unbiased search for truth remains a shining example of human inquiry at its best. Vienna Circle
Logical positivism
Philosophy;logical positivism
Ernst Mach Association
Schlick Circle

• Ayer, A. J. Language, Truth, and Logic. New York: Dover, 1952. First published in 1936, this was the first full-length presentation in English of the ideas of the Vienna Circle. A clear and trenchant introduction to logical positivism.
• _______. Logical Positivism. New York: Free Press, 1959. A valuable collection of key papers by members of the Vienna Circle and other logical positivists.
• Carnap, Rudolf, Hans Hahn, and Otto Neurath. “The Scientific Conception of the World: The Vienna Circle.” In Empiricism and Sociology, edited by M. Neurath and R. S. Cohen. Boston: Kluwer Academic, 1973. Originally issued as a pamphlet in 1929, when it was published in Schlick’s honor after he refused an attractive offer from the University of Bonn and stayed in Vienna. Written in the style of a political manifesto, it provides a nontechnical account of the central tenets of the Vienna Circle.
• Friedman, Michael. Reconsidering Logical Positivism. Cambridge, England: Cambridge University Press, 1999. A collection of essays focusing on the central figures of the Vienna Circle by a noted expert in the history of early analytic philosophy.
• Jørgensen, Jørgen. The Development of Logical Empiricism. Chicago: University of Chicago Press, 1951. An account of the circle written by a Danish philosopher who participated in some of their meetings.
• Stadler, Friedrich. The Vienna Circle: Studies in the Origins, Development, and the Influence of Logical Empiricism. New York: Springer, 2000. In-depth study of logical positivism and the Vienna Circle draws on previously unavailable archival material.

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