Verifiable Truths

The thinkers who tried to strip metaphysics from philosophy

A tram in Vienna, Austria (Luca Sartoni, Flickr/lucasartoni)
A tram in Vienna, Austria (Luca Sartoni, Flickr/lucasartoni)

The Murder of Professor Schlick: The Rise and Fall of the Vienna Circle by David Edmonds; Princeton University Press, 336 pp., $26.95

“There are two types of philosophers,” I heard as an Oxford graduate student. “One writes balderdash, while the other writes Balderdash!” The Vienna Circle (known as logical empiricists and, later, as logical positivists) typifies the second type.

Austria between the world wars fostered an extraordinary number of talents in diverse fields: Sigmund Freud in psychology, Arnold Schoenberg in music, Karl Kraus in journalism, Robert Musil in literature, Gustav Klimt in art, the Bauhaus in architecture, and the “Austrian school” in economics. In some of these areas, the overriding ethos was hostility to what the Bauhaus called “ornament.” The Vienna Circle of philosophers, led by Moritz Schlick, hoped to cleanse philosophy of anything vague or, to use their favorite term of abuse, “metaphysical.” Some members also aspired to provide firm foundations for knowledge, an ambition that can be traced back to Descartes and the 17th-century rationalists.

They hoped to realize this ambition by rethinking the bases of mathematics and science. As British philosopher David Edmonds points out in this informative and well-written account, by “science” the Circle philosophers meant physics because, surprisingly enough, they were ignorant of recent major innovations in biology.

Heavily influenced by Ludwig Wittgenstein, whom many of them treated like a Hebrew prophet, they sought to rule out of court most traditional questions of philosophy. In their view, statements could be meaningful in only two ways: either logically, like the truths of mathematics, or empirically. Anything else was, as philosophers like to say today, “not even wrong,” but simply senseless (sinnlos). As Schlick explained, “The empiricist does not say to the metaphysician ‘what you say is false’ but, ‘what you say asserts nothing at all.’”

This approach led to a number of intriguing ideas, like “verificationism.” A statement about the world could be meaningful only if empirically verifiable, argued the influential Circle philosopher Rudolph Carnap. Metaphysical statements could not be verified empirically, and so were not meaningful. The same seemed to be true of ethical statements, since one can cannot empirically verify that “murder is wrong.”

One solution was to treat ethical statements as descriptive rather than prescriptive. Like an anthropologist, the philosopher should simply examine what people have considered wrong. Another solution, if it can be called that, was the “hoorah/boo!” account of ethics: saying “lying is wrong” is equivalent to saying the word “lying” followed by a disapproving sound. “Generosity is good” is the same as “Generosity, hoorah!” Similar difficulties occurred with aesthetic judgments.

Circle members never arrived at an adequate formulation of verificationism. Is the statement “there is water on the far side of the moon,” which cannot be verified, meaningless? It certainly does not seem so. What’s more, physics affirmed the existence of nonobservable entities, and no one wanted to declare these affirmations meaningless. Perhaps one ought to say verificationism meant verifiable in principle? In that case, isn’t the affirmation of an afterlife a meaningful statement? As Schlick argued, when you die, you will see. And then there was the apparently fatal objection that the verification principle itself could be proven neither logically nor empirically.

We should not be surprised, therefore, that some of the school’s greatest contributions came from its dissenters. One Circle member, the mathematician Kurt Gödel, rejected the idea that mathematical statements are tautologies, statements ultimately resembling “all bachelors are unmarried.” A mathematical Platonist, Gödel believed that “there were truths ‘out there’ … that were not constructed by human minds. They existed independently of minds, and could be discovered by mathematicians.” Neither tautologies nor empirically verifiable, these truths were nevertheless not meaningless. Gödel’s famous incompleteness theorem, which states that in any consistent formal system of a certain complexity there are truths that cannot be proven, is one of the greatest mathematical achievements.

Schlick refused to admit the belligerent Karl Popper into the Circle, but Edmonds still treats him as a sort of member. Popper’s The Logic of Scientific Discovery (1934), an influential work if there ever was one, insisted that scientific knowledge was not the sort of thing that could be proven once and for all. The scientist rather offers his statements as “falsifiable.” There must be a way that these statements could turn out to be wrong, and even Newton’s Laws, which had seemed absolutely certain, were eventually superseded.

Also the author of The Open Society and Its Enemies (1945), Popper achieved renown for his antitotalitarian philosophy. By contrast, Otto Neurath, a philosopher and Marxist political economist, participated in the Moscow-backed attempt to set up a Bavarian Soviet Republic, and in the group’s manifesto—without the knowledge of members whose names were appended to it—linked the Circle to radical politics. Edmonds deftly elucidates the Circle’s ideas and ably sketches how the rise of Naziism eventually forced Circle members to emigrate. But his ignorance of Soviet Marxism leads to some odd statements and omissions.

Explaining Neurath’s work for the Soviet government, Edmonds observes, “that country’s dictatorial turn,” which Neurath did not see, “had already been apparent to more perspicacious visitors” to the USSR. But there was no “dictatorial turn”: Lenin’s Bolsheviks had proclaimed a dictatorship from the start, immediately established secret police to wipe out all “class enemies” regardless of beliefs or actions, and heaped contempt on those who believed in tolerance or compassion.

Edmonds observes that Circle members rejected the Nazi idea that collective entities, like “society,” are more real than the individuals composing it, but he does not seem aware that Soviet Marxism also regarded collective entities—social classes—as more real than individuals. One wonders how Neurath reconciled his Marxism with the Circle’s methodological individualism.

The influence of the Vienna Circle is still with us. “By any reasonable understanding of analytic philosophy,” Edmonds points out, “the Circle is part of its DNA.” The Circle inspired game theory, so important to modern economics. A few shortcomings notwithstanding, The Death of Professor Schlick is a book that everyone interested in the intellectual history of the 20th century should want to read.

Permission required for reprinting, reproducing, or other uses.

Gary Saul Morson is a member of the American Academy of Arts and Sciences and teaches Russian and world literature at Northwestern University. His latest book, Wonder Confronts Certainty: Russian Writers on the Ultimate Questions and Why Their Answers Matter, will be published next year.


Please enter a valid email address
That address is already in use
The security code entered was incorrect
Thanks for signing up