Testing positivism

"The Murder of Professor Schlick" brilliantly illuminates an ambitious movement in philosophy

Clare Clark

On June 22, 1936, Moritz Schlick, chair of natural philosophy at the University of Vienna, was shot dead by a former student as he walked to deliver a lecture. Johann Nelböck, who had been diagnosed with schizoid psychopathy, believed Schlick was his rival in love and that he had deliberately sabotaged Nelböck’s job prospects. Reporting the crime, some German and Austrian newspapers took a different slant. Schlick’s philosophy had corrupted “the fine porcelain of the national character”; Nelböck’s bullets were guided not by madness but “by the logic of a soul, deprived of its meaning of life”. One commentator hoped that the murder would “quicken efforts to find a truly satisfactory solution of the Jewish Question”.

David Edmonds’s lively and engaging book traces the development of Schlick’s circle, later the Vienna Circle, from its formation after the First World War to the 1930s, when the rise of the Third Reich forced most of its members into exile. This group of “scientifically literate scholars” included philosopher Rudolf Carnap, logician Kurt Gödel, mathematician Hans Hahn, and charismatic sociologist Otto Neurath, a proselytising leftist of such outsized stature that he signed his letters with a drawing of an elephant. Though much divided these thinkers, they were bound by a common enemy: metaphysics. Drawing on the work of Bertrand Russell and the physicist-philosopher Ernst Mach (who gave his name to the speed of sound), and with (non-Circle member) Wittgenstein as their unwilling guiding star, they argued that science was a logical structure built through the accretion of experience. Only statements that were empirically verifiable had meaning. By definition, therefore, any assertion that relied instead on reason or intuition, assertions about ethics, say, or God, was meaningless: it asserted nothing at all. For a time, mid-century, the Circle’s logical positivism was, in Edmonds’s words, the “most ambitious and fashionable movement in philosophy”.

The Murder of Professor Schlick provides a clear, accessible introduction to the complexities of logical positivism and its many proponents (Edmonds includes a helpful dramatis personae). It also brilliantly illuminates why and how the philosophy burned so brightly. For scientists, the first decades of the 20th century were a time of seismic change. Alongside Einstein, physicists such as Planck, Bohr and Heisenberg were overturning the common sense laws of Newtonian mechanics and in doing so posing previously unthinkable philosophical difficulties. Since Kant, philosophers had upheld the notion of synthetic a priori truths, truths that could be deduced without any knowledge of the world and which created the basis for understanding it: the shortest distance between two points is a straight line, say, or all events have a cause. Einstein’s theories defied the validity of these truths. Crucially, too, they were testable.

Relativity had no politics but, as fascism burgeoned, so too did the recasting of Einstein’s work as “alien” physics, a euphemism for Jewish. The same hostility attached itself to logical positivism. Cosmopolitan “Red Vienna”, a crucible of modernism, was home to the largest Jewish population in the German-speaking world: most of the Vienna Circle (though not, ironically, Schlick himself) were Jewish or half-Jewish or married to Jews. More importantly, in its determination to upend the old order, their thinking was deemed to be “Jewish”: as the Viennese philosopher Otto Weininger wrote, “the spirit of modernity is Jewish, no matter how one looks at it”. Not everyone in the Circle shared Neurath’s view that logical positivism was integral to the struggle against fascism but, in its quest precisely to distinguish sense from nonsense, truth from fiction, there is no doubt it represented a threat to the Nazi authorities. In 1935 the Circle was accused of propagating a new logic “that distinguishes itself from Aryan logic”. By 1938, when the Anschluss brought Austria under Nazi rule, most of its members had fled Vienna for good.

These academic refugees brought logical positivism to the UK and the USA where it briefly flourished. It did not endure. The British philosopher, A.J. Ayer, a one-time evangelist, asserted in the 1970s that the greatest defect of logical positivism was that “nearly all of it was false”. What is less well remembered is that he qualified this statement by adding that it was “true in spirit”. Edmonds acknowledges that the Vienna Circle is now generally regarded as a “long philosophical cul-de-sac” but, in this post-truth era of fake news and populist nationalism, he stresses the enduring importance of that spirit, its legacy of intellectual rigour, the interrogation of meaning and “the calling out of nonsense”.

At his trial for Schlick’s murder, Nelböck was found guilty: in place of the death penalty, a sympathetic judge sentenced him to ten years in prison. A year later, in 1938, the Nazis granted him a conditional release. By then the Jews in Vienna could no longer rely on logic or the truth to save them.


The Murder of Professor Schlick: The Rise and Fall of the Vienna Circle
By David Edmonds
Princeton University Press, 336pp, £22.00

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