Edmonds repeatedly discusses the sometimes ambivalent relationship between the Vienna Circle in philosophy and Austro-Marxism in politics. You might call it ... some sort of waltz. But let us begin with Mach. Ernst Mach was a scientist and philosopher who flourished circa 1900. As a philosopher, he believed that sense perception is the paradigm of all knowledge and that scientific laws, mathematics, and the postulation of unseen entities like magnetic fields, are all simply ways of describing and predicting sense perception. This notion, which came to be called "empirio-criticism," would in time have a great influence on the Vienna Circle. Aside from geography and chronology, Austro-Marxism would seem unrelated to empirio-criticism. The former was an ideology closely associated with Bruno Bauer, the head of Austria's Social Democratic Workers' Party from 1918 to 1934. In '34, as fascists tightened their control in Austria (though at this time they were fasc...