ties to several of its leading members, including Moritz Schlick (to whom Rougier's 1955 book Traité de la connaissance is dedicated) and Hans Reichenbach. Rougier also participated as an organizer and contributor to many Vienna Circle activities, including the International Encyclopedia of Unified Science. Rougier's own contribution to the Encyclopedia never materialized, however, because he soon became one of many participants who ended up quarreling with Otto Neurath, the project's editor-in-chief. Religion Rougier's conventionalist philosophical position naturally led him to oppose Neo-Thomism, which had been the official philosophy of the Roman Catholic Church since the 1879 encyclical Aeterna Patris but was gaining particular momentum during the 1920s and the 1930s. Rougier published several works during this period attacking the contemporary revival of scholasticism, thereby earning the personal enmity of prominent Thomists such as Étienne Gilson and Jacques Maritain. Rougier's objections to Neo-Thomism were not merely philosophical, however, but formed part of a general opposition to Christianity that he had already begun to develop during his adolescence under the influence of Ernest Renan. His early opposition to Christianity continued to influence intellectual work of Rougier's maturity and led him in 1926 to publish a translation of Celsus that is still in use today. Politics Rougier was also a political philosopher in the liberal tradition of Montesquieu, Constant, Guizot and Tocqueville. Consistent with his conventionalist epistemology, Rougier believed that political power rests not upon eternally-valid claims but upon, which he called mystiques. The only possible reason to prefer one political system over another, he believed, depends not on eternal truths but purely on pragmatic grounds. In other words, political systems should be chosen not based on how "true" they are but rather on how well they work. After visiting the Soviet Union in 1932 on a visit sponsored by the French Ministry of Education, Rougier became convinced that a planned economy does not work as well as a market economy. That conviction led him to participate in the organization of the first neoliberal organization of the 20th century, the Colloque Walter Lippmann, in 1938. That year, Rougier helped to found the Centre international d'études pour la rénovation du libéralisme. The political network established by both groups eventually led to the 1947 foundation of the famous Mont Pelerin Society to which Rougier was elected in the 1960s through the personal backing of Friedrich Hayek. Rougier, as one of the founding fathers of neoliberalism,