leading source of Western Marxism, starting with the Frankfurt School, and even influenced Heidegger's Sein und Zeit (1927). Lukács then went to Moscow in the beginnings of the 1930s where he would continue his philosophical studies, and returned to Hungary after World War II. He then took part in Imre Nagy's government in 1956, and was closely watched afterwards. Lev Vygotsky's (1896–1934) studies in developmental psychology, which opposed themselves to Ivan Pavlov's works, would be expanded in the activity theory developed by Alexei Nikolaevich Leont'ev, Pyotr Zinchenko (a member of Kharkov School of Psychology), and Alexander Luria, a neuropsychologist who developed the first lie detector. After the 20th Congress of the CPSU Nevertheless, the conditions for creative philosophical work began to emerge in the mid-1950s, after the 20th Congress of the CPSU in 1956, albeit only on the 'outskirts' of philosophy: the philosophy of the natural science (B. Kedrov, I. Frolov), theory of perception and gnoseology (P. Kopnin, V. Lektorsky, M. Mamardashvili, E. Ilyenkov), the history of philosophy (V. Asmus, A. Losev, I. Narski), ethics (O. Dobronitski), aesthetics (M. Kagan, L. Stolovitsh), logics (G. Shchedrovitsky, A. Zinovyev) and semiotics and system theories (J. Lotman, who set up the Sign Systems Studies journal, the oldest semiotics periodical; V. Sadovsky). The works of the young Marx, such as the Economic and Philosophical Manuscripts of 1844, which had been first published in 1932 but suppressed under Stalin because of its incomplete break with German Idealism, also started being discussed. Others 1) Vasily Nalimov (1910-1997) was interested mainly in the philosophy of probability and its biological, mathematical, and linguistic manifestations. He also studied the roles of gnosticism and mysticism in science. Nalimov is usually credited with proposing the concept of citation index. 2) The so-called "communist morality" was an important part of Soviet Union philosophy. According to Lenin and Stalin, morality should be subordinated to the ideology of proletarian revolution. Denying the validity of religion-based morality, they wrote: what is useful to us (the Soviet people) is moral, what is harmful to us is immoral. Morality is a weapon in class struggle. Party and Komsomol members were drilled to accept that position, and to act accordingly. Publications and propaganda The USSR published voluminous materials to disseminate its philosophical ideals and justifications. These took the form of academic or professional journals or notes in the pattern of peer-reviewed material. For example, the book below challenges