The first concept was worked out by the official leaders of Soviet science, such as B. D. Grekov and B. A. Rybakov, Members of the Academy of Sciences. According to their concept, the Eastern Slavs (living from the time immemorial on the same territories as at the present) had discovered — some thousands years В. C. — the plough agriculture, created the state, and developed a pagan religion that came very close to Christianity.
The second concept was presented by the officially disgraced scholar, Professor Vladimir Propp, one of the founders of Soviet semiotics (he was one of the leaders of world structuralism as well). Propp has observed that Russian agricultural festivals, which are highly seasonal, demonstrate a stable set of common features (due, he said, mainly to the similarity of peasant working conditions). Since these festivals totally lack any developed gods, the inference was that the underlying Russian paganism was totally devoid of them, being of an especially archaic nature (like in the views of Anichkov, Niederle and Veselovsky). Such figures as Kupalo, Yarilo and the like, were «underdeveloped deities».
V. Propp's opinions added an additional impulse to the legacy of the work done by the Russian ethnographer of the older generation, Dmitriy Zelenin, who had studied Slavic demonology with the retrospective method. His follower was Nikita I. Tolstoy, the grand-grandson of Leo Tolstoy. Member of the Academy of Sciences, he had built an influential school of ethnographers and ethnolinguists. So, the third major concept of Slavic Paganism emerged, aimed at reconstructing the old pagan religion using the exclusively ethnographic material. Naturally it could throw to the past only what remained kept in the living culture, i. e. no major gods. Thus the most prominent professional ethnographers, ethnolinguists, and folklorists have accepted the idea of the ancient Slavs having only lower mythology (demonology).
The fourth concept was offered by Vyacheslav Ivanov and Valdimir Toporov, also structuralists and (if for no other reason than this) considered by the regime as frondeurs. They used the names of Slavic gods as their main source and compared them with other Indo-European names, social terms, and myths. On this basis they began reconstructing a developed mythology derived from the common Indo-European substrate (the «Basic Myth», the initial struggle of Perun against Volos -Veles, etc.). Their methodology was to a great extent borrowed from Levy-Strauss. It allowed them to reach such freedom of making connections that the results of their reconstructions became very rich, but, alas, lost the reliability. There is no direct proof of the struggle of Perun against Volos (and Volos, as distinct from Veles, probably is at all a new god, most likely having emerged as a transformation of the Christian Saint Vlasius/ Blasius, Bulgarian Vlas).