Russian Formalism cannot be understood or presented as a coherent "school" of thought; for one thing, "Russian Formalism" is a generic name used to define two quite distinct movements: the OPOJAZ (Obscestvo izucenija POeticeskogo JAZyka - Society for the Study of Poetic Language) in St. Petersburg and the Linguistic Circle in Moscow. More importantly, Russian Formalism did not produce any unified doctrine and no general consensus can be found between its proponents on a central and common aim to their endeavours. Formalism is, in fact, an extremely diverse and heterogeneous movement, whereby it is generally considered more precise to refer to the "Russian Formalists", rather than to the more encompassing and abstract term of "Formalism".
Moreover, it is important to bear in mind that, despite now being the accepted term, "Formalism" was a tag imposed from the outside by the adversaries of the movement, and as such it conveys a meaning explicitly rejected by the Formalists themselves. Thus, in the words of one of the foremost Formalists, Boris Eichenbaum: "It is difficult to recall who coined this name, but it was not a very felicitous coinage. It might have been convenient as a simplified battle cry but it fails, as an objective term, to delimit the activities of the "Society for the Study of Poetic Language...."[1]
Bearing in mind the above mentionned considerations, it may seem unwise to try to provide any kind of unified summary of the main themes of the Formalists. With all due caution however, there is one idea that can be found to unite all the Formalists, i.e. the autonomous nature of poetic language and its specificity as an object of study for literary criticism. Thereby is meant that, generally speaking, the Formalists' main endeavour consisted in defining a set of properties specific to poetic language (be it poetry or prose) recognisable by their "artfulness" and consequently analysing them as such. A clear illustration of this, may be provided by the main argument of one of Viktor Shklovsky's -the founder of the OPOJAZ- early text, "Art as Device" (Iskusstvo kak priem, 1916): art is a sum of literary and artistic devices, that the artist manipulates to craft his work.
Shklovsky's main objective in "Art as Device" is to dispute the conception of literature and literary criticism common in Russia at that time. Broadly speaking, literature was considered, on the one hand, to be a social or political product, whereby it was then interpreted (in the tradition of the great critic Belinsky) as an integral part of social and political history. On the other hand, literature was considered to be the personal expression of an authors world vision, expressed by means of images and symbols. In both cases, literature is not considered as such, but evaluated on a broad socio-political or a vague psychologico-impressionistic background. The aim of Shklovsky is therefore to isolate and define something specific to literature (or "poetic language"): this, as we saw, are the "devices" who make up the "artfulness" of literature.
Obviously, Formalists do not agree between each other on exactly what is a "device" (priem), nor how these devices are used or how they are to be analysed in a given text. The central (and revolutionary) idea however is more general: poetic language posseses specific properties, which can be analysed as such. This, it may be argued, was already the view defended by Aristoteles in his "Poetics";
[1] Boris Eichenbaum, "Vokrug voprosa o formalistah" (Around the question on the Formalists), Pecat' i revolucija, no5 (1924), pp.2-3.