Value-form
The Western Left academics are nowadays very happy to talk about "varieties of capitalism", but talking about "varieties of socialism" remains almost an absolute "no-no". Most Marxists continue to believe in "only one" (Marxian) socialism: either that, or nothing at all. "Either" a society or movement conforms to the true concept of socialism, "or" it does not; and if it does not, it "cannot be" socialism. However, precisely "because" there are many different Marxist beliefs about socialism, Marxists cannot agree among themselves whether Soviet-type societies were socialist, capitalist, or something else. Some countries meet with the moral expectations which Marxists have, and others do not.Originally Marx and Engels themselves had heckled the advocates of "true socialism", but later Friedrich Engels and Karl Kautsky promoted Marxist socialism as the one and true "scientific socialism" within the Socialist International. When he was 43 years old, Lenin stated: "The Marxist doctrine is omnipotent because it is true". Lenin's Communist International (a deliberate split with the social democrats) adopted Marxist socialism as its official political doctrine.
Permanent revolution
Since Marxism emphasises the contingency of political developments on material historical circumstances (as against 'idealism'), it is worthwhile to have some idea of how Marx saw the context in which he advocated "permanent revolution". It seems that he believed that "the first act of the approaching revolutionary drama [in Germany] will coincide with the direct victory of their own class in France and will thereby be accelerated". That is, the petty-bourgeois are expected to come to power in Germany at the same time as the 'direct victory' of the proletariat in France. Furthermore, Marx seems to believe that the former (and hence, of both) is "imminent" (c.f. the third paragraph of the "Address"). Marx clearly believes, therefore, that Europe is entering a time, and is at a level of development of the "productive forces", in which the proletariat have the social revolution within their reach. Though circumstances did not develop as anticipated, at the dawn of the 20th century leading into the first World War and the Russian Revolution this observation proved accurate.