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.
Types of socialism
Trotskyism is the theory of Marxism as advocated by Leon Trotsky. Trotsky considered himself a Bolshevik–Leninist, arguing for the establishment of a vanguard party. He considered himself an advocate of orthodox Marxism. His politics differed greatly from those of Stalin or Mao, most importantly in declaring the need for an international "permanent revolution" and arguing that democracy is essential to both socialism and communism. Numerous groups around the world continue to describe themselves as Trotskyist and see themselves as standing in this tradition, although they have diverse interpretations of the conclusions to be drawn from this.