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.
Michael Hudson (economist)
Although Hudson's views are unpopular amongst other Marxists and sometimes vehemently rejected by them, his views converge with later writings of Marx himself. Hudson quibbles that most Marxists never go beyond "Capital, Volume I", where Marx assumes there is a rent-free market where all commodities are sold at their values. That is how Marx deduces the exploitative nature of capitalism and labour-capital dichotomy as its underlying contradiction, but in "Capital, Volume II" and "Capital, Volume III" he relaxes his assumptions and discovers other contradictions that are much closer to what can be observed in today's economic system. In "Capital, Volume III", Marx discusses the tendency of productivity and supply to increase at a faster pace than the consumption power and demand. Marx also revised his earlier ideas as he studied and learned more about the asymmetric development of capitalism. This ultimately led him to soften his revolutionary tone as he realized how dominance of an industrially advanced nations over underdeveloped nations and blocks revolutionary tendencies amongst working classes of dominating nations. On the other side, Marx clashed with Karl Schapper, suggesting that the idea of workers taking over the state power ends up in disaster because they are not ready to practice that power.