Whether or not Leninism is real Socialism is a different question (there's a reason, though, why other socialists, including Marxists, have called it State Capitalism, though.)!
What is undisputable is that these are three different things:
1. Recognizing the conflict between labor and capital as a real and significant factor in capitalist society, and
2. Advocating Marxism, and
3. Advocating Leninism.
The societies in which Marxism has been most broadly applied are the developed “capitalist” societies, which have generally evolved from what Marx described as capitalism to what has been called (among other things) as “the modern mixed economy”, by adopting both elements of programs of various (in many cases, Marxist) critics of capitalism, or compromise positions.
There are also societies, which never were mature capitalist societies, that have tried to bypass mature capitalism and apply the Leninist course. Advocates laissez-faire capitalism like to point to these as a broad argument against socialism, while advocates of non-Leninist socialism tend to point to them as as arguments against the Leninism as a useful approach to socialism, whether or not they accept it as a genuine socialism.
That was certainly true under feudalism, which is probably why the modern capitalist center-to-right and pro-labor/socialist left all have roots in classical liberalism.
But as capital has matured, capital as a class has effectively subsumed the landed class, largely by driving land into fee-simple ownership.
I don't think it's fair to call a modern mixed economy "Marxist". Marx didn't really advocate anything in particular in terms of economic organization. He had no clear idea of how his world would operate, and that's why Leninism was able to fill the void in the way that it did.
Marx's ideas were fundamentally negative in nature. He was opposed to things, and had sharp and perceptive critiques of capitalism, but he didn't really present an alternative. To the extent that he did articulate a vision, it doesn't really seem like, e.g. Sweden would really fit the bill, though.
> I don't think it's fair to call a modern mixed economy "Marxist".
It's at least as fair as it is to call Leninism Marxist.
> Marx didn't really advocate anything in particular in terms of economic organization.
Yes, he did.
> Leninism was able to fill the void in the way that it did.
Leninism didn't fill a void, it made deliberate changes to apply to very different conditions those addresses by Marx’s writing (which addressed mature capitalist societies and where he saw that they should go next to resolve problems he saw as inherent to their system.)
> but he didn't really present an alternative.
Yes, he did, though Marx was very big on path dependency, so his recommendations were more specific when directed at more specific conditions. Capital is pretty pure critique of the then-status-quo, The Communist Manifesto has a fairly broad program, but narrower and less-well-known works like the Demands of the Communist Party in Germany, Programme of the French Workers Party have quite specific policy proposals.
It seems like we disagree about what it means to actually propose policy.
> Capital is pretty pure critique of the then-status-quo
Yep.
> The Communist Manifesto has a fairly broad program
The Communist Manifesto doesn't do much policy proposing. Workers owning the means of production is about as far as it goes, and to the extent that that his Marx's proposal...that isn't realized anywhere in Europe.
> but narrower and less-well-known works like the Demands of the Communist Party in Germany
These are both pretty short and vague, but they are policy proposals. However, they are both pretty clearly not an articulation of his vision for the post-revolution society he describes in The Communist Manifesto. They are pragmatic demands for political parties to make of their governments.
Let's compare. The Communist Manifesto:
> In this sense, the theory of the Communists may be summed up in the single sentence: Abolition of private property.
Demands of the communist party in Germany:
> 15. Introduction of strongly progressive taxes and abolition of taxes on consumption.
So, here's the fundamental issue: When Marx is specific, he's mild. His specific ideas are totally bland, and not at all unique to him. He would be a footnote of history if his specific ideas were all he said. When we refer to "Marxism", we refer to the actually novel idea: Abolition of private property. But of course, it is here that he is vague. He gives no indication of how a society without private property might actually function. And it is into exactly that void that Leninism stepped. It did so because it had no choice.
Lenin understood that they didn't have a revolution to institute a minimum wage. They had a revolution to abolish private property. But Marx had no clue how to manage such a society, and as it turns out, neither did Lenin.
What is undisputable is that these are three different things:
1. Recognizing the conflict between labor and capital as a real and significant factor in capitalist society, and
2. Advocating Marxism, and
3. Advocating Leninism.
The societies in which Marxism has been most broadly applied are the developed “capitalist” societies, which have generally evolved from what Marx described as capitalism to what has been called (among other things) as “the modern mixed economy”, by adopting both elements of programs of various (in many cases, Marxist) critics of capitalism, or compromise positions.
There are also societies, which never were mature capitalist societies, that have tried to bypass mature capitalism and apply the Leninist course. Advocates laissez-faire capitalism like to point to these as a broad argument against socialism, while advocates of non-Leninist socialism tend to point to them as as arguments against the Leninism as a useful approach to socialism, whether or not they accept it as a genuine socialism.