argued that the capitalist system is not properly anarcho-capitalist because it so often colludes with the state, writing: "The difference between free-market capitalism and state capitalism is precisely the difference between, on the one hand, peaceful, voluntary exchange, and on the other, violent expropriation. State capitalism inevitably creates all sorts of problems which become insoluble". According to Rothbard, "what Marx and later writers have done is to lump together two extremely different and even contradictory concepts and actions under the same portmanteau term. These two contradictory concepts are what I would call 'free-market capitalism' on the one hand, and 'state capitalism' on the other". However, despite Rothbard's claims, Marxists do make a distinction between free-market capitalism and state capitalism. The term state capitalism was first used by Marxist politician Wilhelm Liebknecht in 1896 and Friedrich Engels, who developed Marxist theory, talked about capitalism with state ownership as a different form of capitalism. Rothbard maintained that anarcho-capitalism is the only true form of anarchism—the only form of anarchism that could possibly exist in reality as he argues that any other form presupposes an authoritarian enforcement of political ideology such as "redistribution of private property". According to this argument, the free market is simply the natural situation that would result from people being free from authority and entails the establishment of all voluntary associations in society such as cooperatives, non-profit organizations, businesses and so on. Moreover, anarcho-capitalists as well as classical liberal minarchists argue that the application of anarchist ideals as advocated by what they term left-wing anarchists would require an authoritarian body of some sort to impose it. Based on their understanding of anarchism, in order to forcefully prevent people from accumulating capital, which they believe is a goal of those anarchists, there would necessarily be a redistributive organization of some sort which would have the authority to in essence exact a tax and re-allocate the resulting resources to a larger group of people. They conclude that this body would inherently have political power and would be nothing short of a state. The difference between such an arrangement and an anarcho-capitalist system is what anarcho-capitalists see as the voluntary nature of organization within anarcho-capitalism contrasted with a centralized ideology and a paired enforcement mechanism which they believe would be necessary under a "coercively" egalitarian-anarchist system. On the other hand, anarchists argue that a state is required to maintain private property and