Chapter 6 levels a devastating critique of two self-contradictions within Marxism.
Marxists claim that workers are exploited under laissez-faire capitalism. Capitalists viciously expropriate and steal workers' "labor time" in much the same manner in which feudal lords stole the time of their enthralled serfs by forcing them to cultivate the demesne. In that case, the worker is cheated of the full product of his labor. Now this is actually nonsense animated only by a lamentable failure to grasp the nature of the market process and the social function of entrepreneurs. But let's assume it for the sake of argument. How then can there be a theft by a capitalist of the worker's sustenance, unless the worker had a moral right to the fruits of his labor and in particular, owned himself? Thus, Marxists must willy-nilly accept the fact of self-ownership and all that it implies.
This has two consequences. First, it breaks apart the political alliance between socialists and welfare state "liberals." For the taxes extracted from the workers by the state, too, violate self-ownership that the socialists implicitly affirm and denude workers of the full product of their labor. Feudal lords exploit workers (both Marxists and libertarians agree); capitalists exploit workers (only Marxists think so); but also the state exploits workers (as only libertarians hold, but as Marxists, Cohen argues, are led to admit, as well).
There was indeed for a long time a tension between socialists and interventionists; as Mises pointed out,
Marx was opposed to social legislation -- social security and so forth...
On the advice of Marx himself and, after his death, of Friedrich Engels, the German Reichstag voted against socialized medicine, social insurance, and labor legislation, calling them frauds to exploit the laboring classes even more than before.
On Cohen's interpretation of Marx, communism becomes possible only under "limitless abundance." (As we have seen, there can be no such thing.) Socialism as its lower stage is supposed to develop the "material productive forces" more efficiently and speedily than any other system, until such abundance is generated. (It doesn't and in its only feasible Cuban-style form in fact kills any and all progress.) Capitalism, though causing impoverishment of the great masses of men while at the same time concentrating wealth in the hands of the very few (lies), should be left in its pure laissez-faire variety so that it could "mature" and be transcended as fast as can be. As a result, government interventionism and welfare-warfare state only delay the communist revolution.
Second, it neatly destroys Marxism's own exploitation doctrine.
Let e = in any capitalist relationship the worker is unjustly exploited, and let s be the self-ownership thesis. The Marxist's account of e (his condemnation of the capitalist as a thief) shows that he is committed to s...
But the case of the cleanly generated capitalist relationship [via libertarian just original appropriation and just transfers thereupon] shows that s disproves e. So, if e is true, s is true; but, if s is true, e is false.
And that is a reductio ad absurdum of the Marxist claim that propertyless workers are, as such, exploited. (162)
The Mensheviks can apparently reject the self-ownership thesis with less trouble for their own doctrines than the socialists can. Cohen has promised to reject it, too, though toward the end of the book.