There is an analogy here with the Christian interplay between divine providence and human free will. For the Christian, I act freely when I strangle the local police chief; but God has foreseen this action from all eternity and included it all along in his plan for humanity. He did not force me to dress up as a parlor maid last Friday and call myself Milly; but being omniscient, he knew that I would, and could thus shape his cosmic schemes with the Milly business well in mind. When I pray to him for a smarter-looking teddy bear than the dog-eared, beer-stained one who sleeps on my pillow at present, it is not that God never had the slightest intention of bestowing such a favor on me but then, on hearing my prayer, changed his mind. God cannot change his mind. It is rather that he decides from all eternity to give me a new teddy bear because of my prayer, which he has also foreseen from all eternity. In one sense, the coming of the future kingdom of God is not preordained: it will arrive only if men and women work for it in the present. But the fact that they will work for it of their own free will is itself an inevitable result of God’s grace.There is a similar interplay between freedom and inevitability in Marx… . Marx does not think that the inevitability of socialism means we can all stay in bed. He believes, rather, that once capitalism has definitively failed, working people will have no reason not to take it over and every reason to do so… . Just as for the Christian human action is free yet part of a preordained plan, so for Marx the disintegration of capitalism will unavoidably lead men and women to sweep it away of their own free will.
Ah, the power of analogy. Terry Eagleton, Why Marx Was Right.