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And here I draw my line that non-marxists as well as many Marxists won't accept: the profound importance of Ellen Meiksins Wood's _Origin of Capitalism: A Longer View.
Two points (drawn from her entire corpus):
a. Capitalism is unique among social orders in the separation of the "economy" from the state. (Jim Blaut was wrong from the beginning in failing to understand this point.) In what has been called "tributary societies," the 'economic' power of the rulers was inseparable from their power of coercion. (Wood's book on Athens is of great importance here. The democratic revolution there relieved the peasantry of all obligations to the 'eupatridae' [well-born]. Exploitation under capitalism is not grounded in coercion but on the just contract between the purchaser and the seller of labor power.
b. The 'founders' of this 'structure" had no idea whatever that they were 'founding' a new social relation. No one quite realized that capitalism existed until it had existed for two or more centuries.
This is all implicit in the first three chapters of Capital V. 1: the whole of Marx's work was insufficient to draw out all the implications of those chapters, and probably only our descendants (assuming humanity wins through to "socialism" (whatever that will be) will be able to look back and for the fun of it work out those implications.
This of course is impossibly crude. Read Wood, Postone, Tamas, Albritton, et al.
Carrol