>However, in capitalism, the surplus is alienated from the producers,
>becoming a coercive force against them, precisely because of the
>spontaneous character of market relations.
>
>As long as the allocation of society's resources (principally,
>productive labour itself) is decided by the spontaneous and unplanned
>operation of the market, then the surplus will always have the form of
>an external coercive force.
I would take an issue with the characterisation of the market as 'spontaneous.' That is the characterisation of the market by bourgeois political economy, which marx mocked by comparing it to religion: "ours is god-given, everyone elses - man made." "Market" is an abstraction, an illusion that hides the institutional mechanisms of capitalist rule: coprorations, cartels, trusts, government policies etc. IMHO, the underappreciation of the institutional aspects of capitalism weakens marxist argument:
if, as you argue, the issue is not the existence of surplus per se but its distribution, and if under the capitalist rule that surplus is distributed by 'spontaneous' markets - then it is difficult to rebutt the chief claim of bourgeois economics that market is a "natural" institution aimed at efficiency maximization (pareto optimum). hence the marxist claim becomes a moral claim at the expense of economic rationality. If, otoh, we assume that capitalism does not work on the "market" principle but a set of social instiutitions designed to keep concentrated surplus in the hands of one social class, then the issue is not moral claim versus economic rationality anymore, but one moral claim versus another moral claim. Moreover, "bourgeois" moral claim looses its justification as "superior rationality", whereas "marxist" moral claim can still be rationally justified on the grounds of "property rights" which bourgeoisie accept as valid -- i.e. producers deserving to control what they produce.
wojtek