Marx uses the terms "capital" and "capitalist." He refers to "the capitalist mode of production." According to Moise Postone, Marx doesn't use the word "capitalism" anywhere. Postone argues (and I agree) that Marx's critique is not that the system is based on capital but that it is based on domination disguised as exchange. Marx locates the domination and the disguise in the abstract value form of labour.
One may think that making a distinction between capitalism and the capitalist mode of production is splitting hairs. However, fundamental to Marx's method of analysis is a concern to see through the ubiquitous personifications of things and reifications of social relationships that pervade our conceptions of social life. As the personification of capital, the capitalist is crucial to the capitalist mode of production. "Capitalism" implies dispensing with the personification, or establishing some mechanism in its place. Let's say that mechanism involves channeling pension funds into equity markets, upholding shareholder value, issuing stock options to top management and employing sophisticated computer models to forecast earnings. Whether or not such a system is viable and whether it is an improvement or a degeneration, it is not the system that Marx analyzed. To use an arcane bit of Marxian terminology, the latter system involves the real subsumption of capital to capital, in essence the "proletarianization of dead labour". Such compounding of a relationship can be regarded as its ironic or sentimental moment -- writing about writing, being in love with love. As Karl Kraus wrote, "sentimental irony is a dog that bays at the moon while pissing on graves." Would it not be more enlightening to regard sentimental irony, not "capitalism" as the "quintessential property of our economic system"? Keith Hudson wrote, > As I read it, however, I couldn't help think what an unfortunate legacy > Marx has left us. His massive work, 'Das Kapital', has given us a term > which is used as a battering ram by the opponents of social injustice but > also by others who should know better (such as The Economist) as being the > quintessential property of our economic system.