Some more quotes from Lefebvre on Marx’s method in Capital. Granted, he does use dialectical a bit too much without describing how and why they are dialectical, but still suggestive I reckon. (Betcha can’t tell I’m re-writing my section on Lefebvre’s interpretation of Marx.)
Capital as a critique of political economy. As a form of praxis: how goods in short supply are distributed amongst groups in equal size, influence, function and place in the social structure. The Sociology of Marx 15
In Capital (1867) Marx worked out his conception of the dialectic still more thoroughly. The categories are abstract, inasmuch as they are elements obtained by the analysis of the actual given content, and inasmuch as they are simple general relations involved in the complex reality. But there can be no pure abstraction. The abstract is also concrete, and the concrete, from a certain point of view, is also abstract. All that exists for us is the concrete abstract. There are two ways in which the economic categories have a concrete, objective reality: historically (as moments of the social reality) and actually (as elements of the social objectivity). And it is with this double reality that the categories are linked together and return dialectically into the total movement of the world.
The study of economic phenomena is not an empirical one, it rests on the dialectical movement of the categories. The basic economic category – exchange-value – is developed and, by an internal movement, gives rise to fresh determinations: abstract labour, money, capital. Each complex determination emerges dialectically from the preceding ones. Each category has a logical and methodological role, it has its place in the explicative whole which leads to the reconstitution of the given concrete totality, the modern world. It also corresponds to an epoch, and the general historical characteristics of the epoch in question – the framework for events and actions – can be deduced by starting from the category essential to it.