Probably one of the few places in Marx where this can be found in a naked form is in the preface to Contribution to a Critique of Political Economy, where he writes: "In the social production of their existence, men inevitably enter Into definite relations, which are independent of their will, namely relations of production appropriate to a given stage in the development of their material forces of production. The totality of these relations of production constitutes the economic structure of society, the real foundation, on which arises a legal and political superstructure and to which correspond definite forms of social consciousness. The mode of production of material life conditions the general process of social, political and intellectual life. It is not the consciousness of men that determines their existence, but their social existence that determines their consciousness." But against this, you have an enormous amount of written material that transcends this model, most especially in the 18th Brumaire where Marx considers the phenomenon of Bonapartism, a ruling class government acting against its own interests, a phenomenon Doug has expressed some puzzlement over from time to time: "If by its clamour for tranquillity the parliamentary Party of Order.. committed itself to quiescence, if it declared the political rule of the bourgeoisie to be incompatible with the safety and stability of the bourgeoisie, by destroying with its own hands in the struggle against all other classes of society the conditions for its own regime, the parliamentary regime, then the extra-parliamentary mass of the bourgeoisie, on the other hand, by its servility toward the President, by its vilification of parliament, by the brutal maltreatment of its own press, invited Bonaparte to suppress and annihilate its speaking and writing section, its politicians and its literati, its platform and its press, in order that it might then be able to pursue its private affairs with full confidence in the protection of a strong and unrestricted government. It declared unequivocally that it longed to get rid of its own political rule in order to get rid of the troubles and dangers of ruling." When you really get down to it, the base/superstructure model is nearly useless when you are doing sophisticated class analysis of societies past or present. Right now I am taking a close look at the late 17th and early 18th century in order to understand what Leibniz stood for. David Harvey, unfortunately, has little interest in seeing Leibniz in contrast and just holds him up as a expert on "relationism". Now we all know that Leibniz is the father of German Enlightenment thought and strongly influenced Kant. Furthermore, we have all been introduced to the idea that the Enlightenment was the superstructure of the changing base that capitalism was producing. At least that's the view you might get in a new member's class in some Marxist sect. However, reality is much more complex. Leibniz was actually devoted to monarchic rule and much of his philosophy is an attempt to wed justification for feudal structures with new investigations taking place in science that would ultimately threaten feudal modes of thought. The monarchies of the 17th and 18th century represented attempts by feudal society to bring a halt to the sort of social disintegration religious wars, like the 30 years war, had created. So the King became in effect a Bonapartist figure, in the feudal sense, who rose above the princes and dukes who had been more directly involved with warmaking. What gets complicated is figuring out to what extent the absolutist regimes were harbingers of the capitalist system. Perry Anderson argues against this position in "Lineages of the Absolutist State." Leibniz was in the thick of all these battles and his philosophy, scientific investigations and theology were all connected to his political life. His fights with Newton and Clarke around questions of whether god ruled through will or through reason were closely related to rivalries inside the Hanover court, with the former two advocating a Tory position and Leibniz's backers advocating Whiggery. At any rate, trying to use a simple base/superstructure model to explain all this is like trying to explain dynamic processes in nature without calculus. As Jim Devine pointed out, we are interested in Process. Keeping in mind that Stalinists and Social Democrats have cheapened the term dialectical materialism, there is still something of value here. Dialectics refers to change, especially of a contradictory nature, while materialism refers to the fact that you are dealing with objective reality, such as land ownership, money, technology, weapons, natural resources and factories. Louis Proyect (http://www.panix.com/~lnp3/marxism.html)