The metaphor used by Marx and Engels to characterize the relation between the economic organization of society, which is its base, and the political, legal, and cultural organization and social consciousness of a society, which is the superstructure. The sum total of the relations of production of material life ‘conditions the social, political, and intellectual life process in general’ (Marx, Preface to A Contribution to the Critique of Political Economy). The way in which the base determines the superstructure has been the object of much debate, with writers from Engels onwards concerned to distance themselves from the reductionist and mechanistic implications that the metaphor might suggest. It has also been pointed out that relationships involved in production are not merely economic, but involve political and ideological relations. The view that all causal power is centred in the base, with everything in the superstructure merely epiphenomenal, is sometimes called economism. The problems are strikingly similar to those that arise when the mental is regarded as supervenient upon the physical, and it is then disputed whether this takes all causal power away from mental properties.