 Take the last of these assorted empirical claims attributed to Marx – the comparative verdict about the extent or intensity of systematic forms of alienation in capitalist societies. Its plausibility is scarcely incontrovertible given the amount of sheer productive drudgery, and worse, in pre-capitalist societies. Nor is it obvious how one might attempt to substantiate the empirical dimensions of the claim. The empirical difficulties of measuring subjective alienation look considerable enough (especially given the limitations of historical data), but alienation for Marx is fundamentally about the frustration of objective human potentials, those separations that prevent self-realisation, perhaps especially self-realisation in work. One suggestion, made in this context, is that the scale of alienation in a particular society might be indicated by the gap between the liberating potential of human productive powers, on the one hand, and the extent to which that potential is reflected in the lives actually lived by producers, on the other (Wood 2004: 44–48). Whatever the appeal of that suggestion, the social scientific details of how one might actually apply that kind of measure in particular historical cases remain unclear.