Demographic Metabolism: A Predictive Theory of Socioeconomic Change

this essay introduces a general theory of how societies change as a consequence of the changing composition of their members with respect to certain relevant and measurable characteristics. these characteristics can either change over the life course of individuals or from one generation to the next. while the former changes can be analytically identified and described by certain ageand duration-specific transition schedules, the latter changes resulting from cohort replacement can be modeled and projected using standard models of population dynamics. Building on earlier qualitative work by Karl mannheim and norman ryder, this new theory applies the quantitative tools of multi-dimensional mathematical demography to forecast the future composition of a population according to relevant characteristics. in the case of persistent characteristics (such as highest educational attainment) that typically do not change from young adulthood until the end of life, quantitative predictions about the distributions of such characteristics in the population can readily be made for several decades into the future. For other characteristics that tend to change over the life course (such as labor force participation), standard age/durationspecific patterns can be assumed. Hence, unlike other models that are called “theories” but cannot be used to make explicit quantitative statements about the future, this theory of socioeconomic change can make such statements in a way that can potentially be falsified. it can therefore be called a theory with predictive power according to Karl Popper’s criteria (Popper 1959). this is a theory predicting aggregate-level change rather than individual behavior. it is a macro-level theory focusing on the changing composition of a population and hence has no micro-level analogue. it can be called a “demographic” theory of socioeconomic change, implying that its inspiration and approach are demographic though its purpose is not. it is not primarily intended to explain and forecast demographic variables (such as population size, birth and death rates, migration, and the like); rather the goal is to predict