L'impact des changements démographiques sur la croissance et le marché du travail : faits, théories et incertitudes

This paper proposes a short survey on macro-economic consequences of demographic change. The nature and magnitude of demographic changes expected for the first half of the century is first reviewed, with a special emphasis on factors explaining the irreversibility of the aging process. Consequences of these changes are then examined in the context of standard growth models. The conclusion of the basic Solow model remains malthusian in the sense that population growth reduces income per capita, due to capital dilution effects. Lower or even negative population growth rates should, therefore, have a positive (albeit moderate) impact on the standard of living. This result is not consistent with historical evidence. Two approaches are available for the obtention of positive effects of population growth. One is provided by some models of endogenous growth : these models are interesting, but lead to the opposite result that more population growth is always desirable in the long run. A more balanced view is provided by overlapping generation models according to which intermediate rates of population growth are more likely to maximize income per capita. A last section is devoted to analyzing demographic impacts on the labour market: demographic effects appear to be of second order, and the impact of aging or population decline can be positive or negative, depending on the relative importance of the various determinants of demand and wages.