Induced population growth and induced technological progress: Their interaction in the accelerating stage

A simple model of Malthusian population growth combined with population‐induced technological progress generates accelerating growth. The model may be relevant for a first stage of growth in which natural resource limitations can be overcome through technological progress; it is not applicable to a later stage in which resource constraints are more resistant. Parameter values are roughly inferred from historical experience. Exogenously more rapid population growth initially depresses income, perhaps for up to several centuries, then raises it without limit. More rapid population growth is desirable only when the social discount rate is less than the ratio of the parameters for induced technical progress and static diminishing returns. Imposed population fluctuations cause inverse movements in incomes, so that induced progress is very difficult to detect empirically even for population fluctuations up to 500 years.

Key words:

• Malthusian model
• population growth
• technological progress
• population fluctuations
• income

Notes

This research was supported by NICHD grant number HD18107, and by Grant 86–6–16 from the Alfred P. Sloan Foundation. Shripad Tuljapurkar, Kenneth Wachter and three referees made helpful comments on an earlier draft.