An Escape from the Malthus Rectangle? Poverty, and Conversion Efficiency (Distinguishedl Lecture)

Malthus (1798, 1803, 1824) wrote during the world's firstperiod of sustained and widespread growth in real income per person: the"Northern" agro-industrial revolution of 1740-1970. When he wrote, itwas widely believed that not only growth, but also poverty reduction,depended substantially on what he called "schemes of improvement".Malthus's central claim is that these could not reduce poverty in thelong run, unless fertility declined. This, he believed, was because anyshort-run success of "schemes of improvement" in reducing poverty wouldincrease the rate of population growth among the poor. This would raisethe supply of labour and the demand for food. Owing to diminishingmarginal returns to extra hectares-plus-persons as new, inferior landwas brought into cultivation, "the proportion between the price oflabour and the price of provisions" would then fall, thus returning thepoor to poverty. Unless fertility fell, the long-term well-being of thepoor could not improve much. Being largely dependent on the real wage,it was boxed in by the Malthus rectangle (Figure 1) of population,labour supply, land, and food, and the interactions amongthem.