The Invention of Invention

This paper models an industrial revolution as a qualitative transition from a world where innovation is infrequent and haphazard to one where it is continuous and systematic. Pre-industrial innovation is treated as a social process where an individual's effectiveness as an innovator depends on the skills of other individuals in his social network. As technology improves, individuals invest more time in learning through social contact. This gradual increase in linkage formation leads to a sudden change in the size of knowledge networks from small, isolated clusters, to a large connected cluster spanning most of the economy, causing a sudden increase in the effectiveness of innovation - an industrial revolution. The predicted sequence of typical innovators - from gifted amateurs, to lucky amateurs, to professionals - is consistent with empirical evidence.Industrial revolution, social networks, innovation

Technological Progress under Learning by Imitation

We analyse technological progress when knowledge has a large tacit component so that transmission of knowledge takes place through direct personal imitation. It is shown that the rate of technological progress depends on the number of innovators in the same knowledge network. Assuming the diffusion of knowledge to mirror the geographical pattern of trade - the greater the trade between two sites, the greater the probability that technical knowledge flows between them - we show that a gradual expansion of trade causes a sudden rise in the rate of technological progress.

Developing Rotten Institutions

This paper models corruption as optimal parasitism in organizations where teams of agents are weakly restrained by principals. Each agent takes on part of the role of principal, choosing how much to invest in policing to repress corruption in others and how rapaciously to act when unpoliced opportunities arise. This simple model incorporates most of the factors stressed in empirical analyses of corruption, and gives rise to a wide variety of equilibria. Allow income to co-evolve with corruption, we show how adding corruption to a textbook exogenous growth model leads to a Lucas paradox. When income and corruption affect each other sufficiently strongly, economies converge to two corner equilibria despite diminishing returns to capital: a rich, clean corner and a poor, corrupt one; a pattern that appears to characterize international data.

The Economic Impact of the Little Ice Age

We investigate by how much the Little Ice Age reduced the harvests on which pre-industrial Europeans relied for survival. We find that weather strongly affected crop yields, but can find little evidence that western Europe experienced long swings or structural breaks in climate. Instead, annual summer temperature reconstructions between the fourteenth and twentieth centuries behave as almost independent draws from a distribution with a constant mean but time varying volatility; while winter temperatures behave similarly until the late nineteenth century when they rise markedly, consistent with anthropogenic global warming. Our results suggest that the existing consensus about a Little Ice Age in western Europe stems from a Slutsky effect, where the standard climatological practice of smoothing data prior to analysis induces spurious cyclicality in uncorrelated data.

Living Standards and Mortality since the Middle Ages

Existing studies find little connection between living standards and mortality in England, but go back only to the sixteenth century. Using new data on inheritances, we extend estimates of mortality back to the mid-thirteenth century and find, by contrast, that deaths from unfree tenants to the nobility were strongly affected by harvests. Looking at a large sample of parishes after 1540, we find that the positive check had weakened considerably by 1650 even though real wages were falling, but persisted in London for another century despite its higher wages. In both cases the disappearance of the positive check coincided with the introduction of systematic poor relief, suggesting that government action played a role in breaking the link between harvest failure and mass mortality.economic growth, economic history, Malthus, demography

The Preventive Check in Medieval and Pre-industrial England

England’s post-Reformation demographic regime has been characterized as ‘low pressure’. Yet the evidence hitherto for the presence of a preventive check, defined as the short-run response of marriage and births to variations in living standards, is rather weak. New evidence in this paper strengthens the case for the preventive check in both medieval and early modern England. We invoke manorial data to argue the case for a preventive check on marriages in the middle ages. Our analysis of the post-1540 period, based on parish-level rather than aggregate data, finds evidence for a preventive check on marriages and births.Malthus, demography, preventive check