The Collapse of The Roman Empire
One outcome of diminishing returns to complexity is illustrated by the collapse of the Western Roman Empire. As a solar-energy based society which taxed heavily, the empire had little fiscal reserve. When confronted with military crises, Roman Emperors often had to respond by debasing the silver currency (Figure 4.2) and trying to raise new funds. In the third century A.D. constant crises forced the emperors to double the size of the army and increase both the size and complexity of the government. To pay for this, masses of worthless coins were produced, supplies were commandeered from peasants, and the level of taxation was made even more oppressive (up to two-thirds of the net yield after payment of rent). Inflation devastated the economy. Lands and population were surveyed across the empire and assessed for taxes. Communities were held corporately liable for any unpaid amounts. While peasants went hungry or sold their children into slavery, massive fortifications were built, the size of the bureaucracy doubled, provincial administration was made more complex, large subsidies in gold were paid to Germanic tribes, and new imperial cities and courts were established. With rising taxes, marginal lands were abandoned and population declined. Peasants could no longer support large families. To avoid oppressive civic obligations, the wealthy fled from cities to establish self-sufficient rural estates. Ultimately, to escape taxation, peasants voluntarily entered into feudal relationships with these land holders. A few wealthy families came to own much of the land in the western empire, and were able to defy the imperial government. The empire came to sustain itself by consuming its capital resources; producing lands and peasant population (Jones 1964, 1974; Wickham 1984; Tainter 1988, 1994b). The Roman Empire provides history's best-documented example of how increasing complexity to resolve problems leads to higher costs, diminishing returns, alienation of a support population, economic weakness, and collapse. In the end it could no longer afford to solve the problems of its own existence.
Figure 4.2. Debasement of the Roman silver currency, 0-269 A.D. (after Tainter 1994b with modifications). The chart shows grams of silver per denarius (the basic silver coin) from 0 to 237 A.D., and per 1/2 denarius from 238-269 A.D. (when the denarius was replaced by a larger coin tariffed at two denarii).
Population, Resources, and Industrialism
The fate of the Roman Empire is not the unavoidable destiny of complex societies. It is useful to discuss a historical case that turned out quite differently. In one of the most interesting works of economic history, Richard Wilkinson (1973) showed that in late-and post-medieval England, population growth and deforestation stimulated economic development, and were at least partly responsible for the Industrial Revolution. Major increases in population, at around 1300, 1600, and in the late 18th century, led to intensification in agriculture and industry. As forests were cut to provide agricultural land and fuel for a growing population, England's heating, cooking, and manufacturing needs could no longer be met by burning wood. Coal came to be increasingly important, although it was adopted reluctantly. Coal was costlier to obtain and distribute than wood, and restricted in its occurrence. It required a new, costly distribution system. As coal gained importance in the economy the most accessible deposits were depleted. Mines had to be sunk ever deeper, until groundwater came to be a problem. Ultimately, the steam engine was developed and put to use pumping water from mines. With the development of a coal-based economy, a distribution system, and the steam engine, several of the most important technical elements of the Industrial Revolution were in place. Industrialism, that great generator of economic well-being, came in part from steps to counteract the consequences of resource depletion, supposedly a generator of poverty and collapse. Yet it was a system of increasing complexity that did not take long to show diminishing returns in some sectors. This point will be raised again later.
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