Joseph Tainter is a U.S. historian whose best-known work is The Collapse of Complex Societies. This 1988 book examines the collapse of Maya, Chacoan and Roman empires in terms of network theory, energy economics and complexity theory. Tainter argues that societies collapse when their investments in social complexity begin to have diminishing marginal returns.

According to Tainter, societies become more complex in order to solve problems. For Tainter, a complex society's characteristics include a variety of differentiated social and economic roles for its members, reliance on symbolic and abstract communication, a large class of information producers and analysts not involved in primary resource production (among others), all of which are enabled by a substantial energy subsidy.

When a society confronts a problem (in Tainter's terms, a problem means difficulty in gaining access to energy, which is the sine qua non of all human problem solving), it becomes more complex. That is, it adds bureaucracy, or new technology, or a new social class, in order to meet the new needs created by the most recent challenge.

For example, as Roman agricultural output slowly declined and population increased, per-capita energy availability dropped. The Romans "solved" this problem by conquering their neighbours in order to appropriate their energy surpluses (metals, grain, slaves, etc). However, as the Empire grew, the cost of maintaining communications, garrisons, civil government, etc grew to the point where new challenges, such as invasions and crop failures, became unsolvable by the acquisition of more territory. At this point, Roman society fragmented into smaller units.

As societies become more complex, the returns on investments in complexity gradually diminish. Tainter musters statistics about the modern world which suggest that marginal returns on various kinds of investment, such as in energy, education, and technological innovation, are diminishing.

The book concludes with suggestions that the globalised modern world has emerged, in part, as a result of both massive (and unsustainable) fossil fuel subsidies, as well as of the "competitive spiral in which we have allowed ourselves to become trapped." (Tainter, p. 214) Tainter finally states that the modern world will be subject to many of the same stresses—diminishing marginal returns on investments in social complexity—in which brought older societies to ruin:

"A new energy subsidy is necessary if a declining standard of living and a future global collapse are to be averted. A more abundant form of energy might not reverse the declining marginal return on investment in complexity, but it would make it more possible to finance that investment." (Tainter, p. 215)

References

• Tainter, Joseph A. (1990). The Collapse of Complex Societies (1st paperback ed.). Cambridge: Cambridge University Press. ISBN 0-521-38673-X.