The Collapse of Complex Societies by Joseph A. Tainter is a well-researched and erudite account of why ancient complex societies collapsed. Tainter makes a solid point that increasing complexity is a natural and rational response as a society grows. The author refreshingly argues that collapse is not an unmitigated disaster but a rational reversal to a society of lower complexity and smaller units when the overhead of the complex society no longer offers a benefit larger than its cost.
Tainter correctly identified the mechanism of diminishing returns as the main reason why a society runs up against its limits. However, instead of growth and complexity leveling off as the marginal benefits decrease, he argues that societies continue to increase in complexity even when the cost exceeds the benefit. He rightly debunks insufficient leadership as a reason for collapse but, at the same time, assumes that a society would sleepwalk into increasing bureaucracy beyond what makes economic sense.
He makes a much stronger argument about societal fragility. A society with a resource surplus can respond to various calamities, but as complexity increases, it will eventually consume all available resources, leaving no buffer to handle situations that were previously manageable.
Unless you are a scholar of archeology, you do not have to read the entire book. John Danaher has written a great summary here.
