Given the ongoing decay of our institutions and their utter failure to address the climate crisis it is not far fetched to ask whether we are headed for some kind of societal collapse. A highly relevant book is Joseph Tainter’s The Collapse of Complex Societies, published in 1988. I had two key takeaways from reading it.

First, there are way more examples of complex societies collapsing than I was aware of. I was of course familiar with the collapse of the Roman Empire and was also aware of Mayas in the Yucatan (having visited there) but Tainter provides at least a dozen examples, including several societies that I had never heard of before. He also rightfully points out that complexity so far is the historical exception and widespread complexity (meaning the world being dominated by complex societies is a particularly recent phenomenon). So the takeaway here is in part that we really aren’t very deep into the current complexity phase and that the past track record over longer time periods isn’t exactly encouraging.

Second, Tainter proposes a very simple and general mechanism leading to collapse: declining marginal returns to complexity. Over time the benefits of complexity diminish and its costs increase. When that happens societies become prone to collapse from (a) having not enough reserves to deal with shocks and/or (b) parts of society that are bearing a disproportionate share of the cost of complexity resisting. He then analyzes the role of this mechanism in three collapses in some detail, including for the collapse of the Roman Empire. One striking feature of that particular collapse is the massive currency devaluation over hundreds of years that has strong echos in today’s world.

Tainter gives many reasons for why the benefits of complexity decline over time and its cost rise. One that he doesn’t discuss much but that is particularly pertinent to today, is the accretion of laws and regulations. While these are essential tools for maintaining complex societies it is particularly easy to see how over time their benefits decline and their costs rise when you only ever add laws and regulations but never do a partial or complete rewrite. It is the societal equivalent of the accumulation of technical debt in startups.

Are there ways of avoiding collapse? First, as Tainter points out, quite a few societies don’t collapse but simply go into a long decline and then get taken over by other societies. He thinks that this is a possible scenario for many societies today because they are surrounded by other complex societies (this does, however, leave open the possibility of many societies collapsing at about the same time). Second, Tainter also points to examples of avoiding collapse through a big resource or energy unlock. Deploying solar at massive scale could be such an unlock, as could be fusion if we get it working.

All in all a very worthwhile read combining a ton of history with an analytical framework. I find most historical writing to be replete with ad hoc explanations that don’t sound much more compelling than CNBC talking about why the market went up or down. The Collapse of Complex Societies stands out from that and all the more so coming in at only 215 pages. Highly recommended.