TLDR: Joseph Tainter argues that the root cause of civilizational collapse is because of
over-investment into and declining marginal returns on complexity. Societies invest in complexity to solve their problems and typically need to expend ever more organizational and physical energy to maintain that level of complexity; eventually, this expenditure undermines their material base, opens up a large potential gap where they could reap the exact same benefits but at a lower level of complexity (and cost), and the likelihood of collapse converges to one.
You can read excellent summaries of the book by
Ugo Bardi, and
Joseph Tainter himself.
IntroductionRuins and relics of long dead civilizations, now overtaken by vines of verdant chaos, or buried under the shifting sands of time, hold a certain morbid fascination for us - these once great, hubristic and monumental societies that flourished and then collapsed, leaving only ruins and legends in their wake. We cannot help entertaining thoughts about the sustainability of own, global, industrial civilization; the "possibility that a civilization should die doubles our own mortality".
What is collapse? Tainter starts off by defining collapse - when an empire, chiefdom or tribe experiences a "significant loss of an established level of socio-political complexity", manifesting itself in decreases in vertical stratification, occupational specialization, regimentation, centralization, information and trade flows, literacy, artistic achievement, territorial extent and investment in the "epiphenomena of civilization" (palaces, granaries, temples, etc). He summarizes a large number of historic collapses - Harappa, the Western Chou, Mesopotamia, Egypt, Mycenaean Greece, the Roman Empire and different American cultures.
Comment: For an excellent rundown of Monsanto's interests in marijuana, see the two part: