War and Peace and War
Peter Turchin, 2006 — cycles.
The founding public text of cliodynamics — history treated as a data science. Turchin shows empires being forged on "meta-ethnic frontiers" where external pressure welds cooperation, then dying of elite overproduction as internal competition dissolves it. Secular cycles of two to three centuries, punctuated by ~50-year violence spikes, appear in Rome, France, Russia and the US alike.
Why the engine keeps this on the shelf
Turchin published a dated, falsifiable macro-historical forecast in a refereed venue and let it be graded a decade later; that is the exact standard the Calibration Ledger holds itself to, which is why his elite-overproduction series feeds the engine's polarization component.
The record
- Published in 2006, it is the founding popular statement of cliodynamics — the quantitative history programme Turchin named and built.
- In a February 2010 letter to Nature, Turchin wrote that the coming decade was likely to bring growing instability to the United States and western Europe; because instability events had been declining before 2010, this was a forecast trend reversal, not an extrapolation.
- A retrospective assessment published in PLOS ONE in 2020 found that measured instability events — anti-government demonstrations and riots — had in fact risen sharply across 2010–2020, and the accepted paper needed a postscript for the pandemic and the summer that followed.
- He extended the argument in Ages of Discord (2016) and End Times (2023), reporting that in roughly three-quarters of past societies showing the same pattern of elite overproduction and popular immiseration, the outcome was some form of convulsive state breakdown.
Marked passages
The next decade is likely to be a period of growing instability in the United States and western Europe.
From his February 2010 letter to Nature — a macro-historical forecast published in advance, with a date. It resolved correct. This is the standard our Calibration Ledger holds itself to.
The core claims
- Empires are welded together on hard frontiers where outside pressure makes cooperation cheaper than defection, and they come apart from the inside when the elite class grows faster than the number of elite positions available to it.
- Inequality is a stability variable, not only a fairness one: a wealth pump that moves income upward immiserates the base and overproduces credentialed claimants at the same time, and the two curves cross about a generation before the trouble arrives.
Then and now
The 2025–26 US law-school cycle produced 82,484 applicants, up about 8% and the highest total since 2010, following an 18% jump the previous cycle — credential-seeking outrunning the seats, which is elite overproduction seen from below. Source: LSAC applicant volume data, 2025–26 cycle
CSIS puts attacks and plots against US government figures at a 30-year high in 2025, and records 2025 as the first year in more than three decades in which left-wing attacks outnumbered far-right ones. Source: CSIS Transnational Threats Project, 2025
European military spending rose 14% in 2025 and Germany, at $114 billion, became the world's fourth-largest spender — external pressure re-welding cooperation on a frontier, the other half of Turchin's mechanism. Source: SIPRI Fact Sheet, Apr 2026
More on this shelf
The shelf exists because the engine reads it. See the Core, the projections, the sealed ledger, or all 81 texts.