Modelling the past to predict the future

<span>Photograph: Alamy</span>
Photograph: Alamy

Laura Spinney’s important, excellent long read (Calculating the future, 12 November) draws attention to the developments in quantitative approaches to history pioneered by Jack Goldstone and Peter Turchin, including the journal Cliodynamics, and their predictive possibilities. She could have mentioned the predictive success of Turchin’s quantitative approach (including modelling the rise of popular unrest when average wages lag behind GDP growth per head, meaning rising inequality) regarding the rise of Donald Trump and of support for Brexit.

My article in the July issue of Cliodynamics emphasises the neglect of inequality as a factor in ancient state collapse and the flaws in many quantitative models of modern collapse. In my book Why Did Ancient States Collapse? (September 2019, Archaeopress) I stress the inadequacy of monocausal explanations of collapse and the need for multicausal dynamic models where several factors interact. Common factors running through collapses in ancient Egypt, the western Roman empire and the Maya include: huge inequality, erosion of a sense of common social purpose and cohesion, elites focused on self-enrichment, disputes among the elites, and neglect of key infrastructures, especially water management, economic and fiscal mismanagement; the effects of external factors such as natural disaster and invasion were often exacerbated by internal political, economic and fiscal incompetence. Remind you of anywhere?
Malcolm Levitt

• I was fascinated by Laura Spinney’s engaging article which explored the work of Peter Turchin, who has developed mathematical principles to understand and predict the dynamics of history. Turchin has named this new discipline cliodynamics. Perhaps he should have named it psychohistory though – the name that Isaac Asimov gave to what seems to be a very similar concept in his Foundation series of novels, the first of which was published in 1951.
Robert Bolton
Hullavington, Wiltshire

• Join the debate – email

• Read more Guardian letters – click here to visit

• Do you have a photo you’d like to share with Guardian readers? Click here to upload it and we’ll publish the best submissions in the letters spread of our print edition