The brutal math and mechanics of revolutions. This book focuses on events in the pre-industrial era, but the basic principles are still broadly applicable today. Earlier revolutions just made the dynamics more stark because they played out in societies that had fewer resources, and thus lived closer to the edge of privation.
The major revolutions discussed here (the Puritan Revolution in 17th century England, the French Revolution of 1789, the Ottoman Crisis in Asia Minor, and the Ming-Qing Transition in China) all followed the same pattern: Revolution started with demography.
Until relatively recent times, human populations grew slowly, and often fell during epidemics. That's largely because rates of mortality among young children were staggeringly high across all levels of society, typically from infectious disease. (For just one -- admittedly extreme -- example, consider Michel de Montaigne, one of the wealthiest and most prominent men in 16th century France: He lost 5 of his 6 children in infancy.) The horrific death rate among the youngest generally kept populations from rising much, if at all. But a slight let-up in disease burden might allow more children to survive, creating a youth bulge. Within a few years, an unusually large number of young people would be looking for work within an inelastic agrarian economy (many being drawn to cities, where they formed a potentially combustible mass). Food prices would inevitably rise as a larger population pressed down on the low crop yields of pre-modern agriculture.
Then the revolutionary spiral would set in. Rulers were forced to pay more to feed their armies (depleting the royal coffers), while the poorest were pushed to the edge of starvation. Rulers then sought to address their fiscal shortfall through higher taxes on landowners, who formed the traditional elites of their societies. This angered the elites (who passed the higher taxes down to their already burdened tenants and workers).
Even with sharp tax increases, the land base could not provide enough revenue. So rulers turned to selling noble titles and lucrative government offices. The buyers typically were merchants who had grown wealthy on trade and manufacture. The influx of nouveau nobles and office holders further angered the old elites, who saw their privileges being eroded. Disgruntled elites eventually split among themselves, with some openly rebelling against their rulers and whipping up violent revolt among the poorer classes, who had ample grievances to fuel their anger. (Revolutionaries were particularly likely to be younger sons of the elite classes who, in less straitened times, might have been able to find positions that suited them.)
Interestingly, all these pre-industrial societies might have been able to avoid revolution if they had broadened their tax bases, because trade and manufacture were generating enough income to provide adequate revenue. But they were unable to adjust away from their traditional emphasis on land taxation -- probably because they could not fully grasp what was happening. Economics and demography barely existed as fields of study at the time. It's only with the painstaking work of modern historians, digging through old records and carefully piecing the story together, that we now have a clearer picture.
How about the role of ideology in revolutions? Grand slogans like "liberté, egalité, fraternité" get all the attention, but they're as much a consequence as a cause of revolution. The initial rebellions were often limited in their aims. But as the old order fell and revolutionaries gained power, they vied among themselves for leadership -- becoming more radical as a way to gain further support among the masses.
Comparing the Puritan and French Revolutions throws an interesting light on the function of ideology: The Puritans, fired by religious zeal, aimed to create a community of saints. The French revolutionaries proclaimed secular values and attacked the church. But both societies eventually reverted largely to their pre-revolutionary status, with restoration of their old monarchical families to the throne. Nonetheless, the long-term impact of their revolutionary ideologies lingered, forming part of their national mythology.
Modern society has attenuated the impact of poverty and inequality. Outright food shortages, for instance, usually occur only with wartime blockades or extreme government mismanagement. But the tendency for elites to suck up most of their society's wealth seems to be a constant of human history. (For more on this, see _The Great Leveler: Violence and the History of Inequality from the Stone Age to the Twenty-First Century_ by Walter Scheidel.) And the dynamics of revolution are much the same today as they were in 1640. Those at the bottom generally lack the resources to organize a rebellion on their own. That still takes elite encouragement (and is helped along greatly if the relatively prosperous middle classes join the fight). As the author notes, the Iranian Revolution of 1979 and the Arab Revolutions of 2010-11 closely followed the pattern outlined in this study.
Goldstone's book has become a classic that is now widely studied. Are some who've learned from it now trying to turn Russia's elites against Vladimir Putin by imposing economic sanctions that damage the country's oligarchs?