In Russia, Vladimir V. Putin needs his circle of handpicked oligarchs; in Iran, the Revolutionary Guards and its allies in the business world protect the regime’s power; Viktor Orban transformed Hungary into an “elected autocracy” with the help of a few crucial judges, political enforcers and friendly tycoons. But to actually carry out the dirty work of consolidating and maintaining power, such leaders rely on help from a far greater number of lower- and midlevel people: military officers, secret police and bureaucrats.

Yet until recently, researchers paid little attention to how leaders convince and recruit ground-level workers to go along with their demands. The incentives for elites to stay loyal have been studied extensively, but the rank and file have remained something of a black box. In the absence of real data, researchers have tended to assume that they cooperate because of ideological extremism, fear of persecution or some combination of the two.

New research, drawing on an extraordinary data set from Argentina’s Dirty War in the 1970s and ’80s, suggests a very different explanation. It turns out that the kinds of career pressures familiar to employees everywhere — the desire to revive a stalled career or obtain a minor promotion — can be enough to incentivize lower- and midlevel officials to violate professional obligations, fundamental norms and even basic morality. The people who make those decisions, the research suggests, are neither extremists nor victims. They are often just middling workers looking for a way to get ahead.

...Their in-depth study of Argentina’s military during that country’s era of coups and forced disappearances found that low performers — whom they refer to as “career-pressured” individuals — filled the ranks of the secret police. That service allowed them to “detour” around the ordinary military hierarchy, the book shows, achieving promotions and career success they could never have managed otherwise.