He cites the work of the economist Steven Levitt and the sociologist Sudhir Venkatesh in understanding drug gangs. "With a constant supply of new low-level drug sellers entering the market and ready to be exploited, drug lords can become increasingly rich without needing to distribute their wealth towards the bottom," he writes. "You have an expanding mass of rank-and-file 'outsiders' ready to forgo income for future wealth, and a small core of 'insiders' securing incomes largely at the expense of the mass. We can call it a winner-take-all market.

Then he turns to academe and finds very similar conditions. "The academic job market is structured in many respects like a drug gang, with an expanding mass of outsiders and a shrinking core of insiders. Even if the probability that you might get shot in academia is relatively small (unless you mark student papers very harshly), one can observe similar dynamics," he writes. "Academia is only a somewhat extreme example of this trend, but it affects labor markets virtually everywhere.... Academic systems more or less everywhere rely at least to some extent on the existence of a supply of 'outsiders' ready to forgo wages and employment security in exchange for the prospect of uncertain security, prestige, freedom and reasonably high salaries that tenured positions entail."

While exact structures of academic hiring vary from country to country, Afonso makes the case that this theory applies in Britain, Germany and the United States, among other countries.

"So what you have is an increasing number of brilliant Ph.D. graduates arriving every year into the market hoping to secure a permanent position as a professor and enjoying freedom and high salaries, a bit like the rank-and-file drug dealer hoping to become a drug lord," he explains. "Because of the increasing inflow of potential outsiders ready to accept this kind of working conditions, this allows insiders to outsource a number of their tasks onto them, especially teaching, in a context where there are increasing pressures for research and publishing. The result is that the core is shrinking, the periphery is expanding, and the core is increasingly dependent on the periphery. In many countries, universities rely to an increasing extent on an 'industrial reserve army' of academics working on casual contracts because of this system of incentives."