So just how are these numbers determined? Bounty amounts are based on the perceived threat a given terrorist poses to U.S. people or property, an official with the Bureau of Diplomatic Security told me. The secretary of state sets the price and can raise or lower it if, say, a terrorist gets promoted or demoted within an organization, or information emerges about planned attacks. If there’s a more precise formula, the official didn’t say.

The bureau’s explanation suggests the process is more art than science, but some believe bounties could be better priced. Alex Tabarrok, an economics professor at George Mason University, thinks the sums should be higher. In a post last week on Marginal Revolution, he noted that his research on bounties in the U.S. criminal-justice context had convinced him that bounty hunters are “an effective part of the American justice system.” But the bounty hunters he studied get paid to capture criminal defendants who have fled. “For international terrorists,” Tabarrok told me, “my thinking is mostly that these are for information acquisition—to tell us where [terrorists] are.” The ideal case is a terrorist insider who betrays the organization to get a reward. “So bin Laden, you know, kicks his cook one day, and the cook says, ‘I’ve had enough of this. Take this job and shove it.’”

But what influences the price at which this hypothetical cook will give up his boss? Is $25 million enough? In addition to factors like the risk a given terrorist poses to the United States, Tabarrok argued that the number should take into account the opportunity costs of pursuing strategies other than offering bounties. Calculating bounties this way would yield much higher amounts than current figures.

“We could’ve put a bounty on bin Laden’s head in 2001 of, let’s say, $500 million,” he said. “Instead we chose, no, we’re going to spend something like a trillion dollars invading Afghanistan, and then we’re going to be there for now over 10 years, and this is going to cost so many U.S. lives.” Of course, it’s impossible to know whether the offer of a higher bounty could have netted bin Laden right after the 9/11 attacks and thereby prevented the invasion of Afghanistan. According to the terms of the ultimatum that George W. Bush delivered to the Taliban in September 2001—“they will hand over the terrorists or they will share in their fate”—invasion wasn’t a foregone conclusion. By his own account, Robert Grenier, the CIA station chief in Islamabad at the time, was scrambling to forestall the invasion right up until the first American airstrikes started. In the counterfactual where an al-Qaeda insider betrayed bin Laden for money and the U.S. didn’t invade Afghanistan, Tabarrok said, “maybe $500 million doesn’t look so expensive” compared with what actually occurred.