I was going to let the demise of Muammar Gaddafi pass without comment—after all, what does the murder of this tyrant have to do with science, right? But a bizarre essay in The New York Times on October 26, "Dictators Get the Death They Deserve," by the historian Simon Windbag—I mean Sebag—Montefiore, has pushed my big red rant button.

Montefiore argued that, although "Western leaders and intellectuals find Colonel Gaddafi's lynching distasteful," there are "sound political reasons for the public culling of the self-proclaimed king of kings." He contends that "as long as the tyrant lives, he reigns and terrorizes…Only death can end both the spell to bewitch and the prerogative to dominate." Montefiore recounted in gleeful, gory detail the violent ends of all manner of tyrants, from the Byzantine emperor Andronicus, who was "beaten and dismembered, his hair and teeth pulled out by a mob," to the pro-Soviet Afghan president Najibullah, who was "castrated, dragged through the streets and hanged."

So, hooray for tit-for-tat vengeance, eh? I wonder if Montefiore is titillated by reports that Libyan rebels have been massacring captured pro-Gaddafi soldiers and even civilians suspected of supporting him. In September, Amnesty International accused both pro-Gaddafi and anti-Gaddafi forces of war crimes. Amnesty International urged Libya's new leaders to "make a complete break with the abuses of the past four decades and set new standards of accountability by putting human rights at the centre of their agenda.”

Yes, of course, Gaddafi and his minions committed atrocities. They're the bad guys. That's why NATO, including the U.S., provided armed assistance to the Libyan rebels. The rebels are supposed to be the good guys, meaning that they should respect, at the very least, laws prohibiting killing of prisoners and civilians. How else can Libya hope to transcend its brutal, traumatic past and create a peaceful, prosperous future?

On the other hand, the U.S., whose leaders love to lecture other nations on their immoral behavior, has not exactly renounced violence. The U.S. maintains a worldwide military presence, paid for—in spite of our economic woes—with a budget almost as great as the military spending of all other nations combined. We are fighting wars in two nations and carrying out assassinations in others, in defiance of international law. We are the world's biggest arms dealers, and we supply armed assistance to non-American warriors, including, since last spring, the Libyan rebels. The rebels captured Gaddafi after a U.S. Predator drone and NATO plane bombed his convoy, which was fleeing the city of Surt. Is there really a difference, morally, between blowing Gaddafi to bits with a Predator and shooting him in the head?

To my mind, the major challenge facing humanity—even greater than finding cheap, clean sources of energy—is ending militarism as a means of resolving disputes. Recently, we've been headed in the right direction. Since World War II, the frequency and lethality of wars has declined, as the political scientist Joshua Goldstein documents in his upbeat new book Winning the War on War: The Decline of Armed Conflict Worldwide (Dutton Adult, 2011), which has the same basic theme as Steven Pinker's The Angels of Our Better Nature: Why Violence Has Declined (Viking Adult, 2011). But if this decline is to continue, the U.S. must work harder to find nonmilitary solutions to threats—and even attacks—against Americans and others.

Goldstein has a much more positive view than I do of the armed intervention of the U.S. and NATO in Libya. Goldstein wrote his blog: "The humanitarian intervention in Libya finally got it right after a number of flawed interventions over the past twenty years. Unlike Kosovo, the Western powers intervened with backing from the UN Security Council—the world's unique source of real legitimacy in such actions. Unlike Somalia, they stayed the course when things took a while to succeed. Unlike Bosnia, they did not try to stay neutral between bad guys and good guys. Unlike Iraq, they supported local rebels with air power rather than invade and occupy. Unlike Rwanda, the international community did not stand by and allow a mass atrocity event to occur (it was hours away in Benghazi when NATO took action). Lessons learned, and applied."

I appreciate the moral logic of Goldstein's analysis. It would have been awfully hard for the U.S. and other nations to stand by and watch Gaddafi slaughter those who called for his ouster last spring. In some cases, humanitarian interventions seem morally inescapable. I just wish we had tried harder to find other, less violent measures to protect Libyans, because I fear that our intervention may incite further violence in Libya and elsewhere. Already, Syrians opposing the regime of Bashar al-Assad are clamoring for NATO's bombers to help them.

On October 25, The New York Times reported that rebel forces in Surt had apparently executed dozens of people—including government officials, loyalist fighters and civilians, some of whose hands were bound by plastic ties—in "one of the worst massacres of the eight-month conflict." The Times quoted a doctor warning that the killings, if they are not investigated and punished, might lead to counter-reprisals.

The desire for vengeance is deep-rooted, as the evolutionary biologist David Barash and psychiatrist Judith Lipton, who are married, note in their fascinating new book Payback: Why We Retaliate, Redirect Aggression, and Take Revenge (Oxford University Press, 2011). Not just humans but many animals retaliate against those who threaten or harm them, Barash and Lipton point out. We also engage in "redirected aggression," lashing out against innocent bystanders. The classic example is the man who, after being yelled at by his boss, goes home and whacks his wife or kid. Another example is the U.S., which, after being attacked by al Qaeda 10 years ago, invaded Iraq, which had nothing to do with 9/11. If we don't try harder to break these cycles of violence, we will never escape war's grip once and for all.

Photo of Gaddafi courtesy of Wikimedia Commons and Aljazeera.net.