You would think that the disappearance of the gravest threat in the history of humanity would bring a sigh of relief among commentators on world affairs. Contrary to expert predictions, there was no invasion of Western Europe by Soviet tanks, no escalation of a crisis in Cuba or Berlin or the Middle East to a nuclear holocaust. The cities of the world were not vaporized; the atmosphere was not poisoned by radioactive fallout or choked with debris that blacked out the sun and sent Homo sapiens the way of the dinosaurs. Not only that, but a reunified Germany did not turn into a fourth reich, democracy did not go the way of monarchy, and the great powers and developed nations did not fall into a third world war but rather a long peace, which keeps getting longer. Surely the experts have been acknowledging the improvements in the world's fortunes from a few decades ago.

Macbeth's self-justifications were feeble -- and his conscience devoured him. Yes, even Iago was a little lamb too. The imagination and the spiritual strength of Shakespeare's evildoers stopped short at a dozen corpses. Because they had no ideology.-- Aleksandr Solzhenitsyn

But no -- the pundits are glummer than ever! In 1989 John Gray foresaw "a return to the classical terrain of history, a terrain of great power rivalries… and irredentist claims and wars." A New York Times editor wrote in 2007 that this return had already taken place: "It did not take long [after 1989] for the gyre to wobble back onto its dependably blood-soaked course, pushed along by fresh gusts of ideological violence and absolutism." The political scientist Stanley Hoffman said that he has been discouraged from teaching his course on international relations because after the end of the Cold War, one heard "about nothing but terrorism, suicide bombings, displaced people, and genocides." The pessimism is bipartisan: in 2007 the conservative writer Norman Podhoretz published a book called World War IV (on "the long struggle against Islamofascism"), while the liberal columnist Frank Rich wrote that the world was "a more dangerous place than ever." If Rich is correct, then the world was more dangerous in 2007 than it was during the two world wars, the Berlin crises of 1949 and 1961, the Cuban Missile Crisis, and all the wars in the Middle East. That's pretty dangerous.

Why the gloom? Partly it's the result of market forces in the punditry business, which favor the Cassandras over the Pollyannas. Partly it arises from human temperament: as David Hume observed, "The humour of blaming the present, and admiring the past, is strongly rooted in human nature, and has an influence even on persons endowed with the profoundest judgment and most extensive learning." But mainly, I think, it comes from the innumeracy of our journalistic and intellectual culture. The journalist Michael Kinsley recently wrote, "It is a crushing disappointment that Boomers entered adulthood with Americans killing and dying halfway around the world, and now, as Boomers reach retirement and beyond, our country is doing the same damned thing." This assumes that 5,000 Americans dying is the same damned thing as 58,000 Americans dying, and that a hundred thousand Iraqis being killed is the same damned thing as several million Vietnamese being killed. If we don't keep an eye on the numbers, the programming policy "If it bleeds it leads" will feed the cognitive shortcut "The more memorable, the more frequent," and we will end up with what has been called a false sense of insecurity.

The first kind of organized violence embraces all the other categories of war, most notably the civil wars and wars between militias, guerrillas, and paramilitaries that plague the developing world. These are the "new wars" or "low-intensity conflicts' that are said to be fueled by "ancient hatreds." Familiar images of African teenagers with Kalashnikovs support the impression that the global burden of war has not declined but has only been displaced from the Northern to the Southern Hemisphere.

This chapter is about three kinds of organized violence that have stoked the new pessimism. They were given short shrift in the preceding chapter, which concentrated on wars among great powers and developed states. The Long Peace has not seen an end to these other kinds of conflict, leaving the impression that the world is "a more dangerous place than ever."

The new wars are thought to be especially destructive to civilians because of the hunger and disease they leave in their wake, which are omitted from most counts of war dead. According to a widely repeated statistic, at the beginning of the 20th century 90 percent of war deaths were suffered by soldiers and 10 percent by civilians, but by the end of the century these proportions had reversed. Horrifying estimates of fatalities from famines and epidemics, rivaling the death toll of the Nazi Holocaust, have been reported in war-torn countries such as the Democratic Republic of the Congo.

The second kind of organized violence I will track is the mass killing of ethnic and political groups. The hundred-year period from which we have recently escaped has been called "the age of genocide" and "a century of genocide." Many commentators have written that ethnic cleansing emerged with modernity, was held at bay by the hegemony of the superpowers, returned with a vengeance with the end of the Cold War, and today is as prevalent as ever.

The third is terrorism. Since the September 11, 2001, attacks on the United States, the fear of terrorism has led to a massive new bureaucracy, two foreign wars, and obsessive discussion in the political arena. The threat of terrorism is said to pose an "existential threat" to the United States, having the capacity to "do away with our way of life" or to end "civilization itself."

Each of these scourges, of course, continues to take a toll in human lives. The question I will ask in this chapter is exactly how big a toll, and whether it has increased or decreased in the past few decades. It's only recently that political scientists have tried to measure these kinds of destruction, and now that they have, they have reached a surprising conclusion: All these kinds of killing are in decline. The decreases are recent enough -- in the past two decades or less -- that we cannot count on them lasting, and in recognition of their tentative nature I will call this development the New Peace. Nonetheless the trends are genuine declines of violence and deserve our careful attention. They are substantial in size, opposite in sign to the conventional wisdom, and suggestive of ways we might identify what went right and do more of it in the future.