Today the vast majority of the world's people do not have to worry about dying in war. Since 1945, wars between great powers and developed states have essentially vanished, and since 1991, wars in the rest of the world have become fewer and less deadly.
But how long will this trend last? Many people have assured me that it must be a momentary respite, and that a Big One is just around the corner.
Maybe they're right. The world has plenty of unknown unknowns, and perhaps some unfathomable cataclysm will wallop us out of the blue. But since by definition we have no idea what the unknown unknowns are, we can't constructively worry about them.
What, then, about the known unknowns? Are certain risk factors numbering our days of relative peace? In my view, most people are worrying about the wrong ones, or are worrying about them for the wrong reasons.
Resource shortages. Will nations go to war over the last dollop of oil, water, or strategic minerals? It's unlikely. First, resource shortages are self-limiting: as a resource becomes scarcer and thus more expensive, technologies for finding and extracting it improve, or substitutes are found. Also, wars are rarely fought over scarce physical resources (unless you subscribe to the unfalsifiable theory that all wars, regardless of stated motives, are really about resources: Vietnam was about tungsten; Iraq was about oil, and so on.) Physical resources can be divided or traded, so compromises are always available; not so for psychological motives such as glory, fear, revenge, or ideology.
Climate change. There are many reasons to worry about climate change, but major war is probably not among them. Most studies have failed to find a correlation between environmental degradation and war; environmental crises can cause local skirmishes, but a major war requires a political decision that a war would be advantageous. The 1930s Dust Bowl did not cause an American Civil war; when we did have a Civil War, its causes were very different.
Drones. The whole point of drones is to minimize loss of life compared to indiscriminate forms of destruction such as artillery, aerial bombardment, tank battles, and search-and-destroy missions, which killed orders of magnitude more people than drone attacks in Afghanistan and Pakistan.
Cyberwarfare. No doubt cyberattacks will continue to be a nuisance, and I'm glad that experts are worrying about them. But the cyber-Pearl-Harbor that brings civilization to its knees may be as illusory as the Y2K bug apocalypse. Should we really expect that the combined efforts of governments, universities, corporations, and programmer networks will be outsmarted for extended periods by some teenagers in Bulgaria? Or by government-sponsored hackers in technologically backwards countries? Could they escape detection indefinitely, and would they provoke retaliation for no strategic purpose? And even if they did muck up the internet for a while, could the damage really compare to being blitzed, firebombed, or nuked?
Nuclear inevitability. It's obviously important to worry about nuclear accidents, terrorism, and proliferation because of the magnitude of the devastation they could wreak, regardless of the probabilities. But how high are the probabilities? The 67-year history of nonuse of nuclear weapons casts doubt on the common narrative that we are still on the brink of nuclear Armageddon. That narrative requires two extraordinary propositions: (1) That leaders are so spectacularly irrational, reckless, and suicidal that they have kept the world in jeopardy of mass annihilation, and (2) we have enjoyed a spectacularly improbable run of good luck. Perhaps. But instead of believing in two riveting and unlikely propositions, perhaps we should believe in one boring and likely one: that world leaders, though stupid and short-sighted, are not that stupid and short-sighted, and have taken steps to minimize the chance of nuclear war, which is why nuclear war has not taken place. As for nuclear terrorism, though there was a window of vulnerability for theft of weapons and fissile material after the fall of the Soviet Union, most nuclear security experts believe it has shrunk and will soon be closed (see John Mueller's Atomic Obsession).
What the misleading risk factors have in common is that they contain the cognitive triggers of fear documented by Slovic, Kahneman, and Tversky: they are vivid, novel, undetectable, uncontrollable, catastrophic, and involuntarily imposed on their victims.
In my view there are threats to peace we should worry about, but the real risk factors—the ones that actually caused catastrophic wars such as the World Wars, wars of religion, and the major civil wars—don't press the buttons of our lurid imaginations.
Narcissistic leaders. The ultimate weapon of mass destruction is a state. When a state is taken over by a leader with the classic triad of narcissistic symptoms—grandiosity, need for admiration, and lack of empathy—the result can be imperial adventures with enormous human costs.
Groupism. The ideal of human rights—that the ultimate moral good is the flourishing of individual people, while groups are social constructions designed to further that good—is surprisingly recent and unnatural. People, at least in public, are apt to argue that the ultimate moral good is the glory of the group—the tribe, religion, nation, class, or race—and that individuals are expendable, like the cells of a body.
Perfect justice. Every group has suffered depredations and humiliations in its past. When groupism combines with the thirst for revenge, a group may feel justified in exacting damage on some other group, inflamed by a moralistic certitude which makes compromise tantamount to treason.
Utopian ideologies. If you have a religious or political vision of a world that will be infinitely good forever, any amount of violence is justified to bring about that world, and anyone standing in its way is infinitely evil and deserving of unlimited punishment.
Warfare as a normal or necessary tactic. Clausewitz characterized war as "the continuation of policy by other means." Many political and religious ideologies go a step further and consider violent struggle to be the driver of dialectical progress, revolutionary liberation, or the realization of a messianic age.
The relative peace we have enjoyed since 1945 is a gift of values and institutions which militate against these risks. Democracy selects for responsible stewards rather than charismatic despots. The ideal of human rights protects people from being treated as cannon fodder, collateral damage, or eggs to be broken for a revolutionary omelet. The maximization of peace and prosperity has been elevated over the rectification of historic injustices or the implementation of utopian fantasies. Conquest is stigmatized as "aggression" and becomes a taboo rather than a natural aspiration of nations or an everyday instrument of policy.
None of these protections is natural or permanent, and the possibility of their collapsing is what makes me worry. Perhaps some charismatic politician is working his way up the Chinese nomenklatura and dreams of overturning the intolerable insult of Taiwan once and for all. Perhaps an aging Putin will seek historical immortality and restore Russian greatness by swallowing a former Soviet republic or two. Perhaps a utopian ideology is fermenting in the mind of a cunning fanatic somewhere who will take over a major country and try to impose it elsewhere.
It's natural to worry about physical stuff like weaponry and resources. What we should really worry about is psychological stuff like ideologies and norms. As the UNESCO slogan puts it, "Since wars begin in the minds of men, it is in the minds of men that the defenses of peace must be constructed."