So if you read the headlines, it kind of seems like the world is a terrible place, full of
violence, despair, and war. But it turns out war is actually declining. We live in the
most peaceful time in human history. There's lots of reasons why, but here are three of
the biggest ones. First, the spread of democracy around the world. International relations
scholars have found consistently that democracies don't fight wars with each other. Now why
is that true? There might be plenty of reasons but one big one is that people who live in
democracies think it's wrong to start wars with other democracies. They're legitimate
governments -- it's wrong to attack them. But there's a flipside to this. Democracies
do often fight wars with autocracies. Luckily, most of the world's countries are democracies now,
so the democratic peace is probably making the world a much more peaceful place. Second
big reason why war is declining is nuclear deterrence. Nuclear weapons, obviously big
and scary. However, nuclear deterrence may have prevented a devastating war between the
United States and the Soviet Union. Everyone recognized that they would lose. Statistical
evidence suggests that that is true -- that most countries are too scared of the consequences
of nuclear war to fight one. There's a dark side, and not just the risk of global annihilation
from an accident. If a country gets nuclear weapons, they feel rather safer in being aggressive
in little ways, you know, small conflicts or bullying around their non-nuclear neighbors.
This weird paradox, that nuclear weapons make the world more violent and more peaceful at
the same time, is called the Stability-Instability Paradox. The third reason that war has declined
has been the spread of the idea of national sovereignty. This idea is hundreds of years
old, the idea that you shouldn't interfere inside the borders of another state. But people
didn't take the idea too seriously, because stealing new land used to be a major cause of
war. Think American European colonialism or World War II. But after World War II, nations
pledged to stop. Since 1976 there hasn't been a single successful war of conquest, except
for maybe Russia in Crimea, really recently. Again though, sovereignty has a flip side.
Sometimes governments go to war against their own people, and poor, weak governments often
collapse into civil war. Sovereignty makes it hard for the international community to
intervene to stop either of those kinds of wars. But on the whole, when you see those
terrible headlines, remember the world's way better off than it ever has been. There's
less war and less violence than almost any other time in human history.
That's something worth celebrating.