Peace on Earth? Why Not?

EVER SINCE I was a little girl, I've wondered what it would take to end war. It's probably why I became a historian: I wanted to understand what drives truly profound social change.

As a child growing up in the shadow of the atomic bomb, I used to pray every night, "Let there be no war," but no one seemed to be listening. No surprise, then, that I spent a decade peacefully protesting the Vietnam War. But I'm not a pacifist; I do believe in (the rare) just war and I support international intervention against genocide.

It's hard to imagine a world without war. But don't forget that slavery -- another barbaric human practice -- existed for thousands of years and is now banned around the globe.

What did it take for our species to decide that owning another human being is unacceptable in a civilized society? Centuries of intellectual and religious opposition, followed by an international movement of abolitionists that never stopped preaching, mostly to an indifferent world, why the slave trade was immoral and had to end.

In the United States, the campaign to end slavery heated up when a movement of deeply religious abolitionists cast slavery as a sin and growing numbers of Americans began to condemn the ownership of others as a hideous violation of our nation's most cherished democratic principles. Nevertheless, it finally took a savage civil war to end the slave system.

Still, humans did eventually abolish slavery, so is it conceivable that we could also end war? And where might we look for glimpses of hope?

Science fiction seems like a good place to start. In much of this genre, we enter a future when the human race has evolved and no longer wages war. In the world of Gene Roddenberry's "Star Trek," for example, the people of the Earth long ago learned to settle their differences through negotiation and diplomacy.

In space, however, they still fight defensive wars against species from less evolved civilizations.

We might also think about the blood-soaked soil of Europe, the result of centuries of catastrophic warfare. Today, half a century after the end of World War II, the nations of western Europe -- yoked together by powerful economic and political ties -- no longer fight each other and have grown increasingly wary of using war as an instrument of foreign policy.

Globalization, paradoxically, may one day help put an end to war. In the short term, of course, the rapid expansion of global trade -- unregulated and ungoverned by international institutions -- has intensified ethnic and religious conflict, widened the gulf between rich and poor, and sparked "resource wars" to control oil and water.

But someday, new political institutions may catch up with this dizzying expansion of trade and global culture and right the wrongs caused by rapid globalization. Newly synthesized sources of energy may even make resource wars a thing of the past.

Meanwhile, we should draw upon our rich tradition of intellectual and religious opposition to war. Some of those courageous voices -- Jeanette Rankin, Jane Addams, Albert Einstein, Mohandas Gandhi, Martin Luther King Jr., -- tried, but failed, to prevent war during the last calamitous century.

I have no idea when -- or if -- humans will ever abolish war. It took centuries of seemingly hopeless effort to end slavery. But this much I do know:

Voices that preach peace must never fall silent. They need to speak so loudly that they drown out those who clamor for war. Even if our species is not yet ready to end war, we must always be prepared to create a climate for peace.