This article is excerpted from the new book War No More: The Case for Abolition.

In the late eighteenth century the majority of people alive on earth were held in slavery or serfdom (three-quarters of the earth’s population, in fact, according to the Encyclopedia of Human Rights from Oxford University Press). The idea of abolishing something so pervasive and long-lasting as slavery was widely considered ridiculous. Slavery had always been with us and always would be. One couldn’t wish it away with naive sentiments or ignore the mandates of our human nature, unpleasant though they might be. Religion and science and history and economics all purported to prove slavery’s permanence, acceptability, and even desirability. Slavery’s existence in the Christian Bible justified it in the eyes of many. In Ephesians 6:5 St. Paul instructed slaves to obey their earthly masters as they obeyed Christ.

Slavery’s prevalence also allowed the argument that if one country didn’t do it another country would: “Some gentlemen may, indeed, object to the slave trade as inhuman and evil,” said a member of the British Parliament on May 23, 1777, “but let us consider that, if our colonies are to be cultivated, which can only be done by African negroes, it is surely better to supply ourselves with those labourers in British ships, than buy them from French, Dutch or Danish traders.” On April 18, 1791, Banastre Tarleton declared in Parliament—and, no doubt, some even believed him—that “the Africans themselves have no objection to the trade.”

By the end of the nineteenth century, slavery was outlawed nearly everywhere and rapidly on the decline. In part, this was because a handful of activists in England in the 1780s began a movement advocating for abolition, a story well told in Adam Hochschild’s Bury the Chains. This was a movement that made ending the slave trade and slavery a moral cause, a cause to be sacrificed for on behalf of distant, unknown people very different from oneself. It was a movement of public pressure. It did not use violence and it did not use voting. Most people had no right to vote. Instead it used so-called naive sentiments and the active ignoring of the supposed mandates of our supposed human nature. It changed the culture, which is, of course, what regularly inflates and tries to preserve itself by calling itself “human nature.”

Other factors contributed to the demise of slavery, including the resistance of the people enslaved. But such resistance was not new in the world. Widespread condemnation of slavery—including by former slaves—and a commitment not to allow its return: that was new and decisive.

Those ideas spread by forms of communication we now consider primitive. There is some evidence that in this age of instant global communication we can spread worthy ideas much more quickly.

So, is slavery gone? Yes and no. While owning another human being is banned and in disrepute around the world, forms of bondage still exist in certain places. There is not a hereditary caste of people enslaved for life, transported and bred and whipped openly by their owners, what might be called “traditional slavery.” Sadly, however, debt slavery and sex slavery hide in various countries. There are pockets of slavery of various sorts in the United States. There is prison labor, with the laborers disproportionately being descendants of former slaves. There are more African-Americans behind bars or under supervision by the criminal justice system in the United States today than there were African-Americans enslaved in the United States in 1850.

But these modern evils don’t convince anybody that slavery, in any form, is a permanent fixture in our world, and they shouldn’t. Most African-Americans are not imprisoned. Most workers in the world are not enslaved in any type of slavery. In 1780, if you had proposed making slavery the exception to the rule, a scandal to be carried out in secret, hidden away and disguised where it still existed in any form, you would have been considered as naive and ignorant as someone proposing the complete elimination of slavery. If you were to propose bringing back slavery in a major way today, most people would denounce the idea as backward and barbaric.

All forms of slavery may not have been completely eliminated, and may never be. But they could be. Or, on the other hand, traditional slavery could be returned to popular acceptance and restored to prominence in a generation or two. Look at the rapid revival in acceptance of the use of torture in the early twenty-first century for an example of how a practice that some societies had begun to leave behind has been significantly restored. In this moment, however, it is clear to most people that slavery is a choice and that its abolition is an option—that, in fact, its abolition always was an option, even if a difficult one.

In the United States some may have a tendency to doubt the abolition of slavery as a model for the abolition of war because war was used to end slavery. But did it have to be used? Would it have to be used today? Slavery was ended without war, through compensated emancipation, in the British colonies, Denmark, France, the Netherlands, and most of South America and the Caribbean. That model worked also in Washington, D.C. Slave owning states in the United States rejected it, most of them choosing secession instead. That’s the way history went, and many people would have had to think very differently for it to have gone otherwise. But the cost of freeing the slaves by buying them would have been far less than the North spent on the war, not counting what the South spent, not counting the deaths and injuries, mutilations, trauma, destruction, and decades of bitterness to come, while slavery long remained nearly real in all but name. (See Costs of Major U.S. Wars, by the Congressional Research Service, June 29, 2010.)

On June 20, 2013, the Atlantic published an article called “No, Lincoln Could Not Have ‘Bought the Slaves’.” Why not? Well, the slave owners didn’t want to sell. That’s perfectly true. They didn’t, not at all. But the Atlantic focuses on another argument, namely that it would have just been too expensive, costing as much as $3 billion (in 1860s money). Yet, if you read closely—it’s easy to miss it—the author admits that the war cost over twice that much. The cost of freeing people was simply unaffordable. Yet the cost—over twice as much—of killing people, goes by almost unnoticed. As with well-fed people’s appetites for desserts, there seems to be a completely separate compartment for war spending, a compartment kept far away from criticism or even questioning.

The point is not so much that our ancestors could have made a different choice (they were nowhere near doing so), but that their choice looks foolish from our point of view. If tomorrow we were to wake up and discover everyone appropriately outraged over the horror of mass incarceration, would it help to find some large fields in which to kill each other off in large numbers? What would that have to do with abolishing prisons? And what did the Civil War have to do with abolishing slavery? If—radically contrary to actual history—U.S. slave owners had opted to end slavery without war, it’s hard to imagine that as a bad decision.

Let me try to really, really emphasize this point: what I am describing DID NOT happen and was not about to happen, was nowhere remotely close to happening; but its happening would have been a good thing. Had slave owners and politicians radically altered their thinking and chosen to end slavery without a war, they would have ended it with less suffering, and probably ended it more completely. In any case, to imagine slavery ending without war, we need only look at the actual history of various other countries. And to imagine big changes being made in our society today (whether it’s closing prisons, creating solar arrays, rewriting the Constitution, facilitating sustainable agriculture, publicly financing elections, developing democratic media outlets, or anything else—you may not like any of these ideas, but I’m sure you can think of a major change that you would like) we don’t tend to include as Step 1 “Find large fields in which to make our children kill each other in huge numbers.” Instead, we skip right by that to Step 2 “Do the thing that needs doing.” And so we should.

This article is excerpted from the new book War No More: The Case for Abolition.