Defenders of Confederate monuments and the Confederacy itself regularly say that “we can’t judge people of the past by the standards of today”. They thus take for granted that standards can change over time — that what’s moral at one time might be immoral at another. This view is known as ‘moral relativism’.
You can find many expressions of something called ‘moral relativism’, but most of them are incoherent because they involve a confusion between belief and truth; that is, they involve gibberish like “what’s true for one person isn’t true for another”. Here’s a coherent one: to think and speak in moral terms is only to think and speak of one’s society’s moral customs.
In some senses, of course, it’s true that otherwise similar actions can change their moral status over time. Sending two tons of steel hurtling down a road at 80 mph nowadays is perfectly moral, and 150 years ago, it would have been immoral. But that’s because the roads are different and the cars are different, not because morality is different. The underlying moral issue of safety hasn’t changed; how you implement it has. The same moral ideal will be implemented differently under different circumstances when those circumstances are morally relevant.
But treating human beings as chattel isn’t like that. To treat slavery’s wrongness as if it were a thing of the past, overcome by technological advance, would be to say something like this: Black people were the intellectual and moral inferiors of white people and enjoyed backbreaking manual labor, but then, due to genetic engineering or whatnot, that stopped being true, and so even though it would be immoral for white people to treat Black people as chattel now, it wasn’t back then. Which is absurd.
Treating human beings as chattel did not become evil when it was abolished. If it had been right until abolition — “right by the standards of the time” — then the abolitionists were wrong until their sudden and completely unjustifiable victory.
In general, though: moral relativism is false. If speaking and thinking about morality were just speaking and thinking about one’s society’s customs, then there would be no cross-cultural moral disagreement and there would be neither moral progress nor regress.
Cross-cultural moral disagreement occurs when members of different societies disagree about moral issues. If to think and speak about morality is only to think and speak about one’s own society’s customs, then, if I, as an American, were to say something like, “Women should be able to vote”, all I would be saying is, “In America, women are allowed to vote.” If someone from a benighted regime in which women can’t vote were to try to disagree with me, he might say, “Women should not be able to vote”, but all he would mean would be, “In Saudi Arabia, women cannot vote”. We’re both stating truths about our own societies. According to relativism, the Saudi and I literally cannot disagree about whether women should be able to vote. We each just have customs. As I’m quite sure that Saudis are not just not Americans, but are wrong about whether women should be able to vote, relativism is false.
Moral progress and regress happen when a society has customs but replaces them with better or worse customs. If to think and speak about morality is only to think and speak about one’s society’s customs, then an American two hundred years ago who said, “Women should be able to vote” would have meant, “In America in 1821, women can vote”, so he would have been wrong. The introduction of women’s suffrage was not progress. It was just a change in customs. But customs themselves can’t be evaluated — “we can’t judge the past by our standards”. This would imply that all changes in customs have been irrational. As I’m quite sure that Americans from 1821 were not just not present but wrong about whether women should be able to vote, relativism is false.
Relativism is false, but it’s also starkly inconsistent with the existence of the United States. The Declaration of Independence says, “We hold these truths to be self-evident…” Set aside what the truths are and think about what it is for them to be self-evident. That does not mean that they’re obvious. If they were obvious, then we wouldn’t have to have a revolution about them. Jefferson was asserting that these truths are knowable by human reason; they are not known by a special divine revelation and they are not just expressions of some parochial customs. America is not held together by a common culture; we don’t even quite share a common language. The only thing that can unify our country is a shared moral vision, and the only thing that can convince us to share it is reason to believe that it’s true. If “morality” is only custom, then the United States is incoherent.
The Confederacy tried to destroy the United States because its leaders rejected moral discipline. The heirs of the Confederacy are still destroying the United States because they still reject morality itself. With all of the talk of secession in the air, bear in mind that what Confederate and contemporary seditionists really want to secede from is morality.