Earlier quoted context omitted.
> It is precisely when your values are on the "wrong side of History" that you should be defending them the most strongly. Not sure what you mean, people who supported slavery were on the wrong side of history, are you saying they should have defended it strongly because they were "right" according to them?
People who supported slavery were wrong because slavery is wrong. If the South had won the Civil War and conquered the North, they'd still be just as wrong, but opposition to slavery would be more important than ever. History itself justifies precisely nothing.
We're not saying it does. We're saying that when you can tell right from wrong, but you make a selfish / pragmatic choice, that you will be on the wrong side of history. Because we're optimists. We think in the future, people will be better able to tell right from wrong.