Yes! And I think the salient point is not only that 18th century Englishmen didn't think slavery was wrong -- again, it's a fact that people disagree radically about morals -- but that the story of the abolition of slavery looks a lot like people learning for the first time that it was wrong. Changing their minds in response to seeing a diagram of a slave ship, for instance. "Oh. Wow. I need to update." (Or, to be more historically accurate, "I once was lost, but now am found; was blind, but now I see.")