engages alternate reality machine
Clearly our Roman traditions must be doing something right. After all, they have allowed us to build a rich and prosperous empire. It is good to follow these traditions of slavery, genocide, and chauvinism when we can, for they contain valuable knowledge.
turns off alternate reality machine
I know my example is contrived and somewhat silly, but somehow we got from ancient Rome to the modern world. This wasn't just due to change in technology or median income, it was from change in traditions and morality. I think it's incredibly egocentric to assume that we, today, have stumbled on the "best" set of traditions.
Which brings me to my real question: Why did you pick those traditions? If you were from a different culture, you would have picked different traditions. If you have some underlying reason for picking those traditions, why not make that the tradition to follow?
I think you've misunderstood a bit because I am not saying our current traditions are the best possible traditions. (That wouldn't even make much sense because they contradict each other frequently.) I am in favor of changing traditions in a gradualist, piecemeal fashion because I think that's the most effective way to make progress.
You might compare it to updating big, messy legacy code systems. You want to do one thing at a time and then run the code or the tests to make sure you didn't break anything and the change works as intended. If you add a bunch of stuff at once, and then there's a problem, it's harder to figure out which change was behind it.
For example, it would probably be helpful to study how cultures and traditions changed in the past. At some point, some guy changed his mind from pro-slavery to anti-slavery without initially wanting to become anti-slavery. How did this happen? If we could identify the sort of thought process that leads to these novel conclusions, we could apply it to our own traditions and figure out beneficial changes.
For slavery, I think he first noticed some kind of problem. Maybe he was a slave owner and didn't like disobedient, unproductive, or dishonest slaves. He may have at first thought this was just a problem with how he treated his own slaves that his neighbors had already fixed.
So he goes and asks his neighbors about it. He's not trying to rock the boat, just make a bit more money. He finds out his neighbors have the same problem. So that pushes him in the direction of seeing it as a problem with slavery in general. But he still expects there will be a solution that keeps slavery more or less in tact.
So then he looks for a solution. He tries different ways of treating his slaves and tries to figure out which result in more cotton production. As he learns about what works, it gradually leads him away from slavery.
This example shows how someone could end up becoming anti-slavery by accident, just by trying to solve immediate, practical problems.
There were also other ways to become opposed to slavery. For example, one could notice that slavery is an exception to widespread traditions that existed at the time. And one could wonder: what is the reason for making this exception? People did wonder that, and they had answers like that black people are less than human. But one could notice problems with those answers. They aren't very intellectually satisfying arguments and they had logical flaws. Or one might talk to a black man for an hour and notice he seems like a normal human.