Nature's Laws

[SteelCurtain]

I see what you're saying.  Empathy is just one of many factors by which people form a consensus.  But there is still something that is unclear to me in all of this.  If the consensus here in the U.S. never changed, and it was still the consensus that Blacks are only 3/5 human, and that race-based slavery is OK, then what?  Would that mean that Black Americans have no human rights?   

It would mean that society as a meta-entity would not give them the rights that we give them today, and that would be considered moral in that society.

Who knows what the social struggle will be in 100 years? Who knows what practice that we consider completely normal and acceptable today will be the source of a cultural movement to abolish or augment then? For what practice will we be seen as barbaric?

That's the entire point. Cultures and tribes are a constantly shifting mass of mores. I just watched a documentary yesterday where Ugandans (thanks to your wonderful Christian™ brethren) have been whipped up into such a frenzy of hate for homosexuals that they will openly talk about raping women to "give them real sex" to change them, or the accepted practice is to take a gay man to the tallest building in the village and throw him off. If he survives he will be killed by the mob watching hungrily in the street. This is "moral" in that society.

The point is, your "objective morality" would be different had you been born 100 years ago, and would be different if you were born 100 years from now, or if you had been born in the jungle tribes of the Amazon.