Many things are naturally repulsive, but are indulged out of necessity or gain. For instance Aristotle wasn't opposed to slavery, yet nonetheless in his writings, now some 2400+ years ago, he found himself obligated to lay out an extensive and lengthy defense and rationalization of such, and he even predicted what would eventually end it:
"For if every instrument could accomplish its own work, obeying or anticipating the will of others, like the statues of Daedalus, or the tripods of Hephaestus, which, says the poet, 'Of their own accord entered the assembly of the Gods.' If, in like manner, the shuttle would weave and the plectrum touch the lyre without a hand to guide them, chief workmen would not want servants, nor masters slaves." [1]
There were millennia of efforts to end slavery, but it's only the technological and industrial revolution that finally succeeded in doing so. But the point is that even though Aristotle was ostensibly not opposed to slavery, he nonetheless knew it was a decision that needed justification because it was fundamentally repulsive, even in a society where it was ubiquitous and relatively non-controversial, thousands of years ago.
This 'natural repulsion' is, I think, some degree of evidence for persistent, if not absolute, morality throughout at least thousands of years of humanity's existence, and I see no reason to assume it would not trend back long further than that.
>Many things are naturally repulsive, but are indulged out of necessity or gain
Most "naturally repulsive" things were accepted just fine in one society or another.
Aristole spent time to defend and rationalize slavery because that was just job, to spend time rationalizing things. Other societies practiced it with no such worries, and found it perfectly natural.
But even if we grant you your "naturally repulsive" actions existing, it doesn't mean they are objectively morally wrong. Just that their moral judgement is not just based on culture and historical period, but also on evolutionary adaptations. These could very well be considered fine in an earlier/later evolutionary stage (in an earlier one, for sure: animals don't have such qualms).
His arguments were generally driven by logic and reason, not rationalization. Rationalization is generally only necessary for adopting views that seem ostensibly inappropriate, which would certainly include these sort of 'naturally repulsive' acts. And indeed his arguments for slavery were some of his weakest precisely because they were uncharacteristic rationalizations.
I completely agree that if you go back far enough in the evolutionary pipeline then my claim becomes invalid. I also think it would not apply to people of a sufficiently reduced IQ. You need to have a minimum of intelligence to understand what you're doing, alternatives, and its consequences on others. But once you have that baseline of IQ then I think morality, and a natural repulsion to certain behaviors, comes as naturally as communication.
>His arguments were generally driven by logic and reason, not rationalization. Rationalization is generally only necessary for adopting views that seem ostensibly inappropriate, which would certainly include these sort of 'naturally repulsive' acts.
I think that's an after-the-fact assessment of what his treatment of the subject was, which we arrive at because of our modern morals.
In his time he, and his audience, didn't think of it as rationalization, but as legitimate use of logic and reason, just like his treatment of other topics.
>But once you have that baseline of IQ then I think morality, and a natural repulsion to certain behaviors, comes as naturally as communication.
Might go the over way around too though: once you go above a certain IQ, it might be easier to treat morality as a fiction naked apes developed, as opposed to something objective, and even discard it entirely.
No, his arguments were materially different in this case. Most of his arguments came from first principles and worked outwards from some baseline; in particular - what is virtue and how virtue, itself, leads to satisfaction in life, and onward to how this can apply to systems and politics in general. But slavery he treated in an entirely different, practically ad hoc, fashion starting from slavery and then trying to shoe-horn in a justification along the lines of what you alluded to already with e.g. natural order and it being an inescapable inevitability.
It was a complete, and poor, rationalization. He even added, almost as a disclaimer, that there was not a complete overlap between 'natural' slaves and legal slaves, giving himself a plausible out to explain the endless examples of the repulsiveness of the institution by applying a no true scotmans fallacy, 'Ahh yes, I would agree with you there. But that is because that is not a natural slave, but merely a legal one.' And this is not my opinion alone. It has long been considered notably weak, especially from an otherwise brilliant man.
And I think that leads into your next issue. I don't think higher intelligence makes it easier to treat morality as a fiction, but rather even average intelligence, without discipline and virtue, makes it very easy to engage in self delusion and cognitive dissonance. Even those conditions are hardly a guarantee - Aristotle certainly had and strived for both discipline and virtue, yet the desire to rationalize what we want to be true, even if we know it is not, is a never-ending struggle that's easy to fail.
"For if every instrument could accomplish its own work, obeying or anticipating the will of others, like the statues of Daedalus, or the tripods of Hephaestus, which, says the poet, 'Of their own accord entered the assembly of the Gods.' If, in like manner, the shuttle would weave and the plectrum touch the lyre without a hand to guide them, chief workmen would not want servants, nor masters slaves." [1]
There were millennia of efforts to end slavery, but it's only the technological and industrial revolution that finally succeeded in doing so. But the point is that even though Aristotle was ostensibly not opposed to slavery, he nonetheless knew it was a decision that needed justification because it was fundamentally repulsive, even in a society where it was ubiquitous and relatively non-controversial, thousands of years ago.
This 'natural repulsion' is, I think, some degree of evidence for persistent, if not absolute, morality throughout at least thousands of years of humanity's existence, and I see no reason to assume it would not trend back long further than that.
[1] - https://classics.mit.edu/Aristotle/politics.mb.txt