We call 'Slavery is wrong' a moral truth because there is a specific history of theoretical investigation of a particular kind of slavery. We discussed it for centuries in metaphysical, economic, biological, and philosophical terms; we listened to all the arguments pro and con, we read all the testimonies of slaves and witnesses, and we decided. Though this 'we" is not everybody on earth, or even most people, who've never thought about slavery much.

Gentlemanly, principled, helpful behaviour by older men vis-a-vis young women goes unnoticed, but it deserves real moral credit, and we could use more first-person testimony from the beneficiaries and practitioners about that too.

We use and need to use both systems in complex political societies, and we oscillate in our commitments, because both oligarchy and rule by the will of masses have their bad points, as the ancient philosophers all knew.

Moral claims aren't, as a class, truth-value apt or not.

There are people who organise the contest, winners, losers, and people who benefit from the contest taking place.

In the academic setting, you take (typically) lonely, interesting middle-aged men and beautiful, intelligent young women, and everybody's motivations for display and conquest are engaged to the max. Sublimated, this can be a powerful force for the good - Plato had a lot to say about that - but acted upon it can bring evils without end.

Oddly, since by now I've written quite a lot on early modern philosophers, I didn't care for the history of philosophy, which I thought dull and obscure, until I got a minor job writing articles for a children's encyclopedia in the history of science and began to make connections between science and philosophy.