Claims like 'Slavery is wrong' are not fully common-sensical, so they must be at least partly theoretical.

Epicurus thought that friendship and conviviality, which require present attention rather than being in an alcoholic stupor, as well as trying to understand and explain things, were the greatest sources of satisfaction in life, so there go most drugs.

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.

If you live in an acquisitive society you are likely to be acquisitive, but it isn't deeply rooted in human nature, except in the sense that it's deeply rooted to be psychologically receptive to your peers and to advertising.

Moral theory develops from the divine command theory of medieval Christian philosophy, mixed up with a bit of ancient pagan virtue theory, to the purely secular moral sentiment and interpersonal reaction theories of Smith and Hume, to Kant's attempt to restore command theory but with something supersensible in the individual rather than God as the source of authority.

There is no single test or formula for producing moral progress anymore than there is for generating scientific truths. It is a process involving theoreticians, fact-gatherers, protestors, martyrs for the cause, authors of first- person narratives who change the way we see and evaluate the distribution of harms and benefits.

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.