We are now returning to the 18th century empirical approach with the new interest in the evolutionary basis of ethics, with 'experimental' moral philosophy and moral psychology. As a result, we understand better why moral formulas are experienced as ineluctable commands, even if there is no commander and even if the notion of an inescapable obligation is just superstition. So moral philosophy has made huge progress.

The (atomic) soul is mortal, and the best life is the one with the least pain and the most pleasure.

In Western Europe and North America some things are better than they were - at least relative to their moral nadirs - such as labour legislation, the opening of the professions to women, intolerance for domestic violence, but so much is still morally unacceptable - the weapons trade, cruel and unusual punishment, economic parasitism.

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.

The moves to contractualism and utilitarianism required some extra ingredients besides mortalism, the denial that God is in charge of the world, and the doctrine that physical and psychological pain are the greatest evils.

Human courtship has some wild extremes. At one end of the spectrum, there is harassment, pestering, blackmail, and an abuse of institutional power, which its targets rightly fear and loathe. At the other end is love, which as Nietzsche said, is beyond good and evil and always deserves our respect and compassion even when it is doomed or destructive. In the wide middle of the spectrum are all the ambiguous and tragi-comic goings-on of our species.

You can reasonably make the intellectual journey from thinking it's permissible to eat shrimp to thinking it's not permissible, or vice versa, whereas our slavery journey was uni-directional. We are as certain we are not going back to that old kind of slavery as we are that we aren't going back to the geocentric universe.