For seventeenth-century astronomers, the Epicurean doctrine of multiple worlds separated by void space was seen to fit with the new Copernican system in which every star was a sun, and the universe was a vast place with no centre.

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.

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.

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.

Morality has in the past made progress when we broadened the category of things we weren't permitted to harm (animals, 'infidels'); saw through some delusions and rationalisations about what harms are good for people themselves (prison punishment, hysterectomies for unhappy 1950s wives); and readjusted our for-the-good of others criteria so as to demand only reasonable sacrifices (ceasing to use children as handy chimney sweeps).

About 70% of what I've written about is centered on the clashes and conformities between the emerging life and physical sciences and older metaphysical frameworks in the 17th and 18th centuries. The other 30% consists of one-off essays or researches into other intriguing contemporary topics such as visual experience, aesthetics, social justice issues, and the epistemology of moral knowledge.

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.