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 life-world of human and animal experience, with colours, tastes, solid objects, is a perceptual effect of massed atoms.

Aristotle saw nature as intelligent and purposive, whereas for the Epicureans, and the 17th century 'mechanical' philosophers, there is no intentionality in nature except where there are animal minds and bodies.

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.

People formerly seemed unable to evaluate a woman's c.v. or to accept a range of personal and communicative styles from the exuberant and confident to the sober and pedantic. It's much better than it was, and a number of male philosophers have been extraordinarily helpful in detecting and criticising everyday sexism in the profession.

Epicurus recommends bread and cheese as the staple, and his emphasis is more on avoiding pain than on seeking pleasure, insofar as pleasure-seeking tends to be followed by painful after-effects.

Outside of mathematics and logic, there are common sense truths, such as that it is snowing that normal observers, in a specified context can agree on, subject to vagueness considerations, and theoretical truths, such as that snow is crystallised water vapour, and maybe in-between truths.