Granted, we may try to help our own family members because they share our DNA. Or help someone else in expectation that they will help us later. But when you look at what we admire as the most generous manifestations of altruism, they are not based on kin selection or reciprocity. An extreme example might be Oskar Schindler risking his life to save more than a thousand Jews from the gas chambers. That's the opposite of saving his genes.

Gravity is not a version of the truth. It is the truth. Anyone who doubts it is invited to jump out a tenth-storey window.

The human psyche has two great sicknesses: the urge to carry vendetta across generations, and the tendency to fasten group labels on people rather than see them as individuals. Abrahamic religion gives strong sanction to both-and mixes explosively with both. Only the willfully blind could fail to implicate the divisive force of religion in most, if not all, of the violent enmities in the world today.

Bereavement is terrible, of course. And when somebody you love dies, it's a time for reflection, a time for memory, a time for regret.

Science shares with religion the claim that it answers deep questions about origins, the nature of life, and the cosmos. But there the resemblance ends. Scientific beliefs are supported by evidence, and they get results. Myths and faiths are not and do not.

People sometimes say that you must believe in feelings deep inside, otherwise you'd never be confident of things like 'My wife loves me'. But this is a bad argument. There can be plenty of evidence that somebody loves you. All through the day when you are with somebody who loves you, you see and hear lots of little tidbits of evidence, and they all add up. It isn't purely inside feeling, like the feeling that priests call revelation. There are outside things to back up the inside feeling: looks in the eye, tender notes in the voice, little favors and kindnesses; this is all real evidence.

I do sometimes accuse people of ignorance, but that is not intended to be an insult. I'm ignorant of lots of things. Ignorance is something that can be remedied by education.