Christmas is a rare occasion when we are reminded that we have obligations to people we did not choose to be related to, and that love is not just a spontaneous feeling but something we sometimes really have to work at, with people we may not even much like.

From time to time, it is worth wandering around the fuzzy border regions of what you do, if only to remind yourself that no human activity is an island.

The optimist underestimates how difficult it is to achieve real change, believing that anything is possible and it's possible now. Only by confronting head-on the reality that all progress is going to be obstructed by vested interests and corrupted by human venality can we create realistic programmes that actually have a chance of success.

Science works because the phenomenon being described can be relied on to remain the same. Even in quantum physics, where phenomena are changed by observation, the way in which observation interferes is regular and falls within a limited range of possibilities. Human culture, however, has the nasty habit of never staying the same for very long.

The greatest moral failing is to condemn something as a moral failing: no vice is worse than being judgmental.

I think that internet technologies are making everything so transparent. The arms race of deception and spin against the public trying to keep up with it - I think the forces of spin have to lose. In the corporate world people are finding this. Corporate social responsibility has been on the agenda for a very long time - and a lot of people say it's a kind of green-wash or white-wash - but because there's nowhere to hide anymore, people are coming around to the realization that the only way to be seen to be good is to be good. You can't fake it.

It may not have the virtuous ring of the golden rule, but the maxim "never say never" is one of the most important in ethics.