We are constituted so that simple acts of kindness, such as giving to charity or expressing gratitude, have a positive effect on our long-term moods. The key to the happy life, it seems, is the good life: a life with sustained relationships, challenging work, and connections to community.

I think there's some evidence that when it comes to being a doctor or nurse, a police officer or therapist, that empathetic engagement leads to burn-out. Imagine if you're dealing with severely ill children, and you felt their pain all the time, and the pain of their parents - you wouldn't be able to do that job for very long. It would kill you.

When you start writing things to try to persuade someone who's not already part of your guild or your profession that something is interesting, it forces you to ask yourself, "Well, why is this interesting?"

I have huge admiration for people who think like the effective altruist, who try to rationally think about how they can change the world for the better, and who try not to be swayed by irrational considerations, such as skin color or whether or not someone lives in the same neighborhood.

And empathy is narrow; it connects us to particular individuals, real or imagined, but is insensitive to numerical differences and statistical data.

What I mean by "empathy" is putting yourself in other people's shoes, feeling what they feel.

Over the last few years, I've been focusing on questions having to do with the self, and questions having to do with morality. I'm very interested in why we do good things, or bad things, and where moral judgments come from.