Somebody who eats twice as much factory-farmed products as he or she needs to is clearly doing twice as much damage to the planet. From a utilitarian point of view, that's twice as bad.

No consideration at all is given to the interests of the "pests" - the very word "pest" seems to exclude any concern for the animals themselves. But the classification "pest" is our own, and a rabbit that is a pest is as capable of suffering, and as deserving of consideration, as a white rabbit who is a beloved companion animal.

Well the real concept of basic needs if you cut it right down are simply the physical needs that are unavoidable for all of us. So to have enough calories to keep our bodies going. Have shelter from extreme elements. To have water that is safe to drink, So I think that's the core of it.

We need to recognise that what really matters isn't buying more and more consumer goods, but family, friends, and knowing that we are doing something worthwhile with our lives. Helping to reduce the appalling consequences of world poverty should be part of that reassessment.

If we all think only of our own interests, we are headed for collective disaster - just look at what we are doing to our planet's climate.

If we can put a man on the moon and sequence the human genome, we should be able to devise something close to a universal digital public library.

All the particular moral judgments we intuitively make are likely to derive from discarded religious systems, from warped views of sex and bodily functions, or from customs necessary for the survival of the group in social and economic circumstances that now lie in the distant past.