If we are concerned about the exploitation of human workers in countries with low standards of worker protection, we should also be concerned about the treatment of even more defenceless non-human animals.

I don't see how anyone could really think that if you have a choice between saving the life of one person and saving the lives of a million people, to say - well, I've saved the one - can you really take that seriously? I can't.

It's also much clearer how much damage the occupation of Iraq is doing to America's reputation and prestige around the world; and that's just starting now to hit home in the United States.

Take for example providing a guide dog for a blind person. That's a good thing to do, right? All right. It is a good thing to do. But you have to think what else you could do with the resources. It costs about $40,000 to train a guide dog and train the recipient so that the guide dog can be an effective help to a blind person. It costs somewhere between 20 and $50 to cure a blind person in a developing country if they have trachoma. So you do the sums, and you could provide one guide dog for one blind American or you could cure between 400 and 2,000 people of blindness.

Without in any way minimising the economic and psychological blow that people experience when they lose their jobs, the unemployed in affluent countries still have a safety net, in the form of social security payments, and usually free healthcare and free education for their children. They also have sanitation and safe drinking water.

Becoming a vegan is a sure way of completely avoiding participation in the abuse of farmed animals. Vegans are a living demonstration of the fact that we do not need to exploit animals for food.

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.