I am not saying that factory farming is the same as the Holocaust or the slave trade, but it's clear that there is an immense amount of suffering in it, and just as we think that the Nazis were wrong to ignore the suffering of their victims, so we are wrong to ignore the sufferings of our victims.

Pain is pain, and the importance of preventing unnecessary pain and suffering does not diminish because the being that suffers is not a member of our own species.

When you look at food as an ethical issue in the Christian tradition, you don't find very much about it. You don't find, as you do in the Jewish or Islamic or Hindu traditions, a lot of restrictions saying you can eat this but you can't eat that. But what you do find is the idea that gluttony is a sin and that it's something that we ought to be ashamed of.

To be a utilitarian means that you judge actions as right or wrong in accordance with whether they have good consequences. So you try to do what will have the best consequences for all of those affected.

That's a central part of philosophy, of ethics. What do I owe to strangers? What do I owe to my family? What is it to live a good life? Those are questions which we face as individuals.

What is there about the notion of a person, at law, that makes every living member of the species Homo sapiens a person, irrespective of their mental capacities, but excludes every nonhuman animal - again, irrespective of their mental capacities?

In some parts of the world, what you are doing is already apparent.According to the World Health Organization, the warming of the planet caused an additional 140,000 deaths in 2004, as compared with the number of deaths there would have been had average global temperatures remained as they were during the period 1961 to 1990. This means that climate change is already causing, every week, as many deaths as occured in the terrorist attacks on September 11, 2001.