According to classical utilitarianism, the only intrinsic good is happiness; the only intrinsic bad is pain. That implies no intrinsic value in preserving nature, that preserving an endangered plant is valuable only if it benefits humans or other animals. Intuitively, that seems wrong but perhaps I shouldn't trust my intuition here.

Suppose I grant that pigs and dogs are self-aware to some degree, and do have thoughts about things in the future. That would provide some reason for thinking it intrinsically wrong to kill them - not absolutely wrong, but perhaps quite a serious wrong. Still, there are other animals - chickens maybe, or fish - who can feel pain but don't have any self-awareness or capacity for thinking about the future. For those animals, you haven't given me any reason why painless killing would be wrong, if other animals take their place and lead an equally good life.

Human decision-making is complex. On our own, our tendency to yield to short-term temptations, and even to addictions, may be too strong for our rational, long-term planning.

The belief that the animals exist because God created them - and that he created them so we can better meet our needs - is contrary to our scientific understanding of evolution and, of course, to the fossil record, which shows the existence of non-human primates and other animals millions of years before there were any human beings at all.

What you could say, and what I do argue in the book, is that he doesn't have as much concern for the lives of Iraqis as he does for the lives of Americans, or even frozen American embryos.

After 9/11, the American Red Cross received more than half a billion dollars in donations to help the victims of the terrorist attacks. The families of the victims were already well-provided for by various government funds, so Red Cross simply drew a line across lower Manhattan and offered everyone there financial assistance, whether they needed it or not.

Probability is the guide of life, and of death, too.