There could conceivably be circumstances in which an experiment on an animal stands to reduce suffering so much that it would be permissible to carry it out even if it involved harm to the animal... [even if] the animal were a human being.

We should give the same respect to the lives of animals as we do to the lives of humans.

We don't usually think of what we eat as a matter of ethics. Stealing, lying, hurting people - these acts are obviously relevant to our moral character. In ancient Greece and Rome, ethical choices about food were considered at least as significant as ethical choices about sex.

Philosophy ought to question the basic assumptions of the age. Thinking through, critically and carefully, what most of us take for granted is, I believe, the chief task of philosophy, and the task that makes philosophy a worthwhile activity.

But I think the majority of cows, and even more so chickens and pigs, are leading pretty miserable lives.

If animals are no longer quite outside the moral sphere, they are still in a special section near the outer rim. Their interests are allowed to count only when they do not clash with human interests. If there is a clash - even a clash between a lifetime of suffering for a nonhuman animal and the gastronomic preference of a human being - the interests of the nonhuman are disregarded. The moral attitudes of the past are too deeply embedded in our thought and our practices to be upset by a mere change in our knowledge of ourselves and of other animals.

If we compare a severely defective human infant with a nonhuman animal, a dog or a pig, for example, we will often find the nonhuman to have superior capacities, both actual and potential, for rationality, self-consciousness, communication and anything else that can plausibly be considered morally significant.