When children see animals in a circus, they learn that animals exist for our amusement. Quite apart from the cruelty involved in training and confining these animals, the whole idea that we should enjoy the humiliating spectacle of an elephant or lion made to perform circus tricks shows a lack of respect for the animals as individuals.

Can we really believe that we are living a good life, an ethically decent life if we don't do anything serious to help reduce poverty around the world and help save the lives of children or adults who are likely to die if we don't increase the amount of aid we are giving.

If we're going to live an ethical life, it's not enough just to follow the thou-shalt-nots. … If we have enough, we have to share some of that with people who have so little.

So far as this argument is concerned nonhuman animals and infants and retarded humans are in the same category; and if we use this argument to justify experiments on nonhuman animals we have to ask ourselves whether we are also prepared to allow experiments on human infants and retarded adults; and if we make a distinction between animals and these humans, on what basis can we do it, other than a bare-faced - and morally indefensible - preference for members of our own species?

As for cages themselves, an ordinary citizen who kept dogs in similar conditions for their entire lives would risk prosecution for cruelty. A pig producer who keeps an animal of comparable intelligence in this manner, however, is more likely to be rewarded with a tax concession or, in some countries, a direct government subsidy.

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.

...the proposed air force and army experiments were designed so that many animals would suffer and die without any certainty that this suffering and death would save a single human life or benefit humans in any way at all; but the same can be said of millions of their experiments performed each year in the United States alone.