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.

Of all the arguments against voluntary euthanasia, the most influential is the slippery slope: once we allow doctors to kill patients, we will not be able to limit the killing to those who want to die.

If you're buying animal products and can go to the farm and actually see how the animals are looked after, yes, that's an important point. That's definitely the best way of assuring yourself that the animals are being well treated.

Remember that not everyone is as strong as you are. Be mindful of human weakness, and of the fact that it may be more important, in the long run, to get many people taking steps in the right direction than to have fewer achieving the ideal.

It may be thought justifiable to require tests on animals of potentially life-saving drugs, but the same kinds of tests are used for products like cosmetics, food coloring, and floor polishes. Should thousands of animals suffer so that a new kind of lipstick or floor wax can be put on the market? Don't we already have an excess of most of these products? Who benefits from their introduction, except the companies that hope to profit from them?

I don't understand the notion that modern farming is anything do to with nature. It's a pretty gross interference with nature.

Even in the era of AIDS, sex raises no unique moral issues at all. Decisions about sex may involve considerations about honesty, concern for others, prudence, and so on, but there is nothing special about sex in this respect, for the same could be said of decisions about driving a car. (In fact, the moral issues raised by driving a car, both from an environmental and from a safety point of view, are much more serious than those raised by sex.)