Sci-fi is often a metaphor. I think it's more the themes and questions that science fiction raises rather than the exact predictions that should guide us.

Every profession will have its rogues, of course, no matter what oaths are sworn, but many health care professionals have a real commitment to serving the best interests of their clients.

So why don't we make ourselves the last generation on earth? If we would all agree to have ourselves sterilized then no sacrifices would be required - we could party our way into extinction!

Sometimes we know the best thing to do, but fail to do it. New year's resolutions are often like that. We make resolutions because we know it would be better for us to lose weight, or get fit, or spend more time with our children. The problem is that a resolution is generally easier to break than it is to keep.

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.)

My aim is to advocate that we make this mental switch in respect of our attitudes and practices towards a very large group of beings: members of species other than our own - or, as we popularly though misleadingly call them, animals. In other words, I am urging that we extend to other species the basic principle of equality that most of us recognize should be extended to all members of our own species.

Once we ask why it should be that all human beings - including infants, the intellectually disabled, criminal psychopaths, Hitler, Stalin, and the rest - have some kind of dignity or worth that no elephant, pig, or chimpanzee can ever achieve, we see that this question is as difficult to answer as our original request for some relevant fact that justifies the inequality of humans and other animals.