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

My major concern about leaving enhancement to the marketplace is that then the rich will be able to buy themselves genetically superior children and the poor will not - sharpening the class divisions we have now. That problem could be overcome if, genetic enhancement were available to all, subsidized by the state - and that would, over time, have benefits for society as well.

If possessing a higher degree of intelligence does not entitle one human to use another for his or her own ends, how can it entitle humans to exploit non-humans?

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.

There are a lot of weapons that we've developed which we've pulled back from - biological weapons, chemical weapons, etc. This may be the case with armed autonomous robotics, where we ultimately pull back from them.

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.

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.