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!

It would be nonsense to say that it was not in the interests of a stone to be kicked along the road...A stone has no interests because it cannot suffer. The capacity for suffering and enjoyment is, however, not only necessary, but also sufficient for us to say that a being has interests - at an absolute minimum, an interest in not suffering. A mouse, for example, does have an interest in not being kicked along the road because it will suffer if it is.

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.

To protest about bullfighting in Spain, the eating of dogs in South Korea, or the slaughter of baby seals in Canada, while continuing to eat eggs from hens who have spent their lives crammed into cages, or veal from calves who have been deprived of their mothers, their proper diet, and the freedom to lie down with their legs extended, is like denouncing apertheid in South Africa while asking your neighbors not to sell their houses to blacks.

Cheats prosper until there are enough who bear grudges against them to make sure they do not prosper.

At the descriptive level, certainly, you would expect different cultures to develop different sorts of ethics and obviously they have; that doesn't mean that you can't think of overarching ethical principles you would want people to follow in all kinds of places.

What is there about the notion of a person, at law, that makes every living member of the species Homo sapiens a person, irrespective of their mental capacities, but excludes every nonhuman animal - again, irrespective of their mental capacities?