If individuals with some inheritable variations happen to leave more surviving offspring than others, then these genetic variations will become more numerous in the population. We are now in a position to return to our original questions. We can further check to see whether traits shared by many individuals are those that usually give high reproductive success. I hope we shall also see, throughout the book, that the hypothesis of organization to maximize individual reproductive success uniquely explains a whole world of facts concerning the way living creatures act. Closing with a summary of my own core view.
Human beings are a special case in at least two ways.
The boundaries of your circle are your choice, but it would be entirely natural to include yourself, your genetic kin and descendants, your cultural kin and descendants. Adopting this as your ultimate goal gives an ethic that is consequentialist, objective, and Aristotelian. There is nothing irrational about such broad concern, though it is rare. We agree to follow the moral rules because it is to our own advantage to live in a society in which the rules are accepted. In other words, if you want to maintain peaceful and cooperative relations with your neighbors, don't kill, steal, lie, or break agreements.