There is a certain unusual demand that is placed on ethical theories by modern readers. Not only do they demand that ethics be normative, something we should do, but they demand that the explanation of this normativity be given in terms of how ethics is in the objective best interest of the person acting ethically. This is a demand that most ethical theories meet partially, at best. For example, the ethical theory that I favor says that ethical actions are those that are in the best interests of the group, and thus by being a member of the group acting ethically benefits you somewhat. However normativity springs only partly from this fact; it also arises from the fact that the group will do its best to convince its members that they should act ethically, such that they will feel in some way deficient if they do not (and will punish them if it catches them acting unethically). So here normativity reduces only partially to an explanation in terms of what is good for the individual considering whether to act ethically or not.
My point here is not to investigate the normativity of ethics, but rather to propose a possible explanation for why modern readers of philosophy seem to expect it to be explained in terms of some benefit to the individual. But to do that I must say a few brief words about normativity in general. Really to say that something is normative is somewhat uninformative. It is better to say that something is normative with respect to some desire. For example, opening the door is normative if you desire to leave the house; meaning that opening the door is something you should do, or should want to do, in order to satisfy your desire. So, given this explanation of normativity, my favored ethical theory says that ethics is normative if you desire to be accepted as a member of society. And people seem to want the explanation of normativity in ethics to reduce to: ethics is normative if you desire to be happy / if you desire things to go well for you.
So why do people expect this second explanation of the normativity of ethics? I think some of the blame should rest with the nature of modern morality tales.* For the purpose of our discussion here let us understand a morality tale as entertainment that aims at least partly to encourage the audience to act more ethically. Morality tales are important because many people don’t have the time, desire, or intellectual caliber, to understand a fully rational ethical theory in terms of its most basic foundation, or to apply it to every situation they find themselves in. And more importantly children certainly don’t, and it is in childhood when many of the habits and attitudes that form a basis for behavior are formed. Thus it is important to expose children to morality tales, in order to dispose them to ethical behavior when they are adults.
Modern morality tales are primarily adaptations/modernizations of older fairy tales and Disney movies. Both follow the same pattern: the hero wins in the end because they do the morally good thing. And this teaches the lesson that acting ethically leads to some kind of reward. And this is a bad lesson to teach. Not only does it lead to the attitude that the normative foundations of ethics must be in terms of self-interest, but it puts ethical behavior on a very shaky foundation. It doesn’t take long to realize that acting ethically often has no obvious reward, and sometimes is even detrimental. Such experiences, combined with a Disney-esque attitude towards ethics, is all too likely to lead to a rejection of ethics.
Of course older morality tales were only slightly better. They attempted to instill ethical patterns of behavior by implying that unethical behavior had negative consequences, either in this life or in the next. Although this is still an imperfect foundation for ethics it is a much stronger one. If people have taken these lessons to heart they won’t act unethically, and hence will never realize that unethical behavior isn’t always punished. And if they do act unethically society does do its best to punish such behavior, so it is possible that their unethical actions will cause them trouble (especially as children, who are easily caught), and this will cause the lessons taught by the morality tales to be reinforced.
But even those kinds of morality tales are flawed, because some will realize that in certain situations they will only be punished if they are caught, and that there is no supernatural force watching their every action. Such realizations will weaken their sense of morality, and may even lead to immoral behavior. Thus I think the ideal pattern for a morality tale is to show the moral person as being satisfied with their lives / choices, irregardless of whether things go well or poorly for them. And conversely they should portray unethical people as being forever unsatisfied with their lives, with material rewards never being enough for them. Such a foundation for morality will become a self-fulfilling prophecy; if the lessons have sunk in then they will actually be unhappy when they act unethically, and satisfied when they act ethically, and this will reinforce the idea that lessons taught by the morality tales were good ones.
Disclaimer: Consult with a child psychologist before using these ideas to raise your children. The ideas here are only a hypothesis, and not a theory confirmed by evidence. Although this particular hypothesis can never be confirmed because the government will never approve of a study in which four groups of human children are raised differently simply for the sake of learning how to best instill ethical patterns of behavior.
* Of course by saying that there are to be blamed I am implying that searching for a justification of ethics grounded in self-interest is deficient in some way, but I don’t think that should be a very contentious claim. In some ways to require a self-serving reason to act ethical is to be an unethical person (or, at the very least, a fundamentally selfish person), and thus something that is responsible for this character trait should be blamed.