Michael Shermer in the book The Science of Good and Evil develops a theory of provincial morality. The moral theories that have been developed have tended to one of 2 extremes complete absolute morality or completely relativistic morality. Rather then tending to to either of these 2 extremes and rejecting the Aristotelian dichotomy of A or not-A, Shermer attempts to approach the issue from a middle ground.
Humans have moral sentiments, guilt, shame, pride, etc. that encourage us to act in a moral fashion. In order to be viewed as trust worthy, since humans can detect deceit we must not just fake being moral we have to actually be moral. These moral sentiments or emotions come into play even when there is no possibility of reciprocity.
To determine what is moral and what is not, Shermer has a set of principles. Since an action cannot be determined to be immoral in an absolute sense but only determined to be immoral for most people in most places most of the time, the first principle is to ask other parties involved. Is adultery immoral? Ask you spouse how they would feel about it. Some couples have open relationships because both partners have agreed to allow extramarital affairs.
Of course simply asking is not enough without a means to measure the relevancy of the other person's response. The second principle is to not pursue happiness at the expense of someone else's happiness. If an action would reduce other people's happiness, it would not be moral to do it.
The next principle is to not pursue liberty at the expense of another person's liberty. The last principle is to avoid extremism. When innocent people die, extremism in the defense of anything is no virtue and moderation in the defense of anything is no vice.
Since laying out a system of morality is meaningless if there is applicability, Shermer goes on to apply these principles to adultery, pornography, abortion and animal rights. in doing so he attempts to avoid absolutist claims that any of these are always wrong or always right but that there are shades of grey.