An adequate moral theory would probably be one very close to a combination of Social Contract Theory and Cultural Relativism.

In social contract theory one assumes the following four conditions (put forth by Hobbes) might exist without it:

1. equality of need - Each of us needs the same basic things in life, in order to survive; and that we are all very much alike!
2. scarcity - Each of the basic needs are in short supply. We have to work hard to get them, even if there aren't enough to get around.
3. the essential equality of human power - Since there aren't enough needs to go around, and we want to live as good as possible, then we must decide who gets them! The problem is that we are all too alike in order for anyone of us to be controlling all of the time.
4. limited altruism - Whenever there is a conflict of vital interests, people would surely think of themselves before anyone else.

Because of the previous four reasons we would all be in a state of war. In fact this, indeed, is what happens when a country's government falls, and we are in a state of anarchy. Noting to the points outlined previously, one may surely see that Social Contract Theory works well to keep eachother in check. In this way we may make sure that everyone is doing his ``duty'' for society, and in return others would also do their duty in society.

Now this works very well for essential living conditions (e.g.: murder, assault, &c.) but what of the more fringe conditions. These fringe conditions may be issues like abortion, homosexuality &c. On these issues, one may adopt the Cultural Relativist Light view. By cultural relativist light view, i mean on which takes the essential good point of cultural realtivism but allows for change. For example, if we were to take a strict cultural relativist view on slavery, then we could never progress, and change would never come.

First let me highlight some of the aspects of cultural relativism. With cultural relativism, we have the fact that different societies have different moral codes. As such, there can be no objective standard that can be used to judge one societal code better than another. On the other hand, the moral code of our own society has no special weight (for or against.) Each society determines what is right in their society. In other words, what is, is right. And finally, we cannot be haughty enough to assume that we, as a society, can judge another society's conduct as ``immoral.'' The key in that last statement is tolerance.

Now, it might be apparent what some of the pitfalls of this strict cultural relativism view might be. For one, we could no longer say that certain conduct of other societies are morally inferior to ours, even in the light of overwhelming evidence to the contrary. Consider, for example, the issue of anti-semitism. Suppose a country decided to destroy Jews? Cultural relativism would make it difficult for us to say that the action of anti-semitism and violence toward people of Jewish descent is wrong. Additionally, we could (mistakenly) decide whether or not our actions are wrong based on the current standards of society. For example, if I were a wealthy landowner in the South around early 1800's then i would say that it's right for me to own slaves based on the current standards of society. I am sure that most of us would now-a-days agree that slavery is immoral.

It is in cases as those above where the Social Contract theory would help to fight against the pitfalls of cultural relativism, while still keeping many of the good points of cultural relativism (being open minded, avoidance of the mindset of the existance of completely objective morals.) Social Contract theory would note that these people are keeping their bargain (contributing to society) while receiving none of the benefits! This is one of the basic arguments to the so-called problem of Civil Disobedience.