The purpose(s) of living together

In other words, we could ask the question this way: can we find rules favoring the enlargement of the circle of people choosing themselves (coalitions are often the base of our ability to survive) to expand them to the rest of human kind and beyond the kingdom of life.
But like every question, this question must be completed by its counterpart to enable to go further (in a dialectic approach), and we could also add: how can we prevent the assumption of altruism, that enabled us to enter a coalition, from blinding us collectively to assume the defense of our own interests.