Cooperation by Ayn Rand

Cooperation is the free association of people who work together by voluntary agreement, each deriving from it their own personal benefit.

A proper association is united by ideas, not by people, and its members are loyal to the ideas, not to the group. It is eminently reasonable that people should seek to associate with those who share their convictions and values. It is impossible to deal or even to communicate with those whose ideas are fundamentally opposed to one’s own (and one should be free not to deal with them).

All proper associations are formed or joined by individual choice and on conscious, intellectual grounds (philosophical, political, professional, etc.)—not by the physiological or geographical accident of birth, and not on the ground of tradition. When men are united by ideas, i.e., by explicit principles, there is no room for favors, whims, or arbitrary power: the principles serve as an objective criterion for determining actions and for judging  people, whether leaders or members. This requires a high degree of conceptual development and independence.
But this is the only way people can work together justly, benevolently and safely.

The principle of individual rights is the only moral base of all groups or associations. Any group that does not recognize this principle is not an association, but a gang or a mob.