"Human cooperation is the result of three factors.
First, the fact of differences among men and/or the geographical distribution of nature-given factors of production.
Second, the fact of higher productivity achieved under the division of labor based on the mutual recognition of private property (the exclusive control of every man over his own body and his physical appropriations and possessions) as compared to either self-sufficient isolation or aggression, plunder and domination.
And third, the human ability to recognize this latter fact.
But for the higher productivity of labor performed under divison of labor and the human ability to recognize this fact, explains Ludwig von Mises, "men would have forever remained deadly foes of one another, irreconcilable rivals in their endeavors to secure a portion of the scarce supply of means of sustenance provided by nature. Each man would have been forced to view all other men as his enemies; his craving for the satisfaction of his own appetites would have brought him into an implacable conflict with all his neighbors. No sympathy could possibly develop under such a state of affairs." [Human Action, 144]
The higher productivity achieved under the division of labor and the human ability to recognize this fact explains the origin of the most elementary and fundamental of human institutions:
the family and the family household.
Second, it explains the fact of neighborhood (community) among homogeneous people (families, clans, tribes): of neighborhood in the form of adjacent properties owned by separate and equal owners and neighborhood in the unequal form of the relationship characteristic of a father and his son, a landlord and his tenant, or a community founder and his follower-residents.
Third and most important for our purposes, it explains the possibility of the peaceful coexistence of heterogeneous and alien communities.
Even if the members of different communities find each other physically and/or behaviorally strange, irritating, annoying or worse, and do not want to associate as neighbors, they may still engage in mutually beneficial trade if they are spatially separated from each other. " Secession, the State, and the Immigration Problem by Hans-Hermann Hoppe