There has to be a certain amount of convergence of attitudes, beliefs, and dreams to act as a cohesive force for a society to work. From el gato malo at boriquagato.com:
the underpinnings of civilization: why melting pots work and salad bowls don’t
the history of civilization is far less top down than what is taught in the tiresome tutelage of kings and conquests. mostly, it’s a bottoms up phenomenon of “trying things, seeing what works, and retaining that knowledge in useful forms.” if one were seeking a definition for “culture” you could certainly do a lot worse than that. the meaningful history of a people emerges from the people. it comes to determine the underlying salients and presumptions by which we may interact with and relate to one another.
if we posit the idea of the social contract not as a literal thing but rather as a metaphor for the evolved and emergent societal systems and mores coalescing out of the sort of positive law substrate that comes to underpin the expected relationships of groups of people through their repeated, successful interaction, then we must rapidly come to some interesting conclusions about the impossibility of such emergence without a certain degree of convergence in attitude and belief.
it is for this reason that i will argue that of the two competing theories of societal structure, melting pot and salad, that only the former is really capable of supporting an actual and functional social contract and that as we have moved from the flourishing former to the “multi-culti melange” of salad speak that we have become rudderless in our lack of shared metaphor and expectation and therefore lose our ability to live with one another in productive fashion or perhaps, increasingly, at all.