As human animals, we find it necessary to participate in a hierarchy. However, when a hierarchy gets to be more than, say, 1000 people, it is no longer psychologically rewarding for the individual.
Therefore postnationalism is referring to the understaning that the idea of a nation is, on an emotional level, only superficially benificial to the individual. In return, the individual owes no more than superficial emotions towards his nation.
Postnational Foundation