Researcher Clark McCauley of the University of Pennsylvania writes that “arbitrary division of individuals into two groups, even by flipping a coin, is enough to generate ingroup preference. ”
२० व्या शतकादरम्यान, अशाप्रकारचा फाजील अभिमान बहुतेककरून हिंसक मार्गांनी व्यक्‍त करण्यात आला.