The Madness Of Humanity Part 3: Tribalism

What is the author’s claim about tribalism in paragraph 2? How is this claim developed?

[2]There are gradations4 of tribalism, of course. Only the most extreme would adopt the those-who-don’t belong-are-enemies value system, and only the most aggressive within these will opt to destroy their opponents. Most tribes actually feed on each other’s strength and motivation to pursue a common goal. In his recent book Tribe, Sebastian Junger argues for the importance of such socially-bonding values, citing the detribalization of modern life as a cause for our current social and political misdirection. Tribalism can play a positive role in society and has been key to our survival.