The spiteful chimps
In the Grauniad, yesterday - how spite is the cornerstone of altruism.
In a nutshell:
One of the most widely used experimental setups to investigate the origins of altruism is the "ultimatum game". Two subjects are asked to share a cash sum of say £100. One of them (the proposer) decides the cut - who gets what. The other (the responder) can either accept the share offered or toss the money back in the proposer's face, in which case, neither of them takes any of it away.So, ethics aren't mathematically logical, they're evolved and rational (cf. Hegel's what is rational is actual and what is actual is rational).
They play the game only once, so there's no opportunity to develop reciprocal altruism. If the responder behaves entirely and rationally selfishly, he or she should accept whatever the proposer is prepared to give. But if the proposer offers less than £25, the other player tends to refuse the share and both leave empty handed. Most people are prepared to forsake personal benefit to punish selfishness. In the language of evolutionary psychologists, we are spiteful.
Note, though - dear reader - that the trigger isn't parity, but taking the piss, so long as the divide isn't excessive people are willing to accept some uneven trade off.
Life is a one shot ultimatum game, and so long as people feel they're getting something out of the social system, they'll put up with inequality - cf. Marx' story about the poverty of living next to a bigger house: it isn't that the next house is bigger, it would seem, but that it isn't too big.
Add on that what will concern folks most is comparison with their peers - the ultra rich are too few and too far (and can be explained as exceptions and we begin to have a model for the psychological acceptance of class society.
Ruddy stupid chimps.