The starting point for appreciating that there is a distinctive part of our psychology for morality is seeing how moral judgments differ from other kinds of opinions we have on how people ought to behave. Moralization is a psychological state that can be turned on and off like a switch, and when it is on, a distinctive mind-set commandeers our thinking. This is the mind-set that makes us deem actions immoral (“killing is wrong”), rather than merely disagreeable (“I hate brussels sprouts”), unfashionable (“bell-bottoms are out”) or imprudent (“don’t scratch mosquito bites”).
The first hallmark of moralization is that the rules it invokes are felt to be universal. Prohibitions of rape and murder, for example, are felt not to be matters of local custom but to be universally and objectively warranted. One can easily say, “I don’t like brussels sprouts, but I don’t care if you eat them,” but no one would say, “I don’t like killing, but I don’t care if you murder someone.”
The other hallmark is that people feel that those who commit immoral acts deserve to be punished. Not only is it allowable to inflict pain on a person who has broken a moral rule; it is wrong not to, to “let them get away with it.” People are thus untroubled in inviting divine retribution or the power of the state to harm other people they deem immoral. Bertrand Russell wrote, “The infliction of cruelty with a good conscience is a delight to moralists — that is why they invented hell.”
A previous post on evolutionary origins of morality is here.