Your next-door neighbor just added a big deck in back, and the guy across the street has a new Tesla in the driveway. They are pulling ahead, and you are falling behind. Nobody likes being outclassed. Meanwhile, there are poor people across town who live on half of what you make, and their kids sometimes go hungry. That, too, bothers you.
Caring about status is innate to human beings – and, most likely, to all sentient life – so we reflexively care about inequality. Likewise, caring about the misfortunes of other people is innate – so we especially loathe inequality when...