William Deresiewicz:

What is it with moral superiority? Why does the need for it consume us? Is it a universal phenomenon, the kind of thing that evolutionary psychologists would concoct an explanation for, or is it specific to a particular time and place—perhaps modernity, the post-Reformation West? Maybe the explanation is as simple as this: it is the only form of superiority that we can all reliably feel, and pretty much whenever we want to. Which begs the question: why must we feel superior at all?