There’s a place for opinionated journalism; in fact, it’s vital. But our causal, profession-wide smugness and protestations of superiority are making us unable to do it well. Our theme now should be humility. We must become more impartial, not less so. We have to abandon our easy culture of tantrums and recrimination. We have to stop writing these know-it-all, 140-character sermons on social media and admit that, as a class, journalists have a shamefully limited understanding of the country we cover. What’s worse, we don’t make much of an effort to really understand, and with too few exceptions, treat the...