There’s a good lesson here. Whatever else we know about 2012, we know we will have many more Stephanopoulos moments ahead. Though it might be more satisfying to thunder against the injustice, there are other, possibly more effective ways to expose the bias.

On the social issues especially, the media narrative is that Republicans are obsessed. The truth is that at a time when millions of Americans can’t find work, when our Middle East policy is in turmoil, when the future of Mr. Obama’s signature legislative achievement—health care—is in question, every Republican in the running is itching for the opportunity to talk about how he would address these things.

In sharp contrast, it was Mr. Stephanopoulos and Ms. Sawyer who showed themselves consumed with nonexistent initiatives on contraception and what you might say to gay friends who are sitting in your living room. Saturday night on ABC, we saw this bias in its full, condescending form.

We also saw something less well appreciated: that a Republican candidate can turn it to his advantage.