The polarization of the American electorate predated Facebook's arrival on the scene. But a nagging question about the social network has been whether its viral mechanics — and the viral mechanics on YouTube, Twitter, and other platforms — have accelerated the split between the left and the right.

Today we have two stories that examine that phenomenon. The first concerns the fight over the confirmation of Brett Kavanaugh to the Supreme Court. At a time when the sharing of news articles on Facebook is in general decline, the wrenching battle over Kavanaugh has been a top performer on the site. And many of the top performing posts, reports Craig Silverman, are among the most partisan in nature: