As I continue to watch in amazement otherwise intelligent people say very foolish things on social media, especially Facebook, it occurs to me that now would be a good time for everyone to re-familiarize themselves with a real psychological phenomenon, group polarization, about which Brit Brogaard (Miami) wrote helpfully here.  Remembering this phenomenon is real may help some people think twice before clicking "like" or (worse) weighing in with blather, but it will certainly help the silent observers understand what's going on.