Mossberg: Facebook can and should wipe out fake news

Totally false news isn’t a new thing in the United States. In our fourth presidential election, in 1800, two of our most brilliant founders — John Adams and Thomas Jefferson — faced off in a vicious campaign that involved newspaper editors on the take, and numerous false, often personal attacks. Some historians even claim that partisans for Adams spread the rumor that Jefferson was dead. (He won anyway.)
But they didn’t have Facebook to present, amplify, and repeat those