Hillary Clinton's strategists have identified Donald Trump's innumerable lies as a major weakness in his campaign for president. They're smart. Trump does lie a lot. He often gets caught lying. Voters want their next president to be trustworthy.
What the Clintonites and their allies in the media don't seem to understand, however, is that if your attacks on your rival's truthfulness are themselves based on lies, your efforts are doomed to failure.
In a recent op-ed column for the New York Times, Charles M. Blow wrote that Trump "is prone to making up his own set of false facts." (Let's leave aside the fact that, by definition, facts are true.)