Why the collusion myth might destroy Democrats in 2020

The end of the Robert Mueller investigation has demolished Democrats' mythology about the 2016 election. That should force them to confront some unpleasant truths about what has happened to their party since President Trump's election -- and, more to the point for 2020, it should force enough introspection to prevent a repeat performance. The idea that Trump colluded with Russia to defeat Hillary Clinton was appealing to many Democrats in the same way any conspiracy theory appeals to the confuse...