On Wednesday, the Welcome PAC, a center-left political action committee favored by the proponents of the abundance and popularism movements, held its third annual “WelcomeFest” gathering in Washington, D.C. It was a moderate sort of mess-around, the kind of place where a college student could introduce himself as a former member of the college Republicans, looking for a home in the other party. Based on what I saw, there were across-the-aisle matches to be made. The first panel’s speakers set a