Al Franken announced his resignation on the floor of the Senate today, a development that makes abundantly clear that the Democratic and Republican parties have never been more different in modern American history than they are right at this moment. Franken’s speech started off on a surprisingly defiant note, going much farther than he had up until this point in asserting that the charges made against him are not true. But that only reinforces the point I’m making about the two parties, as I’ll explain in a moment: “Over the last few weeks, a number of women have come forward...