President Trump has decided that it is important that he keep tweeting from his personal Twitter account because it allows him to speak directly to the American people outside of the filter of the mainstream media, by which he means the media’s pesky insistence on fact-checking his comments and including unflattering news in analysis of his presidency. Over the weekend, Trump took this defense of his social-media use to a new place: Not only is his tweeting perfectly fine for a president, but it is defining what it means to be presidential. Donald J. Trump ✔ @realDonaldTrump My use of...