Today we present a special Civil War commemorative edition of “What If,” that occasional feature in which my editor, Tom the Butcher, tries to stump me with supposedly unanswerable hypothetical questions. Because of the dignity of the subject, I urged Tom to stick to serious questions only. What if Lincoln had just stayed home and tweeted the Gettysburg address? We must first ask ourselves if the president would have sent out the entire 272-word text in 11 consecutive, tedious tweets of 140 characters each.