The thing that makes Calhoun importantly different from people like Washington, Jefferson, or Woodrow Wilson, is that Calhoun did nothing positive to make up for all of the terrible things he said and did. We can honor those three for the good things they did, and still make sure we are aware of the bad things they did. With Calhoun, he was originally being honored for the bad things he did, which is why his name must be removed from monuments. (Even though it should still stay in history books.) The same goes for anyone who fought for the Confederacy.