(Commentary by Russell L. Riley, White Burkett Miller Center Professor of Ethics and Institutions and co-chair of the Miller Center’s Presidential Oral History Program) Donald Trump plays only a bit part in Jonathan Alter’s splendid new biography of Jimmy Carter. His name is mentioned on just 17 of the book’s nearly 800 pages, slightly more exposure than Trump got in “Home Alone 2.” But it is hard to read this volume without the mind’s eye turning constantly to the president who was in office as Alter was writing. Why? Because no two presidents in the history of the republic are more unalike i...