With the Republican National Convention recently concluded in Cleveland, and the Democratic National Convention still under way in Philadelphia, the Gazette invited two presidential historians with long Martha’s Vineyard ties, David McCullough and Evan Thomas, to air their perspectives on the current race.

What follows is an edited transcript of their conversation, which took place at the newspaper office in Edgartown with publisher Jane Seagrave.

Mr. Thomas: I was reminded of a book that I read by an old colleague named Dan Klaidman about the secret war, the drone war. I hadn’t realized the degree to which the president sits there in secret, with his national security advisors, choosing targets, deciding who’s going to live and who’s going to die. These are unbelievably difficult decisions, made in secret. The president is well advised, but at the end of the day, it’s his call.

The president of the United States, any president, every day, is confronted with things that we don’t know about, things that make his hair turn gray, keep him awake, affect his family life. It’s just an unbelievable cauldron that we throw these men — and possibly woman — into. And we’ve got to remember that.

Mr. McCullough: Harry Truman said you have to let the dust settle, and I think it takes about 50 years, before we can really judge a president. Many of these men who have been ridiculed or looked upon askance, in retrospect are looking better and better. Eisenhower, for example. Eisenhower was a superb president. He served his country virtually his whole life. He was highly intelligent. He had a strong sense of history and a strong sense of duty.

He said some things about leadership that I wish were better known. What’s called for in a leader. Number one is character. Experience. Ability. And responsibility. The fact that he did not go to war in Viet Nam. You have to look at what the presidents didn’t do as well as what they did do. The fact that John Adams did not go to war with France was one of the best decisions that any president ever made.

Mr. Thomas: Ike had one great quality — just to follow up on what David is saying — that really struck me. And it’s what I call a confidence to be humble. Eisenhower had an enormous ego, but he knew how to control it, to hide his ego. He’d like to say that he got ahead by being underestimated. He consciously used this as a tactic, but it was intrinsic to who he was. This innate modesty that came from his Kansas roots, and his upbringing, real strict religious upbringing, and his training at West Point, forged the kind of character that allowed him to be confident and humble.

Mr. McCullough: And we are talking about a Republican. The idea that the party of Abraham Lincoln has nominated this totally unhinged man, Donald Trump: Unacceptable, unqualified and uninterested in knowing more than he already knows, which is virtually nothing. I find that one of the most maddening qualities about the man....