CAMBRIDGE, Mass.

HOW should we remember Robert McNamara? As an engaged public servant who participated in some of the most important decisions of the 20th century? A hawk who served as the chief architect of the war in Vietnam? A technocrat who never fully understood the moral implications of his policies? A hero who steadfastly worked to prevent the escalation of conventional war into thermonuclear conflict? All of the above?

It’s impossible to mention his name without starting an argument. Mr. McNamara engendered strong opinions, particularly among those who came of age in the 1960s. People have wanted to know, “Did he ever say he was sorry?” They wanted an apology for his role in Vietnam. The...