[Errol Morris, a filmmaker, writes the “Zoom” column at nytimes.com/morris.]

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 publication of his memoir “In Retrospect” (in 1995) only seemed to make people angrier with him.

He said, “We were wrong.” He was reluctant to use the first person. It was always “we,” not “I.” But he did say it. It might not have been enough for many people, but it was an unmistakable admission of error. Still, how do you say you’re sorry for history? It’s impossible to see him as unaware of the role he played in World War II or in Vietnam. What he did give us was his struggle to understand the meaning of what he had done. We got to see him wrestle with history. And thus he serves as an object lesson to many of us.

His refusal to come out against the Vietnam War, particularly as it continued after he left the Defense Department, has angered many. There’s ample evidence that he felt the war was wrong. Why did he remain silent until the 1990s, when “In Retrospect” was published? That is something that people will probably never forgive him for. But he had an implacable sense of rectitude about what was permissible and what was not. In his mind, he probably remained secretary of defense until the day he died....