My good friend Craig McNamara, who has done so much great work advancing sustainable agriculture on his Winters-based Sierra Orchards, lost his 93-year-old father earlier this month.

If the surname sounds familiar, it may be because Craig’s father, Robert McNamara, was the former secretary of defense during both the Kennedy and Johnson administrations during the Vietnam War. As defense secretary, McNamara was the public face of America’s war effort. Earlier in my life, when I saw the issue as black-and-white, he was an easy person to hate.

How could such a seemingly smart, rational man justify a war that we had no business fighting and that killed more than 3 million Vietnamese and more than 58,000 Americans? The war dragged on and on, long after it was clear that it was a mistake, in large part because our leaders couldn’t admit they had blundered so badly.

So when McNamara wrote his 1995 memoir, In Retrospect: The Tragedy and Lessons of Vietnam, I was both shocked and relieved.

I was shocked that our leadership could be so screwed up, that it would support its own political positions at the expense of so many lives. For those attending high school in the late ’60s, it was our classmates who never came back from Southeast Asia alive.

But I was also deeply relieved by McNamara’s confession and his willingness to talk about the failure of leadership during that tumultuous time. I believe he should be praised for his honesty. The other players in the Vietnam debacle have not stepped forward, nor do I expect them to. Nor am I holding my breath for former George W. Bush’s Secretary of Defense Donald Rumsfeld’s memoirs.

A few years ago, Craig brought his father to Sacramento for an afternoon discussion at the American Leadership Forum. It was an extraordinary afternoon, to see and hear such a strong mind flesh out the problems of leadership, despite his frail body. My respect for McNamara grew immensely that day.

That day also strengthened my commitment to combat global warming. It helped me realize that it’s impossible to solve a problem until we face the reality that we have one. When our economic and political leaders have their own agendas, their own intractable points of view, admitting there is a problem is the crucial but often omitted first step.

Today, our children are asking us about global warming the same way I asked my parents about Vietnam. Rather than bury their heads in the sands of their own agendas, our leaders should tear a page out of Robert McNamara’s book and candidly assess the issue. A little humility can go a long way.