The co-author of Robert McNamara’s memoirs has himself written a history of Vietnam

What drew you to the idea of applying insights from cognitive science to the Vietnam War?  What made you realize this lens was going to offer something new to a history that's been endlessly analyzed?

Some very talented journalists and historians have tackled the subject.  What could I bring to the table that would further understanding based on my awareness of the principal actors' decency and patriotism (as well as their notorious misjudgments)?  How can one deeply explain serious errors by very intelligent and well-intentioned people? Cognitive science was the only way I could unriddle to myself (and therefore for others) an enormous and deeply disconcerting contradiction: How could such smart people make such stupid errors?  That is the tragic question at the heart of the story. Previous studies of Vietnam by historians and journalists have explored the psychology of decision-making, but usually in terms of particulars (e.g. quirks and shortcomings of individuals, such as LBJ's Texas chauvinism and egotism) ) rather than of universals (e.g. limitations in human perceptions and reasoning). For example, research has shown that no matter how high someone's IQ may be, it has no bearing on how they process (or misprocess) information. This is the first book about Vietnam to offer empirically-based generalizations applicable beyond time and place (Washington and Indochina in the 1960s).

Also, any book about a past war's failure will have present-day applications. Cognitive science shows us that flaws in the perception and processing of information exist in all of us.  They are inherent to human reasoning.  This makes the story of Vietnam half-a-century ago highly relevant to today and the future.

If Kennedy, Johnson, McNamara, Bundy, Clifford, Rusk had a better understanding of cognitive science in 1961 how do you think the course of history would have been changed?

A better understanding of cognitive science in 1961 would have made these men more aware of the potential flaws in their reasoning.  As a result, it would have encouraged them to stop and reflect self-critically--for example, ask themselves "What do we really know, understand, and control regarding Vietnam?"--before making fateful decisions.  It would have made them sensitive to their cognitive vulnerabilities (which are entirely unrelated to good intentions and high intellectual ability).

You were the co-author of McNamara's autobiography IN RETROSPECT.  How much did your work on that book inform this one? Could you have written this one without the extensive first-hand conversations you had with him?

My co-authorship of In Retrospect was crucial.  It helped me understand not just McNamara's grievous errors, but also his humanity and the burdens that go with it.  I pondered what I learned from working closely with him for many years, trying to deeply understand (and therefore explain) the Vietnam tragedy, because I would have one good opportunity to share my unique experience and insights.

At his death, had McNamara, perhaps intuitively, come to an understanding of his, and others failures in Vietnam, that are consistent with the conclusions of this book? 

Yes, I believe he did.  I think that is why he posed the questions I quoted: "How in God's name did it happen? And how can we avoid it in the future?" I believe he came to understand a fundamental truth: the root problem of American decision-making on Vietnam lay not in intentions or abilities, but in mental flaws inherent even in the best of us.  In that respect, the "problem" of Vietnam remains alive and well, and always will.

Despite all the advancements in the understanding of human behavior since the Vietnam War, we are currently entering our 17th year with troops in Afghanistan, we entered Iraq with no plan to win the peace, and we are slowly getting pulled into Syria.  Has America learned from Vietnam? Has the military?

I believe America and its military have remained largely blind to the deeper, more enduring and relevant lessons of Vietnam because we as a people find it hard to confront the truth about the limits of our knowledge, our wisdom, and our massive military power.  Elective leaders "don't like going there" and neither do most Americans. Until and unless we do, we are likely to continue repeating earlier errors. Witness Afghanistan and Iraq.

What group of people would you most like to read this book and what do you want them to learn from it? Is it the politicians who order war, the generals who wage them, your students who will fight them in the future, the public who elects the politicians?  

The politicians who order wars and the public who elects them.  (Generals and soldiers in a democracy do their bidding.) The best way to protect ourselves against our own cognitive limitations and vulnerabilities is--paradoxically--to be aware of them, and internalize the insight that such limitations and vulnerabilities are embedded within each of us--even the most brilliant and well-intentioned.

How do you hope your insights about human behavior in military conflicts will be put to use in the future?

By making leaders more profoundly aware of the limits of military force to solve human problems--and thus to act and decide more wisely.