I tend to think that a bit more detail might be needed in the contours of the question. I tend to read it as one in which the question is asking if there can be an element of redemption out of the Vietnam War. The positive argument in this might be that America has viewed every conflict since Vietnam in the context of the Vietnam War. Presidents and elected leaders have had to be confronted with the reality that the when wars lose their political legitimacy from the people, bad things cannot be that far behind. At the same time, I felt that a positive argument for the war would have to be that American soldiers became deified and revered in the conflicts that followed. The blaming of the soldiers and the targeting of the veterans as the cause of American angst following the war is something that has not been seen. The Vietnam War taught the lesson that one can "hate the war" and "love the soldiers." From a philosophical point of view, it is a very shaky proposition to hold, but it is something that has become a part of American consciousness. Like so much that seems so very contradictory in American culture, this element has been able to generate support for the men and women of the American armed forces and can be seen as a positive argument in discussing the Vietnam War.