Ace points to a brilliant article by Dr. Stephen Rittenberg, M.D. at the American Thinker that gets at something I tried to here. Dr. Rittenberg served as a Navy psychiatrist during the Vietnam War and notes:
...one of my weekly duties was interviewing and assessing potential draftees who were seeking to avoid service by claiming mental illness. Many of these were recent Ivy League graduates, students of the humanities, who were active protesters of what they insisted was an immoral war.