One thing, above all, sealed Stevenson's sorry electoral fate. It was the image that he was somehow too smart, too eloquent, out of touch with "ordinary" Americans. In different contests at different times ever since, that same rap has helped defeat a train of other Democratic candidates: Eugene McCarthy's anti-war crusade in 1968, George McGovern in 1972, and most recently John Kerry last time around.Eisenhower was the general responsible for planning the largest and most complex military operation in history was self evidently extremely intelligent. When Stevenson died only a single book was found in his home, he had no record of spectacular academic achievement and he was prone to believing absurd pseudo scientific theories (that nuclear testing might throw the planet off its axis for example). Stevenson was a well connected socialite with a reasonable degree of charm, who happened to believe all the things that liberals believe are signs of being intelligent. Much the same was true of John Kerry in 2004, he had a worse academic record than Bush yet the media were convinced that he was just too smart to connect with the ordinary voter.
Those on the left have a tendency to believe that their political opponents are either stupid or evil and conversely to anoint mediocrities like Kerry or Stevenson as geniuses. Believing that your opponent is evil acts a justification for some of the most appalling personal attacks on their opponents (or their families) as seen with the hysteria about Sarah Palin over the last fortnight. Believing that your opponents are stupid is even more self destructive, as it leads them to consistently be baffled as to how they've been outwitted by the stupid people again. Thankfully in this electoral cycle Democrats are making both these mistakes again.
See also: Clive Crook and Dominic Lawson, via: David Duff and Poor Bastard Marvin