In the 1930s, isolationism was respectable across the ideological spectrum. Norman Thomas - the president of the American Socialist Party - was an isolationist. Oswald Garrison Villard (former editor of the Nation), Charles Beard, John Dewey, Bernard Baruch and countless other liberal luminaries were isolationists of varying intensity.
John F. Kennedy sent the isolationist America First Committee $100 while he was at Harvard with the note, "what you are doing is vital." But that was the same JFK who wrote "Why England Slept" - his senior thesis-cum-bestseller on why Britain was unready for war. Kennedy's explanation: The British people were unwilling to face reality. The same was true of the United States in the 1930s. The memory of the horror and stupidity of World War I was fresh enough in Americans' minds - as was the ongoing Depression - that the idea of going to war or even engaging in world affairs just seemed unthinkable. So, we didn't think about it. We used language that made things seem OK.
But the problem, as Kennedy learned, is that evil men and dangerous forces don't take a timeout until we're ready to pay attention. And that's where Iran comes in. Seriously challenging Iran just strikes a lot of people as too much to fit on the American plate right now, so we prefer to call Ahmadinejad an "unlikely firebrand" instead of a murderous fanatic.
But whatever we call him, it won't change the fact that Iran is pursuing nuclear weapons and that Ahmadinejad is a particularly kooky religious fanatic (possibly a member of the Hojjatieh, which seeks to foment global chaos in order to hasten the arrival of the messianic 12th imam).
In response to Ahmadinejad's comments, the world has responded with only slightly more outrage than it would if he'd called for trade barriers on pistachios. It's time to wake up.