Ezra over at Pandagon has an eloquent post about his reasons for supporting John Kerry

...Righteousness, as a habit, rejects certainty; in fact, the angels have a troubling predisposition to wander around issues, which makes sticking in their camp a matter of ideological flexibility as much as judgment. There's no chasm greater than the one Kerry bridged to go from Vietnam war hero to the war's most prominent opponent, but he was right to serve his country and right to fight for an end to the misguided slaughter. It's a lesson he's refused to unlearn, and one he's spent a lifetime applying. And we need it.

There are times when principle matters more than results, when the admirable aspects of certainty outweigh the practical aspects of flexibility. Certainty can inspire, it can direct, it can empower. But it can't always be right. Terrorism isn't an issue on which we can afford to be wrong. Kerry's willingness to adopt new strategies and positions in response to new evidence is his most crucial trait. The terrorists, Cheney says, will not be impressed by our softer side, though, according to the precanned narratives emitted by his voicebox, it seems George Bush's resolve impresses them greatly. But the objective is not to impress those who wish to kill us, it's to destroy them and their networks. Kerry is willing to adapt his approach to that imperative, Bush is unwilling to do anything that may compromise his puffed-out chest and firmly set jaw.

As a practical matter, that is the primary difference between George W. Bush and John Kerry. It's a choice between extreme certainty and an almost excessive flexibility. These are personality traits and I blame neither man for them, I simply judge which I prefer in my president, and that places me in Kerry's camp. But you know what? I forgive Bush his failings, I forgive him his mistakes, I forgive him his transgressions and his lies and his misjudgments and miscalculations and messes. What I don't forgive -- what I will never forgive -- is that he ran for president in the first place. And the reason, dear reader, that I can never forgive him for that, is because he fought to ascend to an office he didn't understand.

I'm not going to pretend to share Ezra's magnamity when it comes to Bush. I will never forgive him for this war. In fact I hope there is still time to bring him and his abetters to justice.

Nor would I call Kerry's flexibility "excessive". A person who changes his/her opinion when confronted with truths that fly in the face of said opinion is smart. More importantly, he is result oriented.

But for the rest, Ezra hits all the right notes. Kerry has emerged as exactly who we need right now.