'I don't know' -- and that's no act

Later, I was asked about a Newsweek blog she wrote. Reading it bugged me more than hearing about it. She ends with: "But here was Penn, a great friend to the skeptic community, basically saying, 'Don't bother me with scientific evidence, I'm going to make up my mind about global warming based on my disdain for Al Gore.' ... Which just goes to show, not even the most hard-nosed empiricists and skeptics are immune from the power of emotion to make us believe stupid things."

Is there no ignorance allowed on this one subject? I took my children to see the film "Wall-E." This wonderful family entertainment opens with the given that mankind destroyed Earth. You can't turn on the TV without seeing someone hating ourselves for what we've done to the planet and preaching the end of the world. Maybe they're right, but is there no room for "maybe"? There's a lot of evidence, but global warming encompasses a lot of complicated points: Is it happening? Did we cause it? Is it bad? Can we fix it? Is government-forced conservation the only way to fix it?

To be fair (and it's always important to be fair when one is being mean-spirited, sanctimonious and self-righteous), "I don't know" can be a very bad answer when it is disingenuous. You can't answer "I don't know if that happened" about the Holocaust.

But the climate of the whole world is more complicated. I'm not a scientist, and I haven't spent my life studying weather. I'm trying to learn what I can, and while I'm working on it, isn't it OK to say "I don't know"?

I mean, at least in front of a bunch of friendly skeptics?