The Difference Between Knowing and Explaining
What drives me nuts about creationists and supporters of Intelligent Design is that they constantly ignore the fact that there is a difference between knowing something happened and explaining how it happened.
We know that evolution happened. The evidence is clear. We just don't know precisely how. But creationists and supporters of Intelligent Design attack our knowledge of how evolution happened as if it somehow proves evolution didn't happen.
An example. You're an arson investigator. You get called to a house that burned down. While you're picking over the ashes trying to determine a cause, a creationist comes up and says to you, "What happened?"
You reply, "A fire. The house burned down."
The creationist says, "How did that happen?"
With a shrug, you reply, "I'm not sure yet. I have some theories."
The creationist says, "So, you make this preposterous claim that the house burned down when you don't even know how it happened? Why don't you just admit that God did it?"
You say, "Because there's tons of evidence here that there was a fire."
The creationist says, "Did you see it happen?"
Creationist: "See? Isn't it obvious that a house can't just 'become' a pile of cinders all by itself? It must have been God."
That's how ridiculous this argument is. You don't have to know how the fire started to know that there was a fire. While we can't fully explain all the mechanisms of evolution yet, a mountain of evidence indicates it did happen.