On doubt.

I am a scientist. I am unable to separate the doubting part of my scientist training from the rest of my daily life. Take this little anecdote:

When my son was about 9 months old, Mrs. Factician was playing with some little plastic animals on the coffee table with him. When she said, "Where is the giraffe?" he reached for the giraffe. We were astounded (he was 9 months old, mind you, and hadn't shown an indication that he knew which animal was which prior to this point). She put the animal back, and asked him again, "Where is the giraffe?". Again, he picked up the giraffe.

Mrs. Factician and I started to talk about this. She was of the opinion that he had now learned which animal was the giraffe.

I was a bit more skeptical (perhaps not a good thing for a father, to be skeptical of his son, but like I said, I am unable to turn off doubt when I go home from the lab).

So I tested him. I moved the animals around. "Where is the giraffe?". Again, he reached for the giraffe. Wow, 9 months and he's already demonstrated an ability to identify animals. I was absolutely floored. Every test so far had shown that he could identify the giraffe. But still, I had nagging doubt.

I moved the animals around again. "Ok, now where is the monkey?" He reached for the giraffe. He hadn't identified it with the sound "giraffe" at all. A few repeats of the experiment verified it. The giraffe was merely his favourite animal. It would be weeks still until he positively understood the word "giraffe".

A scientist's life is like this. Constant doubt. Constant testing. Constant experimentation with appropriate controls. Re-evaluating old data. Talking about experiments with other scientists.

The new movie "Expelled" will try to make the point that we have stopped testing evolution by natural selection, and have (as scientists) accepted it as some gospel truth. This is total and complete nonsense. We have continued to doubt it, to test it, and to run experiments with controls. But every test, for over 150 years, has come back confirming that evolution by natural selection is true. That's a boatload of data. That's an amazing amount of confirmation.

While it remains possible that there is another, better explanation, but data suggesting that has not been forthcoming. For now, evolution by natural selection is the best description of the data.