Jesse Bering, writing in Scientific American, describes some of the research showing that we just can't help thinking teleologically. In other words, we default to believing that things have a purpose for existing, and that the purpose they have is usually to be useful to something (or someone).
Why do we do this? Well because we're driven to it by evolution:
Gopnik argues that human beings have evolved an “innate explanatory drive” that motivates us to seek explanations similar to the way we’re motivated to achieve sexual climax. That is to say, for the sheer thrill and phenomenological bliss of it. Just as those few seconds in bed or on top of the washing machine feel naturally grand and put a smile on your face, so too does lighting upon that fleeting eureka moment in solving a mind-tickling problem leave you glowing. (OK, so maybe doing crosswords or Sudoku isn’t going to have you exactly biting your bottom lip and moaning in ecstasy, but you get the gist of Gopnik’s analogy.)This explains why people just can't help thinking in creationist terms. It also explains why people get so fixated on needing a 'purpose' for the universe's existence. We're just not wired up to accept what appears to be the real answer: it just exists.
In a nice synchronicity, Dan Dennett is talking over at TED on the 'strange inversion of reasoning' demanded by Darwinism. And yes, he manages to get a lot of sex references in too!
Now, I have to say that my gut feeling is that part of the reason we talk teleologically is simply that it's much easier to do. I've noticed this when talking to my kids (6 & 4 years old).
"The sun shines on us to make us warm." Well, no actually the sun shines on us as a result of nuclear reactions, and we exist as a result. The second statement is true, but frankly in ordinary conversation I'm more likely to say the former. So the question is, is this simply an artefact of the way our language is constructed (rather than a psychological predisposition on my part?).