I wasn’t yet following Fred’s blog at slacktivist when he made this original post.  It came out after the Gallup Poll on science attitudes in which only 40% of US respondents said they believed in evolution.  I think Fred sums it up nicely:

It’s hard to know what that means, exactly, to “believe in” or “not believe in” evolution. It’s like not believing in Missouri, or not believing in thermal conduction. Those two examples are a bit different from one another, but they both get at aspects of what this odd sort of disbelief entails.

“Not believing in Missouri” doesn’t affect the Show-Me State one way or another. To say that you don’t “believe in” Missouri is really to say that you deny it exists — that its existence is a fact you refuse to accept. That’s delusion No. 1. Delusion No. 2 is a corollary to that refusal — the idea that your belief or disbelief somehow makes it so. These are delusions because Missouri does, in fact, exist, and because its existence is not conditional upon your “belief” in the reality or unreality of that fact. Both of these deluded notions, I think, are a part of what many of those respondents meant when they told the pollster that they “do not believe” in evolution.

It didn’t help, of course, that Gallup framed the question with leading language about “the theory of Missouri.”

On the other hand, if someone tells you that they “don’t believe in” thermal conduction, it’s likely that they’re not so much saying they deny its existence as that they don’t understand what you mean when you say “thermal conduction.” For all their supposed disbelief, after all, they still avoid sitting on metal park benches in the winter. I suspect that something like that is the case with at least some of that 60 percent — that the more they can be led to understand this thing they don’t believe in, the less they’ll feel the need to disbelieve it.