Ed Brayton has somewhat of a meta post about rationality and how you could compare it to the study that was done that shows that people who think they’re drinking more expensive wine tend to enjoy it more. The idea is that confirmation bias is something we all need to be careful of if we want to approach the world on its merits rather than how we would like it to be.
I freely admit to being susceptible to this sort of problem. I try not to, I make a lot of effort to approach everything skeptically, but it’s not easy to do and the same tool, my brain, that I use to keep myself from forming the wrong conclusions is the one that’s forming the wrong conclusions.
Here’s a taste of what Brayton had to say on the subject. Read this, then read the whole thing.
I would submit that we do much the same thing when evaluating ideas, claims and arguments. If we hear those ideas expressed by someone we have already determined that we agree with, we are much more likely to agree with them without actually thinking about it. Conversely, if we hear those ideas expressed by someone we disagree with, we are much more likely to reject them out of hand, without giving them any due consideration. This is why what I often call the argumentum ad labelum is so common — it’s a means of dismissing a claim or argument rather than engaging it.