"If you have a prior assumption
that modern life is rubbish and technology is intrinsically evil, then you will place a high prior probability on carbon dioxide emissions dooming us all. On the other hand, if your prior bias is toward the idea that there is a massive plot by huge multinational environmental corporations, academics and hippies to deprive you of the right to drive the kids to school in a humvee, you will place a much lower weight on mounting evidence of anthropogenic climate change. If your prior was roughly neutral, you will by now be pretty convinced that we have a problem with global warming. In any case, anyone paying attention as evidence mounts would eventually converge on the right answer, whatever their prior – though it may come too late to affect the outcome, of course.
There is an exception to this, worth noting.
A prior assumption of zero probability can never be changed. Thus, for example, if you absolutely believe that the Earth is 5,000 years old or so, no amount of evidence can change your mind. If your unshakeable faith tells you there are only red stones, then the fact that I appear to have a blue one is simply god, or possibly satan, making a red stone look blue to test your faith. Just like he did with the fake fossils and the cosmic microwave background. No evidence will modify your prior belief. Your faith makes you impervious.
I guess Bayesian statistics provides a mathematical definition of a closed mind. Anyone with a prior of zero about something can never learn from any amount of evidence, because anything multiplied by zero is still zero. "
This entry was originally posted at http://profpr.dreamwidth.org/479547.html. Please comment there using OpenID.