Three ways of updating your beliefs, in light of new evidence
People often seem confused that others ignore strong and obvious evidence. How can they not see that so-and-so is a liar, or that such-and-such policy doesn't work? Can't they see that personality flaw? How could they be so in denial?
Often, these epistemic failures are blamed on tribalism (e.g., "beliefs are not about truth, they are just ways we show what side we're on") or on personal failures (e.g., "He is incapable of taking criticism"). But there may well be a more fundamental and more useful explanation than these.
So, why do our human brains so often reject relevant evidence? Wouldn't it be "better" if we just incorporated all evidence rather than rejecting it?
The core of the issue is that seeking truth is just one way of obtaining benefit from our beliefs. Our brains use several different approaches when evaluating evidence. Below, we’ve taken a look at three core things that our brains might seek to maximize – each of which is "better" in a different sense, and each of which dominates some of the time:
It intuitively makes sense that our brains are wired to take into account evidence properly (i.e., in an accuracy-maximizing way) since seeing the world accurately would have helped our ancestors survive. If your ancestors thought there was no tiger by the watering hole when there actually was, they would have been prone to getting attacked by tigers. If your ancestors thought that a berry was safe to eat when it wasn't, they were prone to get poisoned. Accuracy provides a real survival advantage. Some research in cognitive science and philosophy supports the idea that we have “Baysesian brains” theory” – hypothesis-testing mechanisms that update their own internal models of the world using evidence from sensory data, in order to maximize the accuracy of their predictions.
