The more ideological and the more emotion-based a belief is, the more likely it is that contrary evidence will be ineffective.
—Robert Todd Carroll
There are times when evidence and logic persuade, and minds are changed. But those instances rarely extend to beliefs that are heavily laden with emotion and meaning. Beliefs that underlie a person's worldview - what I call "weight-bearing" beliefs - are particularly unlikely to be changed by evidence or reason.
In fact, beliefs that bear important weight in a person's identity or meaning structure are likely to be strengthened by contrary evidence, in a cognitive phenomenon known as the backfire effect. Hearing bad things about your political party makes you support it more. Evidence that your cult leader is a fraud (such as a predicted cataclysm failing to arrive) makes you even more loyal to him. This is only surprising to the degree that we conceive of reasoning as a tool for discovering the truth. The backfire effect is entirely predictable from the modern view that reason's function is almost purely social.
Unfortunately, the most interesting, important epistemic problems are precisely those that are wrapped up in emotion, those in which beliefs underlie meaning structures and identity. Suicide, birth, and the meaning of life are such problems. None of us humans (myself of course included) can approach these problems without beliefs we already strongly hold warping our investigation, selecting the facts that must be explained by the theory and those which may be ignored (largely unconsciously), and even determining whether a conclusion feels logical or absurd.
Even when it seems to all of us that a question has a correct answer, we are likely to continue to disagree as to what the correct answer is. As for the important questions, it is not a matter of updating on the right facts. Questions about the meaning and/or desirability of life are, for practical purposes, like theological arguments: solutions carry with them a higher degree of uncertainty than is felt by the holder of the belief.
To the extent that we care about truth, evidence of an epistemic peer who disagrees with us should cause us to have greater uncertainty in our previous belief. Ironically, in reality, disagreement seems to cause us to hold our belief with even more certainty than before. Our natural mental processes seem to be serving purposes other than the pursuit of truth, and often purposes in direct opposition to truth.
Uncertainty is an important part of our picture of the world. It has important consequences: the more uncertain we are in our conclusions, the less drastic action may be justified by them. If we are less than absolutely sure of our conclusions, we should avoid, for instance, excommunicating, exiling, imprisoning, torturing, or killing based on these conclusions. Unfortunately, uncertainty is cognitively difficult to maintain; our minds, it seems, do not have a natural uncertainty function, and tend to reduce complexity to comfortable certainty. Nature has its own reasons why certainty should be comfortable for us, and they are not necessarily our deepest reasons. They are not necessarily based on compassion, charity, and love for the expanding circle; least of all are they based on love of truth. Our squirrel brains treat disagreement as a fight in which we might use all kinds of underhanded tactics in order to win, including molding our actions and policies toward supporting our preferred view of reality.
Since maintaining appropriate uncertainty is not natural to us, if we want to behave charitably and rationally, we must consciously cultivate uncertainty where appropriate. More importantly, we must attend to the real-world consequences of this uncertainty by avoiding the natural tendency to use acts and policies as weapons in support of our beliefs. Given our limited capability for undestanding the world, a just world is one in which no one is forced to suffer for beliefs he doesn't hold. It is fine, I think, to admire the emperor's majestic outfit, but it is a grave mistake to imprison those who claim not to see it.
|Disagreement||→||Uncertainty||→||Charity in acts and policies respecting uncertainty|
|Disagreement||→||Greater certainty||→||Weaponization of acts and policies to promote our side's view|