Is it Ever Rational to Believe Beyond the Evidence?
by Bill Vallicella
I need to get clearer about the rationality of beliefs versus the rationality of actions. One question is whether it is ever rational to believe something for which one has insufficient evidence. And if it is never rational to believe something for which one has insufficient evidence, then presumably it is also never rational to act upon such a belief. For example, if it irrational to believe in God and post-mortem survival, then presumably it is also irrational to act upon those beliefs, by entering a monastery, say. Or is it?
W. K. Clifford is famous for his evidentialist thesis that “It is wrong always, everywhere, and for anyone, to believe anything on insufficient evidence.” On this way of thinking, someone who fails to apportion belief to evidence violates the ethics of belief, and thereby does something morally wrong. Although Clifford had religious beliefs in his sights, his thesis, by its very wording, applies to every sort of belief, including political beliefs and the belief expressed in the Clifford sentence lately quoted! I take this as a refutation of Clifford’s evidentialist stringency.
If I took Clifford seriously I would have to give up most of my beliefs about politics, health, nutrition, economics, history and a crapload of other things. For example, I believe it is a wise course to restrict my eating of eggs to three per week due to their high cholesterol content. And that’s what I do. Do I have sufficient evidence for this belief? Not at all. I certainly don’t have evidence that entails the belief in question. What evidence I have makes it somewhat probable. But more probable than not? Not clear! But to be on the safe side I restrict my intake of high-cholesterol foods. It’s a bit like Pascal’s Wager. What I give up, namely, the pleasures of bacon and eggs for breakfast every morning, etc. is paltry in comparison to the possible pay-off, namely living and blogging to a ripe old age.
And then there is a problem whether Clifford has sufficient evidence for his evidentialist thesis. It is obvious to me that he doesn’t but I’ll leave that for the reader to work out.
Consider now the case of a man dying of thirst in a desert. He comes upon two water sources. He knows (never mind how) that one is potable while the other is poisonous. But he does not know which is which, and he has no way of finding out. Should the man suspend belief, even unto death, since he has insufficient evidence for deciding between the two water sources?
On one way of looking at the matter, suspension of belief would clearly be the height of irrationality. The desert wanderer must simply drink from one of the sources and hope for the best. Clearly, by drinking from one (but not both) of the sources, his chances of survival are one half, while his chances of survival from drinking from neither are precisely zero. By simply opting for one, he maximizes his chances of reality-contact, and thereby his chances of survival. Surely a man who wants to live is irrational if he fails to perform a simple action that will give him a 50-50 chance of living when the alternative is certain death.
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