The essence of mystical/magical/religious thinking, that which distinguishes it from truly philosophical thinking, may well be something that could be termed “the Mulder Argument” (after fictional FBI agent Fox Mulder on the television show “The X-Files”). This argument is given in four words: “I want to believe.” I’ve run across this argument in many forms. Once, when I had backed a theist who thought she could prove the existence of her God completely into a corner, she escaped by saying, “I just can’t accept a world like that.” Others, asked to provide any sort of justification for their claims fall back on, “I just know.” Philosophical thinking, on the other hand, must be much more ruthless than this. If philosophy is “love of wisdom”, than you must love it wherever it leads you. If you don’t like the direction, learn to live with it. I summed this up to myself, years ago, in a epiphany which I worded as: “My desires are not probative.”
Since it is very central to my view of the world that all important traits of organisms can be explained by evolution by natural selection, I have had some concerns over the question: “How could such a false argument become so ubiquitous in the human species?” Isn’t a trait counter-adaptive if it consistently leads one to believe things that are false? I think I’ve finally come at an answer to these questions, and come at it through another puzzle, specifically, through trying to reconcile my own principle of the non-evidentiary nature of desire with a premise given at various places in Marx and Gramsci, vis. the philosophy of praxis, which states quite the opposite, i.e., that reality is made by humans, especially acting socially, and that in this sense, the desire, or more precisely the will, is in fact probative.
I think it all boils down to taking the correct domain for each argument. Reality is not something that is taken passively by organisms, but is something dynamically modified by them in the course of their existence. This is a very important insight. Organisms alter their “environment” just as much as the environment causes modifications in organisms. In this sense, for a thinking organism like a human, believing in something can often be instrumental to its being so. But there are limitations on this principle. If I believe that I will change the government, then perhaps I can. But if I believe I can literally move mountains with my mind, or with prayer, then that will not happen. I will have to add a liberal quantity of muscle, time and the application of earth-moving equipment to my faith, if I want to bring this result about.
Human minds have evolved to be capable of rational thinking, but it is by no means assured that all thinking that goes on therein will be rational. If I believe that I will change the government, or find food, or win a fight, or find a wife, then perhaps I will. If I believe that I cannot, then certainly I will not. It would be more rational to believe that “maybe I can, if I try hard enough,” rather than simply “I will,” but the more rational belief is more complex, and more susceptible to doubt, and may therefore be inferior to the simple (if less correct) version in many matters of practical success or survival, i.e., matters directly susceptible to natural selection. This would be enough for evolution to select for a tendency to find your desires probative. In order to be equally efficacious, in many practical life matters, as the irrational belief, the rational belief would have to be combined with an iron determination. Iron logic and iron determination may be a more admirable combination than sloppy thinking and blind faith, but it is perhaps a more difficult combination for random mutation to generate. As for the cases in which blind faith leads to an incorrect judgment, well, believing in God or not believing may in general have far less effect on the existence or non-existence of your posterity than whether or not you believe you will successfully woo your wife.
Note that I am not saying that there is a “gene” for the Mulder Argument. I am just saying that a predilection for believing what you want to be true, however complexly coded in genes, memes and individual experience, may in general lead to some differential reproductive success.
But none of this makes blind faith a rational argument for deducing the nature of things as they are, as opposed to (within a limited domain) things as they will be. The will to believe probably yields even more success if it is tempered with a realistic appraisal of when to apply it and when not to (and, just possibly, when it really makes no difference one way or the other). This is essentially what Gramsci was trying to get at with his oft-cited “pessimism of the intellect; optimism of the will.” Despite the theological overtones, this same insight is reflected in a quotation popular within another tradition I’ve had some exposure to: “Oh Lord, give me the serenity to accept the things I cannot change [including the evidence of your own non-existence!], the courage to change the things I can, and the wisdom to know the difference.”