We all entertain some false beliefs about the world and about ourselves. None of us is perfectly rational, after all, and we are all susceptible to misjudgement, bias and self-deception. But suppose we could wave a magic wand and get rid of all our erroneous beliefs. Suppose you could come clean with yourself and have truthful beliefs about everything you care about: the universe, your own self, your loved ones. Is this something we should want? 

Many people seem to think that such a truthful life would be bleak and depressing. In the Book of Ecclesiastes (1:18) we read that too much knowledge can be a heavy burden: ‘For with much wisdom comes much sorrow; the more knowledge, the more grief.’ Similarly, in his famous novel In Search of Lost Time, the French writer Marcel Proust wrote that ‘we are all of us obliged, if we are to make reality endurable, to nurse a few little follies in ourselves.’

Notice the qualifiers in both quotes. Some wisdom may be good for you, but “much wisdom” is a curse. Being totally deluded about reality is probably a bad idea, but who could object against some “little follies”, a few judicious falsehoods to sugar-coat the harshness of reality? In its full weight, Proust and the author of Ecclesiastes concur, the yoke of truth is simply unbearable. 

Other people have expressed a more cheerful view of reality and its woes. In Woody Allen’s Annie Hall, little Alvie is plunged into depression after reading in a magazine that the universe is expanding and all matter will eventually decay. Listless and no longer interested in his school work, he is whisked off to a psychiatrist. But after the shrink is told about Alvie’s condition, his mother remonstrates with him: ‘What has the universe got to do with it? You’re here in Brooklyn! Brooklyn is not expanding!’ With similar down-to-earth insouciance, the Greek philosopher Epicurus shrugged at his own mortality: ‘Death does not concern us, because as long as we exist, death is not here. And when it does come, we no longer exist.’ What’s to worry about? 

You could adopt the same attitude with respect to some inconvenient truths about ourselves. Of course we all have our shortcomings, foibles and personal embarrassments. But are we really such frail creatures that we cannot look at ourselves in the mirror without donning rose-tinted spectacles? Of course, life is quite absurd and death’s the final word, as Eric Idle sang in Life of Brian, but who cares? Why not look on the bright side of life?  

Let’s assume, for the sake of argument, that Marcel Proust was right: we all need some “little follies” to make life bearable. What sort of misbeliefs should we indulge in then? Not just any old falsehoods, you reckon. It goes without saying that we don’t want foolish, crazy or dangerous misbeliefs running amok in our heads. If we are going to stray from the path of truth, we have to tread carefully, or things can get tricky. We must embrace misbeliefs that are both wholesome for body and spirit – or perhaps for society at large – and free of significant drawbacks and side-effects. To phrase the discussion in cognitive immunology terms, we have to look for misbeliefs that are mutualists – a relationship in which the host benefits from the “intruder” – rather than parasites, which only harm their host. 

Some psychologists champion what they call ‘positive illusions’, mild misapprehensions about ourselves that are conducive to health and happiness: the illusion that we are more attractive, talented and intelligent than other people, that we have more control over our lives than is really the case, and that no bad things will happen to us in the future. Some misbeliefs about the universe at large may also yield benefits to individual believers or to society. A prime candidate, of course, is religion. Even some atheists agree with the philosopher Voltaire that, if God did not exist, it would be necessary to invent Him. Scholars of religion have argued that belief in God may be a biological or cultural adaptation, which evolved to solve the problem of large-scale cooperation, or just to soothe our existential anxieties. 

In a similar vein, some philosophers have suggested that metaphysical free will, even though it doesn’t exist, is an indispensable fiction to make our societies liveable. In fact, one can dream up psychological or social benefits for just about every form of superstition, pseudoscience or irrationality. Believers in homeopathy may benefit from the placebo effect, conspiracy theories may satisfy our craving for order in a chaotic world, and the belief that our destiny is guided by the stars may make the universe feel like a cozier place to live in. 

Imagine that, after some diligent searching and considering of different options, we conclude that some of these misbeliefs would indeed be beneficial for us, and do not carry significant risks. Suppose that I conclude that the belief in an afterlife – a pleasant one, that is – would make me a happier person. Or the belief that I will never be afflicted with any life-threatening disease, or the belief that I’m tremendously talented, intelligent, funny—and modest besides. Such delightful notions! Now that I’ve done the hard work and weighed the costs and benefits of different follies, it’s time to embrace the most salubrious ones. I decide, through sheer willpower, to believe!

But of course, it doesn’t work like that. You can’t just flip a switch in your brain and decide to believe that our souls will survive the death of our bodies, or that you are a wonderful violinist. Even if, as a matter of fact, a certain belief would make me perfectly happy, I’d still be incapable of simply making the requisite leap of faith. 

Does that mean that we can’t entertain some pleasant falsehoods? Not quite. It’s just that you can’t choose your own misbeliefs, and you can’t identify them once you have fallen under their spell. It’s easy enough to see through someone else’s self-deception, but it’s a lot trickier to direct your critical gaze inward. In fact, if you could identify your own illusions, you would extinguish them in the process. 

But if you cannot even tell which of your beliefs are false, how can you have any confidence that these beliefs are in fact beneficial mutualists, rather than dangerous parasites? The whole quest for beneficial misbeliefs, it seems, runs into a strange paradox, reminiscent of Joseph Heller’s novel Catch-22. The central paradox of Heller’s absurdist novel about US pilot John Yossarian during the Second World War goes as follows: pilots in the US Air Force were duty bound to fly dangerous missions unless they could prove that they were mentally deranged. If you were of sound mind, of course, you would not want to risk your life in this way; you’d have to be crazy to want any such thing! Consequently, any pilot who freely volunteered to fly must be barking mad and was, for that very reason, exempt from flying missions. Conversely, a pilot who refused to fly was, by this very act, showing evidence of sound mental health and hence was obliged to fly. In Heller’s words: ‘If he flew then he was crazy and didn’t have to; but if he didn’t want to he was sane and had to.’

The idea of voluntarily embracing some beneficial misbelief runs into a similar Catch-22. In order to find out which misbeliefs are beneficial and which are harmful, you have to investigate the attendant benefits and downsides. But once you’ve done that, you are no longer in a position to embrace your favorite misbelief, which means that you’re also unable to reap its advantages. An illusion will only make you happy if you’re fully under its spell, and unaware of it. On the other hand, if you are under the spell of some misbelief, you can no longer identify it and hence you are no longer in a position to tell whether your misbelief is beneficial or harmful. In order to do that, you would need to ‘step out of’ your illusory world, measure it up to reality, and check if you might ever get in trouble. But as soon as you’re even contemplating such a project, the spell will be broken. You have dispelled your own “little folly”. 

Is there any way out of this paradox? Over the years, philosophers and psychologists have tried to identify some. One is known as paternalistic deception or “noble lies”: why not rely on someone else to keep an eye on you? For instance, your wise doctor prescribes a sham pill, persuading you that it will really cure your ailment so that you can benefit from the placebo effect, but all the while making sure that you don’t do anything foolish. But here again, the Catch-22 of beneficial misbelief threatens to rear its head in a different guise: how do you initiate such a paternalistic relation to start with? It won’t do to tell your doctor beforehand: “OK, so from now on you have my permission to deceive me, if you believe it will make me feel better”. Such an agreement would defeat the purpose, undermining your confidence in whatever pill or treatment your doctor goes on to prescribe. And if you can’t know when you’re initiating a relationship of paternalistic deception, how can you be sure that your doctor has your own best interests at heart and will intervene if things get out of hand?

Another way out of the Catch-22 – which appeals to some cognitive immunologists – is to rely on the wisdom of evolution. What if some supernatural misbeliefs have been carefully ‘designed’ by natural selection or, more plausibly, by the swifter process of cultural evolution? Even if God doesn’t exist, it was necessary for evolution to invent him. The problem is that, even if you think such evolutionary accounts are plausible, evolution (whether biological or cultural) does not really care about our happiness. Take the influential theory of scholars like Ara Norenzayan and Joe Henrich, which argues that belief in specific Big Gods has fostered pro-sociality and enabled large-scale human cooperation. This is a plausible story, but as these authors themselves admit, it’s mostly the mean, vengeful, punishing gods that achieve these pro-social benefits. The stick works much better than the carrot. Which raises the question: is belief in a wrathful god who will torture you in hell if you disobey him really good for you, even if we assume that it has helped to scale up human cooperation? Moreover, in evolutionary accounts of religion there’s always a flipside to pro-sociality: being friendly to “us” also means being hostile to “them”. Again, are misbeliefs that lead to intergroup conflict really good for us? As the philosopher Daniel Dennett never tires of pointing out: cui bono? Who or what benefits from the evolved misbeliefs in question? At the very least, cognitive immunologists have found that cultural evolution sometimes creates religious ‘mind parasites’ that subvert and harm the interests of their human hosts, such as the witch hunts in early modern Europe. Such beliefs may be cleverly designed and adapted, but only for their own survival and reproduction. 

Yet another way out of the Catch-22 is to collapse the roles of deceiver and believer into one person – otherwise known as “self-deception”. You may not be able to flip a switch in your brain, but perhaps you can engage in more subtle forms of belief formation, gently nudging yourself in the direction of beneficial illusions. Here’s what the 17th-century philosopher Blaise Pascal, in his famous Pensées, counseled to those who would like to believe in God but can’t bring themselves to do it: just go through the motions. Go to Mass on Sundays, genuflect, utter the prayers, sing along with the hymns. If you keep up with this for a while, Pascal counseled, belief will creep up on you.

But such a project of self-deception cannot tolerate too much in the way of self-reflection. You don’t just have to bring yourself to believe in God; you must also – and simultaneously – forget that this is in fact what you’re doing. As long as you remain aware that you’re engaging in a project of self-deception, I doubt that Pascal’s advice will achieve the desired effect. At the very least, there will always be some nagging doubt at the back of your mind about why you embarked on this whole church-going and hymn-singing project in the first place. And remember that you can only reap the benefits of your beneficial misbelief if you truly and sincerely believe it.

In fact, I can only think of one foolproof way out of the Catch-22 of beneficial misbelief, and it requires a thought experiment. Suppose I offer you a pill that has the following effect. If you swallow it in the evening and go to bed, you will wake up in the morning with a perfect belief in life after death (or whatever other pleasant belief you fancy). Of course the pill would also erase your memory of having swallowed the pill in the first place, or else – again – your belief wouldn’t stick (don’t leave the prescription lying around!). Presumably the pill would also create some internal justifications to shore up your belief: perhaps some bogus ‘evidence’ involving a near-death experience or just the inner sense of certainty that, yes, truly there is a life after this one. Would you swallow such a pill? I’ve asked this question to some colleagues and friends, and to my surprise some immediately said yes: please give us that pill and liberate us from the bleak and unforgiving truth!

For my part, I’m not so sure. Is such a life of voluntary delusion really what you should want? Even if you don’t have any objections against untruthfulness per se, how can you foresee all of the consequences and ramifications of your false belief in an afterlife, or in any other comforting fiction? If you were absolutely convinced that your personal death (or that of other people) doesn’t really matter, because there’s another life after this one, might you risk doing some crazy and reckless things? And if you genuinely believe that you are wonderfully talented, that your health is perfectly fine or that your spouse is not cheating on you (despite extensive evidence to the contrary), is there still not some risk that you will be confronted with the bitter truth later on? Reality, as the writer Philip K. Dick argued, is that which, after you stop believing in it, doesn’t go away. 

At the end of the day, would you not prefer to know the truth, warts and all?