No other feature of religion creates a bigger divide between religious believers and modern secular people, to whom it staggers the imagination that anyone could entertain such beliefs. No other feature creates a bigger divide between believers in two different religions, each of whom firmly believes its own beliefs but considers it absurd that the other religion’s believers believe those other beliefs. Why, nevertheless, are supernatural beliefs such universal features of religions?

One suggested answer is that supernatural religious beliefs are just ignorant superstitions similar to supernatural non-religious beliefs, illustrating only that the human brain is capable of deceiving itself into believing anything. We can all think of supernatural non-religious beliefs whose implausibility should be obvious. Many Europeans believe that the sight of a black cat heralds misfortune, but black cats are actually rather common. By repeatedly tallying whether or not a one-hour period following or not following your observation of a black cat in an area with high cat density did or did not bring you some specified level of misfortune, and by applying the statistician’s chi-square test, you can quickly convince yourself that the black-cat hypothesis has a probability of less than 1 out of 1,000 of being true. Some groups of New Guinea lowlanders believe that hearing the beautiful whistled song of the little bird known as the Lowland Mouse-Babbler warns us that someone has recently died, but this bird is among the most common species and most frequent singers in New Guinea lowland forests. If the belief about it were true, the local human population would be dead within a few days, yet my New Guinea friends are as convinced of the babbler’s ill omens as Europeans are afraid of black cats.

A more striking non-religious superstition, because people today still invest money in their mistaken belief, is water-witching, also variously known as dowsing, divining, or rhabdomancy. Already established in Europe over 400 years ago and possibly also reported before the time of Christ, this belief maintains that rotation of a forked twig carried by a practitioner called a dowser, walking over terrain whose owner wants to know where to dig a well, indicates the location and sometimes the depth of an invisible underground water supply. Control tests show that dowsers’ success at locating underground water is no better than random, but many land-owners in areas where geologists also have difficulty at predicting the location of underground water nevertheless pay dowsers for their search, then spend even more money to dig a well unlikely to yield water. The psychology behind such beliefs is that we remember the hits and forget the misses, so that whatever superstitious beliefs we hold become confirmed by even the flimsiest of evidence through the remembered hits. Such anecdotal thinking comes naturally; controlled experiments and scientific methods to distinguish between random and non-random phenomena are counterintuitive and unnatural, and thus not found in traditional societies.