Sometimes it doesn't matter whether one has accurate beliefs about facts as long as one's beliefs have a correct or useful effect in practice. In one STAR TREK novel in which the crew brings aid to a planet suffering from an epidemic, they advise the local healers of the importance of cleanliness. One of them says something like, "Yes, we know dirt attracts disease demons." Later Spock gives her a medication with the statement that disease demons can't abide it. Whether the healers believed in disease demons or germs, what mattered was the treatment being applied. The British Navy realized lime juice prevented scurvy long before vitamins were discovered. Likewise, cooks knew food would spoil if not stored in the proper conditions, even though they knew nothing about bacteria. During medieval epidemics, the spread of disease was controlled by quarantine when doctors still thought illness came from unbalanced humors or malign astrological influences. The heroine of Henry James's short novel DAISY MILLER dies of malaria, which the story attributes to the miasma emanating from the swamps near Rome. Although people then didn't know malaria was spread by mosquitoes, they knew hanging around swamps and other sources of stagnant water often led to catching the disease. Of course, as a literary symbol of ancient, corrupt Europe destroying a young, naive American girl, a swamp works better than a mosquito.
Before astronomers accepted the Copernican model of the planets revolving around the sun, they believed Earth was the center around which the planets (including the sun and moon) and the sphere of the fixed stars revolved. People still managed to navigate by the stars, and astronomers and astrologers could use the incorrect model to predict the movements of heavenly bodies. The triumph of the Copernican model, however, allowed more elegant predictions and opened the way for the revelation that the planets and stars obeyed the same Newtonian gravitational laws as objects on Earth. Contrary to popular belief, by the way, the Earth-centered universe theory didn't mean people thought Earth and the human race were special in a good way. Unlike the heavenly bodies outside the sphere of the moon, Earth was flawed, the lowest point in the cosmos, where the dregs of creation ended up. The moon was imperfect, too; it changed on a monthly schedule, and it displayed visible spots. The planets, sun, and stars were thought to be composed of different, perfect material. The main shock of the Copernican revolution wasn't that we lost our place at the center. It was that the heavens were as changeable as Earth and the objects on it, made of the same kind of matter. Speaking of Newton, the classical laws of physics worked fine in practice for centuries, despite the fact that theories of relativity and quantum mechanics eventually revealed the inadequacies of classical physics on the macro and micro levels.
Often, of course, erroneous beliefs about facts do make a practical difference. Long before Mendel and the later discovery of DNA, farmers knew how to breed animals and plants for desirable traits. However, they also believed in prenatal impressions—that the experiences of pregnant mothers left their marks on the offspring. According to the book of Genesis, Jacob induced his father-in-law's flocks to produce spotted offspring by placing spotted twigs in front of the breeding animals. Columbus was mistaken about the size of the Earth. If he hadn't bumped into a previously unknown land mass by sheer luck, his expedition would probably have been lost long before getting near Asia. When medical science discovered the risks of excessive cholesterol in the bloodstream, authorities assumed dietary cholesterol should be restricted. People unnecessarily reduced their intake of innocent, nutritious eggs, until new studies identified trans fats as the main dietary villain. Pediatricians used to recommend that babies sleep on their stomachs or, later, face up in an inclined rather than flat position, for fear they might spit up and choke. Better understanding of the physiology of sudden infant death has led to a complete reversal, so that babies now sleep on their backs. Ideology drives policy on matters such as punitive incarceration of drug offenders versus treating addiction as a medical problem or what kind of formal sex education (if any) adolescents should be offered in schools—issues in which mistaken beliefs about real-world effects can result in undesired actual outcomes.
What factual beliefs might our present-day culture hold that will be disproved in the future, maybe with real-life consequences? What universally held assumptions of ours might future generations or visiting extraterrestrials consider as absurdly wrongheaded as we consider the heliocentric cosmos or the "humors" theory of disease?
Margaret L. CarterCarter's Crypt