10 Things We Thought Were True Before the Scientific Method

By: Nicholas Gerbis

Experiments! A critical part of the scientific method. These young women participate in an experiment that's designed to monitor their brainwaves while watching TV commercials.
Experiments! A critical part of the scientific method. These young women participate in an experiment that's designed to monitor their brainwaves while watching TV commercials.
© David Levenson/Corbis

Historically speaking, science has dragged us out of some pretty embarrassing and dangerous parties. Hey, science can identify. It dabbled in some pretty far-out ideas in its youth, too.

Ask science about some of its more embarrassing moments, and it will probably bore you with some lecture about how it used to totally be into logic and deduction (a top-down approach that infers specific cases from general principles), but then matured and got into induction (a bottom-up approach that draws broad conclusions from many observations).


Of course, science will downplay how long and embarrassing that adolescence actually was. Its dalliance with the it's-so-wrong-but-feels-so-right natural philosophy of Aristotle outlasted the Dark Ages by centuries. In fact, science didn't really shake its (literal) demons until a 16th-century intervention by Galileo, who hit it with some shattering observations, and by Francis Bacon, who made it take a hard look at itself. After that, science moved out of its parents' basement, boxed up its astrology posters and got a 9-to-5 job doing evidence-based inquiry via observations, hypotheses, data gathering, experimentation and testing, aka the scientific method.

But it had some great stories to tell.

10: Bodily Humors

The four temperaments (based on the four humors) left to right: phlegmatic, choleric, sanguinic and melancholic. This illustration appeared in Frank McMahon's "Psychology, The Hybrid Science."
The four temperaments (based on the four humors) left to right: phlegmatic, choleric, sanguinic and melancholic. This illustration appeared in Frank McMahon's "Psychology, The Hybrid Science."
© Bettmann/Corbis

Without a proper methodology, reason alone can lead you down a lot of blind alleys, so it comes as little surprise that the father of Western medicine also sired his share of quack ideas.

For example, Hippocrates sought natural causes for supposedly supernatural ailments, including the "sacred disease" of epilepsy -- then viewed as evidence of possession by gods or demons. He also pioneered the wrongheaded notion of bodily fluids, or humors, which he said determined human health, appearance and disposition. Medical practice based on balancing blood, phlegm, bile (also called choler) and black bile (aka melancholy), each purportedly regulated by a different organ, persisted until the mid-17th century. Its legacy lives on in words like sanguine (Latin sanguineus "of blood," meaning optimistic or positive) and melancholy (depressed) [sources: Encyclopaedia Britannica; NLM].


Physicians tried to regulate humors through diet and exercise, and by studying bodily evacuations like urine. So far, so good. The problem was, they reduced every ailment to these causes, mistreating or ignoring the roots of painful and deadly disorders for centuries. Indeed, far from abandoning the flawed fluids, practitioners doubled down on them, gradually tying humors to qualities (wet/dry, hot/cold), elements (earth, air, fire and water), seasons and stages of life. Similar ideas persist today in Indian Ayurveda and traditional Chinese medicine [sources: NLM; Science Museum (UK)].

9: Cosmic Shells Surround Earth

It took us a REALLY long time to arrive at our current model of the solar system.
It took us a REALLY long time to arrive at our current model of the solar system.

Ancient Greek astronomers grappling with the various zigs, zags and tilts of heavenly motions spun off some novel explanations. Some of them even orbited near the truth. Like the Sumerians before him, Anaximenes noted in the sixth century B.C.E. that planets rambled solo across the stellar backdrop. But he also encased the stars in a rigid, eternal sphere that he said rotated around Earth, an idea that would outlast geocentrism and stick around until Edmund Halley observed the sovereign motion of the stars in 1718 [sources: Belen et al.; Brandt; Graham; Kanas].

As further observations strained the model, ancient astronomers kept adding shells. They stuck stars in shells, planets in shells -- they even snatched the sun and moon from their former free-floating home in the air and stuck them in shells. Some said the stars, sun and moon were just holes in some colossal cosmic colander that revealed the holy fire beyond. When blocked, these holes produced moon phases and eclipses [sources: Graham; Allen; Kanas].


This piling-on of spheres culminated in charmingly and ludicrously complex systems invented by Eudoxus in fourth-century B.C.E. , which entailed up to 27 nested and linked spheres, each spinning on its own axis and influencing the others [sources: Allen; Kanas]. Eudoxus would have invented more, but William of Occam traveled back in time and hacked him with a razor.

8: A Central Fire, a Counter-Earth and a Few Epicycles

Many of Claudius Ptolemy's ideas about the cosmos dominated, that is, until Copernicus came along.
Many of Claudius Ptolemy's ideas about the cosmos dominated, that is, until Copernicus came along.
© Leemage/Corbis

Those ancient Greeks also believed the Earth was round two millennia before Columbus or Magellan sailed. Some argued against geocentrism, too -- just not always for the right reasons.

Take the Pythagoreans, the semimystical group founded by famed mathematician Pythagoras in sixth century B.C.E. that removed Earth from the center of the universe for various reasons. To them, Earth circled a Central Fire, as did the sun, moon, planets, stars and a made-up counter-Earth (aka antichthon). At the time, setting the Earth in motion represented a radical shift in thought, but then the Pythagoreans -- who avoided beans, picking up fallen objects or touching white roosters -- waltzed to their own tune: the music of the spheres [sources: Allen; Burnet; Lewis and Chasles; Toulmin and Goodfield].


If anything, attempts to salvage geocentrism in light of contrary observations were just as wacky and far more byzantine. Mercury and Venus, whose travels appeared tangled with the sun's, were moved inward or set in orbits around it, even as it orbited us. In the second century, Claudius Ptolemy explained retrograde motion, the apparent backing and looping of planets caused by differing orbital speeds, by resorting to orbits-within-orbits called epicycles. This Aristotelian-Ptolemaic cosmology dominated until Nicolaus Copernicus put the sun back in the center where it belonged, and Galileo proved him right [sources: Encyclopaedia Britannica; Gagarin and Cohen; Toulmin and Goodfield; Yost and Daunt].

7: All Matter Is Made From Water ... or Is It Air?

The four elements: earth, water, air and fire
The four elements: earth, water, air and fire
Thomas Vogel/E+/Getty Images

To early Greek philosophers, all matter was made of a single substance, even if they couldn't agree what it was. For astronomer and geometrician Thales, it was water; for Anaximenes, it was air (both lived in sixth century B.C.E.). Far from arbitrary, these choices stemmed from observations of changing states of matter. Anaximenes, for example, saw air grow visible and dense as it cooled into mist and then rain, and assumed it would condense further into earth and rock [source: Encyclopaedia Britannica; Encyclopaedia Britannica; Cohen].

Later, Plato, always the overachiever, tapped four elements for his world: earth, air, fire and water. Aristotle added a fifth, ether, to describe heavenly bodies. By mixing and matching these elements, they could explain, for example, why wood was solid (part earth), but also floated (part air) and burned (part fire) [sources: Armstrong; Plato].


The underlying idea -- that, as Democritus said around 440 B.C.E., all matter consists of imperceptibly tiny things -- approached the truth, but useful evidence of real atomic theory lay far in the future, in Robert Boyle's 1662 experiments with air pressure and vacuums. It would take another century-and-a-half before English chemist John Dalton would advance an accepted atomic theory in 1803 [source: Berryman].

6: Spontaneous Generation

Not entirely sure how oysters form? Neither were early natural philosophers who thought, under the guise of spontaneous generation, that the seafloor could just spawn them.
Not entirely sure how oysters form? Neither were early natural philosophers who thought, under the guise of spontaneous generation, that the seafloor could just spawn them.
Spike Mafford/Photodisc/Thinkstock

Whence does life arise? How, asked early sources, can maggots simply appear in a corpse or oysters just show up on the seafloor? Greek natural philosophers, who thought that all matter held inherent qualities, said life could arise from base matter, given the right conditions. Along similar lines, the ancient Chinese thought bamboo spawned aphids [sources: Brack; Simon].

This idea of spontaneous generation would lead to some delightful experiments, absurd findings and voluminous vitriol spilled by the likes of Voltaire and his 18th-century contemporaries. But the laying of scientific eggs really began in the early 17th century, when Flemish physician Jan Baptista van Helmont said mice would spontaneously arise from a soiled shirt placed in a vessel containing wheat grains, and that scorpions could spawn from a basil-lined brick mold [sources: Brack; Simon]. No word yet on whether a live hamster will issue from a Jamba Juice made with chia seeds and whey protein.


En route to the truth, the science world would detour through two hotly competing theories: Preformationists said all embryos existed, fully formed, in eggs or sperm (which some claimed were like infinite matryoshka dolls reaching back to Adam and Eve), while the epigenesists argued that life arose from other matter but couldn't agree on the underlying force [sources: Alioto; Maienschein].

The resulting arguments were vicious and frequently ludicrous, but efforts at disproving spontaneous generation ultimately drove improvements in scientific rigor and experimental design that helped yield the right answers [source: Encyclopaedia Britannica].

5: Miasma Theory

Victorian Londoners thought their crowded city was bursting with various foul miasmas.
Victorian Londoners thought their crowded city was bursting with various foul miasmas.
© The Print Collector/Corbis

As our previous example demonstrates, even after the advent of the scientific method, new theories can require some time to overcome the force of authority and tradition, especially if the old ways appear to work.

Take miasma theory. Dating back at least to Hippocrates, it attributed illnesses to foul airs, which it blamed on harmful plant or animal exhalations or tiny bits of windborne, decaying matter. Because the idea drove healthful reforms in housing and sanitation, it often succeeded in reduced cases of illness, so it's no wonder it became popular in smelly, overcrowded Victorian London. Nevertheless, by masking the true culprit (bacteria), it contributed to many unnecessary deaths [sources: Science Museum UK; Sterner; UCLA].


In a somewhat ironic twist, one of London's leading proponents of miasma theory helped to disprove it, at least where cholera was concerned. William Farr, a pioneer of epidemiology and health statistics, provided vital cluster data during London's 1854 cholera outbreak. John Snow famously used this data to trace the waterborne disease to a Broad Street water pump. His work, and that of pioneers like Ignaz Semmelweis and Joseph Lister, would later help Louis Pasteur and Robert Koch prove germ theory. But, for now, it demonstrated the scientific method's invaluable capacity for self-correction [sources: BBC; Science Museum UK; UCLA].

4: Maternal Impression

The idea of maternal impression certainly made for some interesting stories.
The idea of maternal impression certainly made for some interesting stories.

Clearly, medicine was slow to emerge as a respected and rigorous field of study. Case in point: Mary Toft, the woman who in September 1726 convinced at least a dozen doctors that she could give birth to dead rabbits and rabbit parts. Repeatedly.

Let's pause to let that sink in.


Although the scientific method was well-established in some circles, medicine remained a stew of ideas, peppered heavily with quackery and pet theories. The burgeoning field of heredity still accepted maternal impression, the millennia-old idea that whatever a pregnant woman saw or felt could physically alter her unborn child. In one remarkable tale, a newspaper reported that an alleged father's name "appear[ed] in legible letters in his infant son's right eye" [sources: Encyclopaedia Britannica; Davis; Pediatrics; University of Glasgow].

Clearly, argued consulting experts, poor Mary Toft had suffered a startling, rabbit-related encounter that had transformed her into a bunny-birthing dynamo.

Toft carried off the hoax for months, enjoying national celebrity, fooling numerous physicians and attracting the attention of King George I. A few experts, like German surgeon Cyriacus Ahlers, offered discrediting scientific evidence, noting that some "newborn" dead rabbits had air in their lungs and stool containing straw, grass and grain. But it was not until someone caught her mother-in-law hare-handed buying small rabbits, and under threat of painful reproductive exploratory surgery, that Mary confessed [sources: Encyclopaedia Britannica; Davis; Pediatrics; University of Glasgow].

3: Blood Will Out ... Eventually

Our ideas about blood and how it works have evolved quite a bit over the centuries.
Our ideas about blood and how it works have evolved quite a bit over the centuries.

If 18th-century physiology was such a mess, you can imagine how early medicine must have played out. On the one hand, access to dissection subjects drove great advances in anatomy and physiology as far back as 300 B.C.E. On the other hand, every correct conclusion seemed counterweighted by superstition and social prejudice.

Greek physician Praxagoras (fourth-century B.C.E.) differentiated veins from arteries, but thought arteries carried air (likely because corpse arteries are often empty). In the second century, Galen carried on this tradition, but added that blood was made in the liver, which he said imbued it with "natural spirit," and swirled around the body in veins. It did not pump so much as it sloshed. Once it mixed with "vital spirit" from the lungs, blood was consumed by organs, which "attracted" it the way lodestone attracts iron. Blood also reached the brain via hollow nerves, he said, where it absorbed "animal spirit" [sources: Aird; Galen; West].


These notions held on until William Harvey published his game-changing "On the Motion of the Heart and Blood in Animals" in 1628. Others, such as Arab scholar Ibn an-Nafis, who died in 1288, had earlier made several corrections, but the Western world remained unaware of his work. Another predecessor, Spanish physician Miguel Serveto described circulation correctly in the 16th century, but wrapped his findings in a religious screed which, like Serveto himself, ended up burned on a pyre [sources: Aird; Cambridge Modern History; West].

2: Aristotle's Take on Physics

A print from 1561 of a gunner firing a cannon. The path of the projectile is shown according to Aristotelian physics.
A print from 1561 of a gunner firing a cannon. The path of the projectile is shown according to Aristotelian physics.
Ann Ronan Pictures/Print Collector/Getty Images

When Galileo demolished geocentrism, he also tore down several other cherished (but wrong) Aristotelian views. Aristotle explained motion by asserting that all matter had a proper place to which it tried to return, and that heavier objects should fall faster than lighter ones. But through meticulous experimentation, Galileo showed that objects falling or rolling downhill accelerate at the same constant rate, which we call acceleration due to gravity [sources: Alioto; Dristle].

Aristotle had also argued that a moving object in its natural place, such as a ball rolling along the ground, would gradually stop because it was its nature to stay there. But as Galileo realized, and as Newton later formalized, the apparent slowing of moving objects was caused by friction; take that away, and a ball would roll on forever [sources: Alioto; Dristle; Cardall and Daunt; Galileo].


Along similar lines, the Aristotelian-Ptolemaic view of physics implied that a piece of shot dropped from a ship's crow's nest would land some distance behind the mast because the ship moved forward while the ball fell. But Galileo showed that the cannonball, which shares the ship's forward velocity, would actually fall straight to the base of the mast. In these ways, Galileo, one of the fathers of experimental science, prefigured Newton's laws of motion, as well as the concept of reference frames while also disproving some of the chief arguments against Earth's movement [sources: Cardall and Daunt; Galileo].

1: Bloodletting as a Legit Medical Cure

Leeches are so old school – or not.
Leeches are so old school – or not.
© Tony Savino/Corbis

No survey of the crazy things we believed before the scientific method would be complete without some mention of the weird and horrifying practices we once considered medicinal.

Remember all that business about humors (blood, phlegm, black bile and choler, aka yellow bile)? Well, imagine what kind of medical treatments might arise from such a bodily fluid-focused approach, and you have a sense of what humoral medicine was like: diagnoses based solely on the smell of feces, urine, blood or vomit; physicians who prescribe forced vomiting, frequent bloodletting and iffy enemas to balance the body out. What it lacked in effectiveness it made up for in sheer life-threatening danger. Not surprisingly, people stuck to prayer and folk remedies whenever possible [sources: Batchelor; Getz].

As for bleeding hemorrhoids, some doctors viewed them as natural humor-balancers, useful for relieving mania, depression, pleurisy, leprosy and dropsy (edema). Of course, if bleeding got out of hand, it was time to break out the red-hot pokers. It's amazing what people will sit still for [sources: Encyclopaedia Britannica; Encyclopaedia Britannica; DeMaitre].

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Author's Note: 10 Things We Thought Were True Before the Scientific Method

All theories rest, to some degree, on assumptions. We try to minimize them, because they make up hidden cracks in science's foundations but, short of actual omniscience, they're pretty much unavoidable.

When a theory falls apart, it's often because an assumption was wrong. Science is always an educated best guess, after all -- it's just that, under modern scientific method, we subject those conjectures to rigorous tests through prediction, observation, repeatable experiments and peer review. Because of this, even when we're off the beam, we aren't far off and, in any case, it's only temporary. Einsteinian physics replaced Newtonian, but Newton's laws still work in every situation we typically encounter in our lives, so we still use them. If, someday, someone supersedes Einstein, it will only be in some limited sense (replacing an underlying assumption or mechanism, likely). Einstein's predictions simply work too well to be wholly wrong.

And in the end, that's the point. Science is what works.

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