Richard Thaler’s question

by on November 22, 2010 at 11:09 pm in History, Science | Permalink

I am doing research for a new book and would like to hope to elicit informed responses to the following question:

The flat earth and geocentric world are examples of wrong scientific beliefs that were held for long periods. Can you name your favorite example and for extra credit why it was believed to be true?

Please note that I am interested in things we once thought were true and took forever to unlearn. I am looking for wrong scientific beliefs that we've already learned were wrong, rather than those the respondent is predicting will be wrong which makes it different from the usual Edge prediction sort of question.

There are many answers here (scroll down).  Hat tip goes to Edge on Twitter.

1 John November 22, 2010 at 7:22 pm

Agh! I always wince when I see this. People knew with certainty that the earth was a sphere by 3rd century BC, although even in the fifth century BC Plato and Aristotle taught their students the Earth was a sphere. Since geometry is sort of a prerequisite for a coherent belief about the shape of the earth, it really didn't take long after geometry was invented to get there.
http://en.wikipedia.org/wiki/Spherical_Earth

2 PeterW November 22, 2010 at 7:28 pm

A relevant article: http://bellagerens.com/2010/05/15/two-degrees-of-

"Ancient cosmology, like Aristotelian physics, has become a modern archetype for ‘wrong’ science, primarily because in our present-day arrogance we have applied Occam’s razor retrospectively and concluded that those old astronomers were idiots. But this is tremendously unfair, because actually the ancients weren’t wrong, at least not in the sense we usually mean….

You can’t exactly blame [them], can you? To the naked-eye observer, it really does look as if the Earth stands still and everything else circles around it. We, who are so big on Occam’s razor, can hardly criticise the ancients for assuming this simplest of theories was the correct one. They saw what appeared to be the skies circling round the Earth. There was no good reason, at the time, to question this simple and elegant explanation of observed conditions.

Unfortunately, that simple starting point made it exponentially difficult to explain the mechanisms empirically or prove them mathematically. Every time someone thought they’d figured out the process, their predictions would turn out to be wrong – even if just a little – and then it was back to the drawing board to add on new layers of theories to account for those errors. Nobody thought to go back and examine point A, because why would they? Like good little scientists, they assumed the data were correct and the mistakes were theirs. They didn’t consider that stationary geocentrism was not a datum at all. So the tiny fixes for the tiny errors built over time into a giant, interdependent, Escher-like edifice that was always just not quite right, a kaleidoscope picture just out of true no matter how one fiddled with it."

3 John November 22, 2010 at 7:37 pm

"So the tiny fixes for the tiny errors built over time into a giant, interdependent, Escher-like edifice that was always just not quite right, a kaleidoscope picture just out of true no matter how one fiddled with it."

We should bear in mind that this is true of our present theories of astronomy and cosmology as well… 'dark matter' anyone?

4 Peter Vardon November 22, 2010 at 7:45 pm

Bloodletting was practiced for 2000 years

http://en.wikipedia.org/wiki/Bloodletting

5 moom November 22, 2010 at 8:16 pm

According to Wikipedia the lactic acid story is more complicated than that:
http://en.wikipedia.org/wiki/Lactic_acid

6 xysmith November 22, 2010 at 8:28 pm

Newtonian physics. It's believed because it works most of the time.

7 Eli November 22, 2010 at 9:09 pm

Keynesianism, duh.

8 Evan November 22, 2010 at 9:18 pm

Bloodletting was practiced for 2000 years
http://en.wikipedia.org/wiki/Bloodletting

Posted by: Peter Vardon at Nov 22, 2010 11:45:01 PM

Bloodletting is still used! Although, to be fair, its use is certainly based in much sounder science these days, such as for the treatment of heamachromatosis.

9 Six Ounces November 22, 2010 at 9:39 pm

How long did it take primitive man to figure out that sex caused pregnancy?

After all, cause and the first observations of the effect are separated by several months. And at that point there's no reason to believe the sexual act caused the swollen "stomach."

At birth, one can observe the child being born through the same orifice that intercourse took place, but now cause and effect are separated by 9 months.

"They know what causes that now." – Hawkeye Pierce.

10 Andrew Smith November 22, 2010 at 9:45 pm

@john, not only did the ancient Greeks know the Earth was round, they knew how big it was: http://en.wikipedia.org/wiki/Eratosthenes

11 Heridfel November 22, 2010 at 10:17 pm

Actually, one of the long-held erroneous beliefs is our still-current belief that belief in a flat earth was the norm until the Renaissance. In reality, knowledge that the earth was a sphere never went away since antiquity.

12 Six Ounces November 22, 2010 at 10:25 pm

It took about 3100 years from the first known textual reference to π (ancient Egypt) until the first time anyone asserted that it was an irrational number (Maimonides).

It took another 500 years before anyone is known to have proven it (Lambert).

13 anonymous November 22, 2010 at 11:03 pm


And despite knowing better, we still often use these simpler approximations.

Sure. And we still use the flat-earth theory when we calculate the surface area of a football field as exactly 360 × 130 square feet, instead of applying spherical trigonometry.

14 Tracy W November 22, 2010 at 11:41 pm

My favourite wrong scientific hypothesis is that sex causes pregnancy. It doesn't, at least not directly. A fertile cell, implanted in the womb wall, causes pregnancy. One can have sex without this happening, and some contraceptives work by reducing the probability of it happening, or one can have a fertile cell implanted without having sex – by IVF. If the cell implants itself successfully, then the woman's body can take it from there.

15 Sergey Kurdakov November 23, 2010 at 1:13 am

In Economy maybe belief that Mises/Ropthbard/Hoppe approach has any ground ( see Quine on synthetic apriory truths and Shiller in Formal logic on if logic can be of any help without context ). Still there are people ( including your colleague Boettke ) who think that there is something 'clever' in devising 'truths' and then making logical conclusions rejecting any notion of checking the relevance of context. It is still with us – and this awful thing, because works of both Quine and Shiller are not such new, with computer specialists having difficulties with logical but absurd conclusions made by programmed AI without context.

16 Chris R November 23, 2010 at 1:27 am

I'd put the whole premise of the article into the bin "wrong beliefs that were held for long periods". That we're intrinsically smarter or better than the ancients–that they were dumb enough to believe that the earth was flat for instance. That human nature has shown constant improvement and improvability over time. That a modern "scientific" diet of starches and sugars is intrinsically superior to an ancient one of meat, fish, and vegetables. Pretty much scientism and progressivism and overengineering in general.

17 UpHere November 23, 2010 at 2:08 am

Thaler's writing a book about EMH? I always found it entertaining that tomatoes were considered poisonous during the Middle Ages because they were. They were leeching lead out of the dinner plates.

18 Borealis November 23, 2010 at 2:23 am

One ongoing myth is that a President can be measured by some indicator (GDP, employment, high school graduation rate, etc.) from the day he took office to the day he left office. What possible effect could a President have that begins on inauguration? Almost all debated policies are designed to have effects years or decades after enactment.

19 UpHere November 23, 2010 at 3:14 am

Dearieme: thanks for the correction. I'm reasonably confident in the info but I must have been a few hundred years off.

20 Ironman November 23, 2010 at 3:41 am

For an example neither yet on this or Thaler's list:

The Piltdown Man hoax – the direct forerunner to key aspects of today's climate science scandal. It was first believed to be true because of falsified evidence, then continued for decades thanks to a combination of national and institutional "emotional investment" in the so-called "evidence," which acted to obstruct a definitive debunking from occurring much sooner.

21 Nate November 23, 2010 at 4:02 am

The belief that saturated fat causes heart disease. See Good Calories, Bad Calories for a history on how this came to be.

22 RHD November 23, 2010 at 5:02 am

The idea that MSG is bad for you… Well, maybe it's bad for some people, like anything else… http://en.wikipedia.org/wiki/Monosodium_glutamate

23 Jeffrey Winter November 23, 2010 at 5:18 am

For years it was a given fact that humans had 24 chromosomes; e.g., as late as 1954, cytologist L. Sachs stated, "the diploid choromosome number of 48 in man can now be considered as an established fact."

But in 1956, Joe Hin Tjio and Albert Levan discovered that there were in fact only 23 chromosomes. They even went back to look at old photographs in books and counted 23 pairs even though the captions said there were 24.

From their paper: "For instance, we think that the excellent photomicrograph of Hsu published in Darlington's book (1953) is more in agreement with the chromosome number 46 than 58, and the same is true of many of the photomicrographs of human chromosomes previously published."

Joe Hin Tjio, Albert Levan. The Chromosome Number of Man. Hereditas; Vol., Issue 1-2, pages 1–6, May 1956.

The "established fact" was making scientists blind to what was before their eyes.

24 William McGreevey November 23, 2010 at 5:27 am

Just a fill-in on the successful appearance of germ theory of disease: Miasma, or odors floating up as the stench of sewers, were for long blamed for illness. So now it's not 'the nose knows,' but 'the nose thought it knew but didn't.'

25 AaronM November 23, 2010 at 5:57 am

As I was scrolling down, I was hoping that no one would mention the concept of “aether,” so that I might be the first. But Russell1000 beat me to it. It’s a pretty good example in that it was postulated in order to support the prevailing worldview at the time – that there exists an absolute frame of reference which is “at rest,” against which all motion can be measured. Relativity did away with this.

If my memory serves me correctly, the aether substance in the interstellar space was believed to be necessary for rocket propulsion of any sort, since without aether there would be nothing for the rocket to “push against.” This conception always struck me as bizarre, since simple Newtonian physics is enough to demonstrate its falsehood.

In the realm of chemistry, the concept of vitalism persisted for an extended period – the notion that some “life force” was necessary to produce organic chemical compounds, which were fundamentally different from inorganic compounds. Friedrich Wöhler provided the scientific rejection of this by synthesizing urea in 1828, but others (including Pasteur) continued to hold fast to vitalism for decades afterwards.

I can imagine how such a belief might derive from our propensity to want to believe in our own specialness, as living beings.

My favorite example from the modern times is the alleged role of immunizations in producing autism, which many people still believe strongly. The reasons for the persistence of this belief are clear; the same people that espouse this falsehood to parents of autistic children often offer them the (equally unfounded) possibility of treatment and cure. Beyond those directly affected by autism, the persistence of this idea speaks to the public’s lack of ability to understand scientific data; multiple large, controlled trials showing absolutely no connection between vaccines and autism are outweighed in the public’s mind by concerned parents “raising questions.”

Perhaps this idea has not yet persisted for a long period. However, I would say that given failure of scientific consensus to resolve this issue, it should still qualify.

I also remember reading in the solar system chapter of a grade school science textbook printed in the 1940s, that, in reference to our telescopic imaging of Mars, “we know something is alive there, and we know that it is growing.” Upon further reading, it seemed that the authors’ conception of Martian life included macroscopic flora, at least. I found this particularly interesting, since (in my relative youth) I had always imagined that a scientifically-based, rather than speculatively-based, conception of extraterrestrial life (the Drake equation, etc) was a more recent phenomenon. Furthermore, I would have expected the discovery of extraterrestrial life to be problematic to many of us Earthlings, inclined as we are to believe in our own significance; yet, apparently the “knowledge” of Martian life was so commonplace in the early 20th century that it made it into school textbooks without much of a stir.

26 J Thomas November 23, 2010 at 6:05 am

"Just a fill-in on the successful appearance of germ theory of disease: Miasma, or odors floating up as the stench of sewers, were for long blamed for illness. So now it's not 'the nose knows,' but 'the nose thought it knew but didn't.'"

Has it been established that you cannot get intestinal diseases by sniffing sewers?

27 Pavel Kohout November 23, 2010 at 6:05 am

Central planning, anyone?
Phrenology?

28 bjartur November 23, 2010 at 7:02 am

That we can (even roughly) predict when we will run out of a natural resource based on knowledge of the historical trend in consumption and the amount of the resource known or thought to exist at the time of the prediction.

29 wintercow20 November 23, 2010 at 8:47 am

The age of the Earth and Sun? In the 19th century, the known processes of combustion told scientists that the sun could not have been burning for more than a few hundred million years. Yet, fossil and rock evidence on earth suggested that the Earth was much older than that.

Then someone stumbled upon the power of the atom.

30 Gib Bassett November 23, 2010 at 9:58 am

Bode's Law.

If it works out of sample it must be true.

31 kb November 23, 2010 at 10:44 am

i thought lee smolin's response to thaler's question to have the most interest for MR readers

"Since then some of the more interesting work in economics studies issues of path dependence and multiple equilibria.

I cannot comment on why economists made the mistake of thinking about market equilibrium as if it were unique."

32 Dan H. November 23, 2010 at 11:42 am

Aerodynamic lift is a good candidate.

Children are still taught in school that lift is caused because the air going over a wing has to go faster because the top surface is curved, so distance the air has to travel over the top is further than that of the air going below the wing. The result is that the molecules on the top are forced to spread out, resulting in lower pressure on the top than on the bottom. The plane is then pushed up by that pressure.

This is usually accompanied by a nice picture of air flowing over the top and bottom of the wing, meeting up at the back, and then proceeding along its original path undisturbed.

In fact, pilots are still taught this. And many undergrad textbooks still explain it this way.

It's completely wrong. In fact, the lift generated by a wing is the result of Newtonian forces – the wing pushes air down behind it (the downwash), and the force required to push the air down causes an opposing force pushing the airplane up. The curvature of the top surface causes the air to change direction and take on a downward vector as it comes off the back of the wing. Those pictures of a wing showing the air flowing off the back undisturbed show a wing that is not creating lift.

The other part of the lift equation is the angle of attack of the wing, which also causes air molecules to hit the underside of the wing and bounce of it, creating 'flat plate lift' like the force you feel when you stick your hand out of the window of a car.

It's easily demonstrated that the molecules on the top and bottom of a wing do not meet up at the back at the same time, and this has been known since pretty much the Wright Brothers. Yet the 'equal transit time' theory is still taught. Bizarre.

The other main candidate would be evolution. The evidence for it is overwhelming and incontrovertible, yet billions of people on the planet refuse to believe it.

33 Doc Merlin November 23, 2010 at 12:17 pm

Galileo is another great example of wrongness. His calculations for the orbits based on fixed, circular, heliocentric orbits were far more inaccurate than the ones based on epicycles and heliocentric theory.

34 George Schoeneman November 23, 2010 at 12:42 pm

Until the late 19th century, pain was considered to be an integral part of healing; it was the body fighting for life. Thus, not only was anesthesia not researched, known anesthetics were refused to suffering patients. I'm glad they got this one right before my time!

35 Steko November 23, 2010 at 1:16 pm

whatever talk radio host with no scientific credentials told commenter to not believe in, duh

36 Right Wing-nut November 23, 2010 at 1:33 pm

How could I forget?

7) There are four fundamental tastes. (Fit in with the four elements.)

37 Norman November 23, 2010 at 5:42 pm

[…]wasn't there an extended period (early middle ages, maybe 500-1000AD?) during which the Catholic Church taught that it was flat, based on a literal interpretation of biblical texts?[…]
Posted by: bbartlog at Nov 23, 2010 7:29:15 AM

@bbartlog, actually the medieval Catholic Church taught royalty and its priests (the only people in Europe to receive advanced education at the time) from Aristotle, so educated people at the time also knew the earth was a sphere. Illiterate subsistence farmers may have believed differently, but then illiterate subsistence farmers may believe differently even today.

There was, however, a time in the 19th century when author Washington Irving wrote that medieval Catholics believed the earth was flat. He wanted to make those who opposed Darwinism on religious grounds appear ridiculous, and was wildly successful, despite completely fabricating the story.

So, ironically, the bigger false belief is actually held by those who still attribute to medieval Catholics this particular false belief!

History of Science is an under-recognized discipline.

38 Chris Durnell November 24, 2010 at 6:45 am

The myth that Europeans thought the Earth was flat before Columbus has its origins in a story by Washington Irving. It has no basis in reality. As far as I know, it was never dogma of the Catholic Church that the earth was flat. Clement, Origen, Ambrose, Augustine, Isodore, Albertus Magnus and Aquinas all accepted the Earth was a globe. Some people thought the Earth was flat, but it was a distinct minority view among the intellectual elite that was usually ridiculed. When Columbus debated in Salamanca about his voyage to the west, it was not over the shape of the Earth, but its distance. In truth, Columbus was wrong about the distance and his opponents were right since Asia was far further away than Columbus thought.

Other proof that people in the Middle Ages knew the Earth was flat can be seen in royal insignia. Kings held both a sceptre and an orb (the globus cruciger). The orb represented dominion over the Earth. In other words, a sphere represented the world. If people didn't think the world was a globe, why would they have depicted it as such?

That sailing ships would slowly disappear over the horizon was fairly self-evident proof that the surface of the Earth was curved, hence a sphere. This was evidence available to anyone at any time. The work of Eratosthenes was not so much to prove the world was round, but to determine its circumference.

39 Shane M November 26, 2010 at 5:49 pm

From Quantum mechanics, that reality doesn't exist independently of our observation of it. Or maybe Einstein was right about that one….

40 Susan Wilhite November 28, 2010 at 9:08 pm

Superheater mentioned mine – Alchemy. But where it wasn't punished we got a grounding in materials science and medicine.

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