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I've heard it numerous times, that in the old days people thought that the world was flat. Most commonly I heard this in connection with the voyage of Columbus, that he believed the earth to be a sphere while most other people thought he must fail to reach India as the world is flat.

Is there any direct evidence, e.g. written documents, that shows since when people knew that the earth is a sphere? And since when was this common knowledge in the educated population?

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Regardless of what people used to think, these guys are apparently for real... –  David Hedlund Mar 7 '11 at 7:46
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Can't find any credible references, but I believe it was generally known that the earth ws round, especially when people saw boats disappear behind the horizon etc. How widespread which believe was is a bit harder to substantiate. might look into it later ;D –  Nanne Mar 7 '11 at 7:53
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@David: No, the flatearth society isn't for real. Those are people who argue the position for fun. –  Christian Mar 7 '11 at 11:25
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See en.wikipedia.org/wiki/Myth_of_the_flat_earth which is about exactly this (the myth that a belief in a flat earth existed). Feel free to improve. –  ShreevatsaR Mar 14 '11 at 14:21
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@Christian see Poe's law "Without a winking smiley or other blatant display of humor, it is impossible to create a parody of fundamentalism that someone won't mistake for the real thing." –  Sam I Am Mar 30 '12 at 3:57
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According to Dr Karl, it was known that the earth was a sphere as far back as Aristotle. The three reasons were:

  • The top of the mast being sighted before the rest of the ship
  • Lunar eclipses always throwing a circular shadow
  • The rising of the high point of certain constellations as one travels further south

The scientists thought Columbus's voyage would fail, not because they thought the earth was flat, but rather because he would have to travel 20000 nautical miles, rather than 5000.

So, for the last 2500 years, in Europe and in the Middle East, the flat-earthers were in a very small minority. At least, this is what the historian Jeffrey Burton Russell, of the University of California at Santa Barbara, reckons.

His book, In Inventing the Flat Earth, claims that since the third century BC, practically all educated people in the western world believed in a spherical earth.

Looking as a historian into the historical record, he found tens of thousands of Christian theologians, poets, artists and scientists who believed that the earth was a sphere.

On the other hand, he could find only five Christian authorities who believed in a flat earth.

The Straight Dope also discussed this.

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"...practically all educated people in the western world..." However the majority of people in the western world at that time were most likely not educated. –  morganpdx Mar 7 '11 at 18:40
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"However the majority of people in the western world at that time were most likely not educated." And never considered the question at all because it was utterly irrelevant to their existence. They didn't "believe" in a flat or a round earth, they just knew there was a place they lived and grew their crops, a place occasionally hit by disasters they had no power over. –  jwenting Mar 8 '11 at 8:33
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And Columbus' voyage would have failed, were it not for the New World being in the same spot where Columbus thought he would find Asia. –  dan04 Mar 17 '11 at 5:40
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The use of an orb with a cross (globus cruciger) at the coronation of Christian monarchs for the last 1600 years is evidence that both the religious and the secular state thought the world was a sphere. Images of this (e.g. on coins) would have spread the idea to the less educated. –  Henry Mar 24 '11 at 16:46
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Also, Dante's Divine Comedy, written 1308-1321, provides a complete Medieval cosmology based on the Ptolemaic model. It includes a round Earth, with Hell at the center. –  Charles Salvia Jun 14 '11 at 2:12
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According to historian James Hannam, the trope that the people in the Middle Ages believed that the Earth was flat was created in the 19th Century.

It is not difficult to see how the story of Columbus was adapted so that he became the figure of progress rather than a lucky man who profited from his error. According to Jeffrey Burton Russell here, the invention of the flat Earth myth can be laid at the feet of the nineteenth century writer Washington Irving, who included it in his historical novel on Columbus, and the wider idea that the everyone in the Middle Ages was deluded has been widely accepted ever since.

The Real Flat Earthers

The myth that Christians in the Middle Ages thought the world was flat was given a massive boost by Andrew Dickson White's weighty tome The Warfare of Science with Theology published in 1896. This book has become something of a running joke among historians of science and it is dutifully mentioned as a prime example of misinformation in the preface of most modern works on science and religion. The flat Earth is discussed in chapter 2 and one can almost sense White's confusion that hardly any of the sources support his hypothesis that Christians widely believed in it. He finds himself grudgingly admitting that St Clement, Origen, St Ambrose, St Augustine, St Isodore, St Albertus Magnus and St Thomas Aquinas all accepted the Earth was a globe - in other words none of the great doctors of the church had considered the matter in doubt. Although an analysis of what White actually says suggests he was aware that the flat Earth was largely a myth, he certainly gives an impression of ignorant Christians suppressing rational knowledge of its real shape.

Here is the link that Hannam is referring to. In it Jeffrey Burton Russell writes:

In my research, I looked to see how old the idea was that medieval Christians believed the earth was flat. I obviously did not find it among medieval Christians. Nor among anti-Catholic Protestant reformers. Nor in Copernicus or Galileo or their followers, who had to demonstrate the superiority of a heliocentric system, but not of a spherical earth. I was sure I would find it among the eighteenth-century philosophes, among all their vitriolic sneers at Christianity, but not a word. I am still amazed at where it first appears.

No one before the 1830s believed that medieval people thought that the earth was flat.

The idea was established, almost contemporaneously, by a Frenchman and an American, between whom I have not been able to establish a connection, though they were both in Paris at the same time. One was Antoine-Jean Letronne (1787-1848), an academic of strong antireligious prejudices who had studied both geography and patristics and who cleverly drew upon both to misrepresent the church fathers and their medieval successors as believing in a flat earth, in his On the Cosmographical Ideas of the Church Fathers (1834). The American was no other than our beloved storyteller Washington Irving (1783-1859), who loved to write historical fiction under the guise of history. His misrepresentations of the history of early New York City and of the life of Washington were topped by his history of Christopher Columbus (1828). It was he who invented the indelible picture of the young Columbus, a "simple mariner," appearing before a dark crowd of benighted inquisitors and hooded theologians at a council of Salamanca, all of whom believed, according to Irving, that the earth was flat like a plate. Well, yes, there was a meeting at Salamanca in 1491, but Irving's version of it, to quote a distinguished modern historian of Columbus, was "pure moonshine. Washington Irving, scenting his opportunity for a picturesque and moving scene," created a fictitious account of this "nonexistent university council" and "let his imagination go completely...the whole story is misleading and mischievous nonsense."

You can see Aquinas - who lived in the 13th Century - referring to the sun lighting up the "hemisphere" at Question 67 of the Summa Theologica, which is evidence that it was a commonplace understanding that the Earth was a sphere at that time. [Interestingly, Aquinas disputes that light is a body on the grounds that the movement of light cannot be discerned at large distances. His reasoning is impeccable; his measuring instruments were insufficient; his conclusion was wrong.]

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I find this source highly suspect. In the article guardian.co.uk/commentisfree/belief/2009/oct/22/… (titled 'How catholics must fight back'), he makes his pro-religion and pro-catholic stance very clear. A quote from the link used in the article I obviously did not find it among medieval Christians. Notice how the word obvious is used. The quoted text is mainly aimed at showing how pro-science the Church and Christians have been. For this reason, I think the source is inherently biased. –  apoorv020 Apr 21 '11 at 14:49
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As for Aquinas, I think "the whole hemisphere" relates to the apparent skydome hemisphere. I cannot see how words the lighting of the earth hemisphere could be used as an example of light being instantaneous. It seems just to describe that in the very moment the sun raises on east, even the west part of sky is lit. –  Suma Apr 22 '11 at 8:17
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Hannam is a Catholic and a historian. Because of his religious perspective, he takes the time to vet statements and claim that have made their way into the modern culture, which in English-speaking countries tends to be hostile to the Catholic contribution to history, and which is prepared to believe nonsense like "people believed the world was flat." Hannam is, therefore, balance - the skeptic viewpoint - to the conventional wisdom. –  Peter Sean Bradley Apr 23 '11 at 18:57
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As for Aquinas, what he was referring to was that light appeared to be instantaneous because it lit up the entire "hemisphere." In Aquinas Question 67, Aquinas may be talking about the hemisphere of the sky, but it isn't clear that he isn't referring to the hemisphere of the Earth. In Question 54 of the First Part of Second Part, Article 2, reply to objection 2, Aquinas clearly refers to the earth being round. newadvent.org/summa/2054.htm#article2. See also 1a, Q 1, a1, newadvent.org/summa/1001.htm#1. The clear point being that Aquinas recognized the Earth was round. –  Peter Sean Bradley Apr 23 '11 at 19:09
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@apoorv020, perhaps he's biased, perhaps he's not. It doesn't actually matter. The question is whether he shows his sources. If he does, then it doesn't matter whether he's "biased". Either there's evidence to contradict him or there's not. –  Kyralessa May 1 '11 at 13:34
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Eratosthenes (276–195 BCE) is famous, among other things, for calculating the circumference of the Earth – which of course implies that the knowledge about Earth’s shape was available in his days.

In fact, his method of measuring Earth’s circumference is routinely taught in school today1 so it’s a bit surprising how many people still think that people in the middle age believed Earth to be flat.


1 At least in France and Germany it’s part of the standard curriculum of physics.

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Devil's advocate: just because person X knew the Earth is round in 200 BCE, doesn't mean that everyone and his grandma knew the same in the middle ages. (Or know it today, for that matter.) Concrete and steam engines were invented thousands of years ago, too, but then the knowledge was lost for many, many centuries, and they had to get re-invented all over again. –  RegDwight Mar 7 '11 at 20:31
    
@Reg: true that. I wanted to add that his method of computing the circumference was widely hailed at the time (i.e. that it was widely known and acknowledged to work) but I couldn’t find a good source. –  Konrad Rudolph Mar 7 '11 at 20:34
    
Aristosthenes also believed that the Earth revolves around the sun along with the other planets, and it seems likely to me that Appolonius even understood that the orbits were elliptical with an area law (or at least off-center circles). This stuff was lost, probably due to the Bible's insistance on Babylonian cosmology. The Bible also insists that the Earth is flat, although this is easier to hide. the fact that ancient people knew stuff doesnt mean mideval people did. –  Ron Maimon Mar 27 '12 at 6:07
    
@Ron I’d like to see some good references on that one. Furthermore, even if Aristotles believed that his evidence may have been sketchy. While certain inferences about the orbits could be made by observing the stars, I think civilisation of Antiquity lacked fundamental pieces (both in understanding & technology, e.g. good telescopes) to make informed claims about this. In summary, I don’t think these two situations are comparable. Furthermore, if “that stuff was lost” how do you know about it? Was it re-discovered later? –  Konrad Rudolph Mar 27 '12 at 10:40
    
@KonradRudolph: The evidence for Aristarchus (sorry, not Aristosthenes, I mixed them up) knowing the Earth revolves around the sun is from Archimedes surviving "Sand Reckoner", where he uses this idea as the default position, in a way that strongly suggests he supports it. Appolonius and Archimedes were contemporaries working on similar things, and Appolonius develops the epicycle/equant system, which is known to be an Earth-centered approximation to an off-center circle (or ellipse) which is cited by Ptolmey in the Almaghest (Appolonius's work on this is destroyed). –  Ron Maimon Mar 29 '12 at 4:15
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There is an essay by the late Stephen Jay Gould, “The Late Birth of a Flat Earth”, that discusses this very question. In a nutshell, Gould traces back the myth that people in the Middle Ages thought the earth was flat to a 19th-century origin in the form of a fabricated textbook passage. The text is included in Gould’s 1995 collection of essays, Dinosaur in a Haystack.

Gould recounts a reconstruction of the flat-earth myth from a book by historian J.B. Russell, who traces the myth back to two 1870s books, by John Draper and Andrew D. White (founder of Cornell University), respectively, which argued for a continual, and ultimately winning, struggle of reason and science against the obscurantism of the Church. But, as Gould vividly explains, scholars from the Venerable Bede to Roger Bacon and Thomas Aquinas took a spherical earth entirely for granted. The upshot: neither Dark nor Middle Ages were quite as benighted as some stories would have them.

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Welcome to the site!. Can you please provide a brief excerpt? –  Sklivvz Mar 29 '12 at 21:19
    
@Sklivvz: Gould recounts a reconstruction of the flat-earth myth from a book by historian J.B. Russell, who traces the myth back to two 1870s books, by John Draper and Andrew D. White (founder of Cornell University), respectively, which argued for a continual, and ultimately winning, struggle of reason and science against the obscurantism of the Church. But, as Gould vividly explains, scholars from the Venerable Bede to Roger Bacon and Thomas Aquinas took a spherical earth entirely for granted. The upshot: neither Dark nor Middle Ages were quite as benighted as some stories would have them. –  Peter Beattie Mar 30 '12 at 0:56
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@Peter That comment should be part of the answer. ;-) –  Konrad Rudolph Mar 30 '12 at 14:27
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@Konrad: Well, now it is. :P –  Peter Beattie Apr 2 '12 at 14:03
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About the fact the (educated) Middle Age people knew well that the Earth is spherical, let me add that the Earth Dante had in mind was indeed spherical, and in his Divine Comedy he describes precisely the moment in which, when he reaches the bottom of the Inferno, which is an enormous conical empty space having its vertex in the centre of the Earth, Dante goes through the centre of gravity of the planet and his "up" become his "down":

The Guide [Virgil] with labour and with hard-drawn breath
Turned round his head where he had had his legs,
And grappled to the hair [of Satan, who stands at the centre of the Earth], as one who mounts,
So that to Hell I thought we were returning.

(Inferno, XXXIV, 78--81, translation by Longfellow; see also the following lines).

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This demonstrates that one writer knew of the concept in the 14th Century, enough to inspire a fictional work. Doesn't mean he believed it. Doesn't mean others did or didn't. Doesn't answer the question. –  Oddthinking Nov 29 '11 at 2:41
    
My answer, of course, doesn't "demonstrate" anything. Studying Dante's work and times does. The relevant literature is not exactly small: is this the right place to give it? –  DaG Dec 4 '11 at 16:21
    
If by "literature" you mean more English literature (as opposed to scientific literature) then I haven't managed to make my point, sorry. I am complaining about the quality of the literature, not the quantity. By analogy, I could produce a large quantity of literary texts that showed that, at the beginning of the 21st Century, people believed that a zombie invasion was imminent. Finding fictional work that mentions an idea doesn't mean many people are exposed to it or that many people believe it to be true. It doesn't even show the author believes it to be true. –  Oddthinking Dec 4 '11 at 22:15
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@Oddthinking, Dante's aim was that to provide a unified view and a real and vivid description of heaven, purgatory and hell to the common man. While he clearly writes fiction, he is doing so with a pedagogic intent (similar to what Galilei does in the "Dialogue"). It is not exactly the same as zombie novels... –  Sklivvz Apr 2 '12 at 22:34
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@Oddthinking see: en.wikipedia.org/wiki/Divine_Comedy#Scientific_themes –  Sklivvz Apr 2 '12 at 22:36
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Myth of the Flat Earth I found this to be a very good source

We all know that Christopher Columbus encountered stiff resistance about his idea of sailing off West to try and reach the East Indies. Many of us have laboured under the impression that people were concerned that he would sail off the edge of the Earth which was widely believed to be flat. History is thought to have vindicated Columbus against those filled with the Christian superstition of a flat Earth who held on to old fashioned beliefs. A minority of people are even under the impression that Galileo's trial centred on the subject rather than whether the Earth orbited the sun.

It comes as some surprise, therefore, to find that Columbus was wrong and his critics were right - not because the world is actually flat after all, but because at the time everyone knew it was a globe and were arguing about how big it was. The idea that the uncouth people of the Middle Ages thought the Earth was flat is an example of the myth that has been propagated since the nineteenth century to give us a quite unfair view of this vibrant and exciting period."

[...]

In particular a committee set up in Salamanca examined the plans and rejected them on the grounds that Columbus had underestimated the distance he would have to travel.

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Yes Columbus was wrong in his calculus while other detractors were right. But he discovered a new continent (though he thought it was India). Maybe we need stupid people that will undertake what intelligent ones will not dare. –  Nikko Apr 2 '12 at 15:54
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http://en.wikipedia.org/wiki/Eratosthenes

My man Carl Sagan tipped me off to this one in the Cosmos. If you haven't seen it, go watch it now! Youtube! Free and available to everyone because he was a beast!

I do think it was a generally accepted concept among those who cared to think about it before Eratosthenes, but he gets the credit for proving it.

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Welcome to Skeptics Stack Exchange! Please provide some better references to support your answer: certainly Eratosthenes is not representative of the general belief at the end of the middle ages. –  Sklivvz Mar 6 at 21:25
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