Friday, February 27, 2009

Columbus and the 'Flat Earth'

Columbus : The earth is not flat, Father, it’s round!
The Prior : Don’t say that!

Columbus : Its the truth; it’s not a mill pond strewn with islands, it’s a sphere

The Prior : Don’t, don’t say that; it’s blasphemy

Dialogue from 'Christopher Columbus', A Play by Joseph Chiari

In a momentous passage from book 2 of ‘On the Heavens’, Aristotle concludes that the earth is spherical:

Either then the earth is spherical or it is at least naturally spherical. And it is right to call anything that which nature intends it to be, and which belongs to it, rather than that which it is by constraint and contrary to nature. The evidence of the senses further corroborates this. How else would eclipses of the moon show segments shaped as we see them? As it is, the shapes which the moon itself each month shows are of every kind straight, gibbous, and concave-but in eclipses the outline is always curved: and, since it is the interposition of the earth that makes the eclipse, the form of this line will be caused by the form of the earth's surface, which is therefore spherical.

Again, our observations of the stars make it evident, not only that the earth is circular, but also that it is a circle of no great size. For quite a small change of position to south or north causes a manifest alteration of the horizon. There is much change, I mean, in the stars which are overhead, and the stars seen are different, as one moves northward or southward. Indeed there are some stars seen in Egypt and in the neighbourhood of Cyprus which are not seen in the northerly regions; and stars, which in the north are never beyond the range of observation, in those regions rise and set.

All of which goes to show not only that the earth is circular in shape, but also that it is a sphere of no great size: for otherwise the effect of so slight a change of place would not be quickly apparent.
Hence one should not be too sure of the incredibility of the view of those who conceive that there is continuity between the parts about the pillars of Hercules and the parts about India, and that in this way the ocean is one. As further evidence in favour of this they quote the case of elephants, a species occurring in each of these extreme regions, suggesting that the common characteristic of these extremes is explained by their continuity. Also, those mathematicians who try to calculate the size of the earth's circumference arrive at the figure 400,000 stades. This indicates not only that the earth's mass is spherical in shape, but also that as compared with the stars it is not of great size.

In God and reason in the Middle Ages, Edward Grant writes that:

‘All medieval students who attended a university knew this. In fact any educated person in the Middle Ages knew the earth was spherical, or of a round shape. Medieval commentators on Aristotle’s 'On the Heavens' or in the commentaries on a popular thirteenth century work titled ‘Treatise on the Sphere' by John of Sacrobosco, usually included a question in which they enquired ‘whether the whole earth is spherical’. Scholastics answered this question unanimously: The earth is spherical or round. No university trained author ever thought it was flat’

John of Sacrobosco's book, the ‘Treatise on the Sphere' or 'Tractatus de Sphaera' mentioned by Grant, was published in 1230. This popular work discussed the spherical earth and its place in the universe and was required reading by students in all Western European universities for the next four centuries. If the 'poor benighted medievals' had really believed that the earth was flat as was claimed in the 19th century, they must have been ignoring their own textbooks. Perhaps the heavily annotated copy of 'Treatise on the Sphere' shown on the right has been graffitied by scholasitics claiming 'it's not true!' and 'this is heresy!'; but I highly doubt it.

And yet the popular conception of Columbus’s voyage is that he discovered the world is round, in the process refuting the medieval view. The culprit here was Washington Irving, which conjured an imaginary scene in which Columbus pleads his case for a spherical earth in front of Church dignitaries and professors in Salamanca. In Washington’s imagination, Columbus ‘who was a devoutly religious man’ was assailed ‘with quotes for the Bible and the Testament...such are the specimens of the errors and prejudices, the mingled ignorance and erudition and the pedantic bigotry with which Columbus had to contend’

The truth is that when Columbus was planning his voyage, he gathered evidential support from a scholastic treatise entitled ‘The Image (or representation) of the world (ymango mundi)’ which had been written by the theologian and philosopher Pierre d’ Ailly and was one of the most popular printed books in the later fifteenth , sixteenth and early seventeenth centuries. Not only did D’Ailly say from the very outset of the treatise that the earth is a sphere, but he also cited Aristotle and Averroes in reporting that the end of the habitable earth towards the east and the end of the habitable earth towards the west are very close with a small sea in between. D’ Ailly reported the earth’s circumference as 56 2/3 miles multiplied by 360 degrees, as measured by Alfraganus (al-Farghani). Edward Grant reports that, in Columbus’s annotated copy of the book, this circumference measurement has been written in the margin and surrounded by boxes to emphasise the point. This was important for Columbus because it made the world seem much smaller than it actually was, so that sailing from Spain to India would require only a few days to cross the small sea. In fact, by going with the smaller estimate Columbus had underestimated the distance he would have to travel to India, and had the Americas not been in his path he would have run out of provisions.

Not only did Columbus not discover that the earth was round – that had been the scholarly consensus since Aristotle, despite the best efforts of the self educated Cosmas Indicopleustes – he gained the information for his voyage from medieval sources.

As Grant concludes in ‘God and reason’:

Although some progress has been made in rectifying the egregious historical error that a flat earth was commonly assumed in the Middle Ages, the error lives on. Perhaps it is because, as Russell plausibly suggests ‘the idea of the dark middle ages is still fixed in the popular consciousnesses and consequently ‘no caricature is too preposterous to be accepted.

Discuss this post at the Quodlibeta Forum


Roger Pearse said...

I'm currently translating the 10th century Arabic Christian historian Agapius, who repeatedly refers to the world as a sphere.

Anonymous said...

I do not understand this obsession with the flat earth theory. I am writing a book on relics between 300 and 1500 AD. I am overwhelmed with medieval accounts of resurrections ( forty by Thomas Canteloupe ,bishop of Hereford alone) healings, the destruction of pagan shrines by saints, the winning of battles because God intervened on the 'right' side in the nick of time, etc. etc. Believing that the earth was flat seems very tame in comparison with what the medieval mind could be induced to believe!

Bjørn Are said...

The medieval mind in such matters was almost as untame as in our days.

At least that is what I gather from reading all these New Age magazines, not to mention watch movies.

And believing you are on the side of the good, and helped by all and any benevolent spirit, has been the norm for mankind for milennias.

I can't even begin to fathom what historians will say about our age in a thousand years.

Humphrey said...

Just to echo what Bjorn has said. The reason we bring up the 'flat earth' myth is that it continues to be repeated by popular historians, the most recent being the House of Wisdom by Jonathan Lyons. When the myth disappears the obsession will end.

As for credulity, my opinion is that we would do well to be humble. The idea that God, or spirits have intervened in battles was around well into the 20th century. The angles of Mons springs to mind ). By way of illustration, taking a brief survey of my office, 4 believe in the existence of ghosts, 2 believe the trade centre bombings were a fix by the US government, 1 believes the moon landings were faked and several believe in UFOs. These are all highly educated people. The mediaevals mostly were not. Believing in myths and stupid stuff is part and parcel of human nature, even in the 21st century.

Humphrey said...

Whoops, that should be 'angels of Mons'; angles would have been much more mundane.

Anonymous said...

The difference between our age and the medieval one is that we have an elite of scientific minds who have shown how science can bring permanent benefits to humankind. In the medieval era , belief in the miraculous was encouraged both by secular rulers and the church. I have yet to find any record of anyone opposing the idea of the miraculous before Spinoza in the seventeenth century. In the early centuries there were a few Christians e.g. Vigilantius, who did deplore the credulity of their fellow Christians (and was rubbished by Jerome for his pains) but by the sixth century that tradition has been silenced.

James said...

Aren't you just being anacronistic? What possible reason (apart from getting in your good books) did medieval people have for an outright rejection of all miracles. Even today, that seems rather dogmatic.

We know that the scientific elite of the Middle Ages all knew that miracles were contrary to the usual course of nature. So they could happily proceed with their philosophical inquiries by ignoring the slight possibility of miracles.

Also, just because a story is told in a devotional text in no way supposes that everyone believed it to be true. And rosters of miracles gathered to get someone canonised were obviously not all going to make the grade once investigated. You've doubtless already read Bartlett's The Hanged Man which details just how carefully such claims were analysed.

Best wishes


Anonymous said...

Robert Bartlett's The Hanged Man is excellent but the church still accepted the resurrection account there- and once Thomas was accepted by an ecclesiastical court as a saint who could do resurrections, lots more followed. Bartlett says 40- another account says 60! Bartlett's book on the Supernatural is also worth reading - he has an excellent example of how Christian 'rationality' disproved the possibility of the existence of other continents. I increasingly admire the ingenuity of the medieval mind but so long as God's power to intervene so widely was accepted as the norm 'scientific' thinking was bound to be limited which is why it is so hard to find any evidence of medieval thought actually underpinning the seventeenth century so-called scientific revolution - although Gaukroger in his The Emergence of a Scientific Culture (Oxford 2006) has some interesting things to say.

James said...

Hi Charles (I assume),

Actually, I found Gaukroger has very little to say about medieval influences, it is early modern religion that he believes was the essential factor.

But you should also read Funkenstein's Theology and the Scientific Imagination (hard going though), Edward Grant's Foundations of Modern Science in the Middle Ages and, if I can be so immodest, my own God's Philosophers out in August.

Best wishes


Humphrey said...
This comment has been removed by the author.
Humphrey said...

"'scientific' thinking was bound to be limited which is why it is so hard to find any evidence of medieval thought actually underpinning the seventeenth century so-called scientific revolution"

You should try a bit harder. I'll reel off a few examples:

The Baconian tradition gave us a new rhetoric of experiment but if you look at the middle ages you will find plenty of experimental efforts, one thinks of figures like Levi Ben Gerson, Johannes de Muris, Paul of Taranto, Peter Peregrinus of Maricourt and Roger Bacon, who became a propergandist for empirical methodology long before Francis Bacon (see especially scienta experimentalis).

Keplar's theory of the retinal image emerged not by repudiation of the dominant medieval theory of vision, but by accepting and rigorously applying all of its defining claims

Galileo's dynamics and kinetics of motion drew substantially from fourteenth century developments at the university of Oxford and Paris. His idea that projectile motion is the result of an impressed forces is clearly inspired by the 'impetus' of the fourteenth century.

Nicole Oresme devised a predecessor of Cartesian co-ordinates in the fourteenth century.

The pre-occupations of theologians and natural philosophers with the theme of divine omnipotence led to the idea that the behaviour of a contingent world cannot be inferred with certainty from a known set of first principles, an essential view for the development of empirical methodologies.

Humphrey said...

"I increasingly admire the ingenuity of the medieval mind but so long as God's power to intervene so widely was accepted as the norm 'scientific' thinking was bound to be limited"

No medieval natural philosophers believed that God meddled frequently or arbitrarily with the created universe. Rather the perceived consistency of God meant he could be expected to abide by the order established at the point of creation. Thus God's absolute power was limited, for practical purposes, to the point of creation and was no impediment to natural philosophy.

Anonymous said...

Grant's more recent Science and Religion, 400 BC -AD 1550 perhaps provides a better perspective as he is able to give full space to the Greek background and show how the condemnations of the church authorities e.g. 1277, sometimes forced minds into unexpected responses which inadvertently led to scientific developments. Fascinating stuff -but the documented miracles rolled on in their hundreds whatever!

Humphrey said...

It's interesting to see how the condemnations set limits for natural philosophy and gave it a steer in the right direction. One has to see the debates in context though and be careful of using hindsight. The medieval world did lay the foundations for the scientific revolution, which I think was a metaphysical revolution rather than a methodological one. That being the case, I will forgive them for the ridiculous proliferation of miracles.

Bjørn Are said...

Miracles - the deep experience or frequent fantasy that there were exceptions to the rules - were strengthened by the same belief that facilitated a scientific metaphysics.

The belief in a Law Maker behind the universe made it reasonable to believe both in the possibility of Natural Laws and in miracles (and hence in some (or many) miracle stories).

While the first was vindicated by studies during the centuries, the second one was not - or at least not in quite the same way.

However why this should lead one to insist that their metaphysics as such were wrong or silly, is beyond me.

Bruce Williams said...

The Greeks carried gynecological tools in their doctors kits. You didn't see that after the Christians took over until what, the 17th century?

And the flat Earth - The Church in Europe taught that for hundreds of years until the Renaissance.

And the Dark Ages of Europe did not mean the rest of the world fell into Christianity's stupidity.