What evidence is there that there was a violent backlash against believing in flat earth through the Middle Ages?  This is pure fantasy.

Because there is little recorded about the beliefs of the uneducated we cannot say with certainty what they believed.  It is possible that they believed in a spherical earth.  Uneducated sailors did.  I limit my statement to the educated because that is what there is clear evidence for.

It is absurd to claim as the Catholic position a view that there is no evidence of being taught or believed by Catholics for over a thousand years.

No, its not fantasy.  The arguments Cosmas expounds on show how much pressure he endured for arguing against the pagans in 550 AD.  Writings during the Galileo Affair give a clue as to the pressure brought to bear on the Church, let alone individuals.  I've read many docuмents showing how scientists, astronomers, sailors, engineers, etc were made to cooperate. Samuel Rowbotham and others go into detail about this specifically. The billions NASA spends indoctrinating the masses show they are not playing games. Friends I know have struggled with incredible pressures from schools. I've experienced most all of this myself.  As far as the world's concerned, you CANNOT believe earth is flat, or you're really really stupid.  And you will be opposed.     
Yes, over a thousand years. The truth is a teaching as old as Scripture.

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Fascinating how there has been a 4-page barrage (66 posts) of flat-earther posts trying to bury the thread.
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Flat-earthers must be terrified of the truth.
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The earth's magnetic field is constantly changing. In the past, variation from year to year has been not so great so as to make estimates of location unreliable from place to place worldwide, and such practices as land surveying and navigation at sea have been able to use updated maps for currently reliable data. In recent years, however, the magnetic poles (called dip poles) of the earth have been moving more quickly such that services and trades that rely on currently updated locations of the dip poles have had to obtain more frequent assessment and updates.
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Observed north dip poles during 1831 - 2007 are yellow squares.

Modeled pole locations from 1590 to 2020 are circles progressing from blue to yellow.

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[Obviously, the locations for 2020, 2019, 2018 and 2017 are estimates. This present data is current as of 2015.]

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Magnetic poles are defined in different ways. They are commonly understood as positions on the Earth's surface where the geomagnetic field is vertical (i.e., perpendicular) to the ellipsoid. These north and south positions, called dip poles, do not need to be (and are not currently) antipodal. In principle the dip poles can be found by conducting a magnetic survey to determine where the field is vertical. Other definitions of geomagnetic poles depend on the way the poles are computed from a geomagnetic model. In practice the geomagnetic field is vertical on oval-shaped loci traced on a daily basis, with considerable variation from one day to the next.

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It has been long understood that dip poles migrate over time. In 1831, James Clark Ross located the north dip pole position in northern Canada. Natural Resources Canada (NRCan) tracked the North Magnetic Pole, which is slowly drifting across the Canadian Arctic, by periodically carrying out magnetic surveys to reestablish the Pole's location from 1948 to 1994. An international collaboration, led by a French fundraising association, Poly-Arctique, and involving NRCan, Institut de Physique du Globe de Paris and Bureau de Recherche Geologique et Miniere, added two locations of the North Magnetic Pole in 2001 and 2007. The most recent survey determined that the Pole is moving approximately north-northwest at 55 km per year.



Modeled pole locations for magnetic north from 1831 to 2020 [1831.000 - 2020.000 -- these are not observed north pole locations]:
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222.596 85.370 2011.000 217.521 85.676 2012.000 211.982 85.933 2013.000 206.059 86.138 2014.000 199.975 86.289 2015.000
193.710 86.395 2016.000 187.413 86.455 2017.000 181.245 86.471 2018.000 175.346 86.448 2019.000 169.818 86.391 2020.000
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[The years' data for 2015 and 2017 are in bold - degrees longitude west, degrees latitude north, year.]
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The cause of the earth's magnetic field is not actually known, but there are theories proposed that would explain it. It is thought that some large quantity of ferrous material in the earth's core is moving to produce this field, but how much iron, where exactly it's located and how fast it's moving are all unknowns and up for speculation. One thing scientists can agree on is that wherever this iron is precisely, it exists at a temperature of over 1,000 degrees Fahrenheit, or perhaps even 2,000, which would mean it would be molten at atmospheric pressure, however, since it is expected to have an ambient pressure of hundreds of atmospheres, the liquidity/solidity or whatever state it is in cannot be certain. In any event, since the magnetic poles of the earth are observed to in fact be moving, we can reasonably presume that the ferrous or iron mass deep within the earth must not only be moving so as to generate this field but must be moving in a variable manner, that is, moving differently today than it has moved in previous centuries.
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Since it is essentially unknown what forces are acting on the iron inside the earth, we cannot know for sure what kinds of changes the magnetic field will undergo in the future. We can presume to expect it to move in a somewhat predictable manner, but as you can see from the image above, in the years 1732 (George Washington's birthday and the square root of 3), 1859, 1890 and 1900 the north dip pole changed direction of drift quite abruptly and without apparent or observable cause as far as we know (the birth of Washington or the square root of 3 can't explain a pole shift), therefore a similar change could likewise occur in our present age and we have no way of predicting it or even of anticipating when or whether it will occur.
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The point is, the magnetic north pole has been moving for centuries, and where it was and where it moved to has been docuмented as shown above.
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Something is going on inside the earth for this to take place. What exactly that is has yet to be determined but it must be some kind of great movement of physical matter below the surface of the earth.
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We know there is movement of the oceans' waters, but there is no correspondence between the location of the magnetic north pole and the movement of water in the oceans.
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Something we cannot see, underground, is moving which produces a change in the location of the magnetic north pole.
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With the globe earth model, considering volcanic action and earthquakes, it is quite simple to expect that something deep inside the planet Earth moving could cause the magnetic north pole to change positions as it has been recorded (which see).
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But with the "flat" earth model, what could possibly explain the movement of the magnetic north pole?
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It is clear that flat-earthism is all founded on superstition, feelings and fantasy, which is unscientific and more.
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She studiously ignored the question: she doesn't want to be shown saying God is really really really stupid for saying the sky is strong and hard.

STATUS OF THE THEOLOGICAL DEBATE --

JayneK -- these passages in Scripture CANNOT be interpreted literally

Flat Earthers -- these passages in Scripture MUST be interpreted literally

Ladislaus -- it's possible that these passages should be understood literally, but it's also possible that they can be read metaphorically.  Neither one is strictly required by Catholic teaching.

Ladislaus, you really like your "I am not on anybody's side" schtick.  You remind me of the dwarves in the C.S. Lewis story, The Last Battle.  There is a scene in which a major battle is taking place between the forces of good and evil and the dwarves stand off to the side randomly shooting arrows at both sides.

STATUS OF THE THEOLOGICAL DEBATE 2

JayneK -- Church Fathers who interpreted Scripture as referring to flat earth were wrong

Flat Earthers -- there's nearly unanimous consensus of Church Fathers that Scripture referred to flat earth, and so they must (infallibly) be right and their interpretation regarded as being of faith

Ladislaus -- MOST, but not all, Church Fathers did read Scripture as referring to flat earth, but there's no indication that this interpretation reflected a teaching handed down from the Apostles as part of the Deposit rather than their own thinking (as per Leo XIII's PD) ... so there's no clear evidence of DOGMATIC consensus ... and yet it's also quite possible that they were right (and that cannot be ruled out)

From PD
We say, are of supreme authority, whenever they all interpret in one and the same manner any text of the Bible, as pertaining to the doctrine of faith or morals; for their unanimity clearly evinces that such interpretation has come down from the Apostles as a matter of Catholic faith. The opinion of the Fathers is also of very great weight when they treat of these matters in their capacity of doctors, unofficially; not only because they excel in their knowledge of revealed doctrine and in their acquaintance with many things which are useful in understanding the apostolic Books, but because they are men of eminent sanctity and of ardent zeal for the truth, on whom God has bestowed a more ample measure of His light. Wherefore the expositor should make it his duty to follow their footsteps with all reverence, and to use their labors with intelligent appreciation.

 But he must not on that account consider that it is forbidden, when just cause exists, to push inquiry and exposition beyond what the Fathers have done; provided he carefully observes the rule so wisely laid down by St. Augustine — not to depart from the literal and obvious sense...



Now, it can be said, strictly speaking, the opinions of the Fathers were not unanimous in this flat geocentric matter, but most of them who opined describe a flat motionless earth. The last bold line (above) must also be considered--the literal sense of Scripture. With these two things in mind, we can say the majority of Fathers were of this opinion, and also, that we ought not depart from the literal and obvious sense of Scripture, concluding it is far wiser to accept what has been given us, knowing that we are utterly devoid of phenomenological or metaphorical interpretations describing the globe. As the evidence mounts for flat earth and against the globe, it seems flat earth has gained a hard won dais, deserving our attention, even an ascent of faith. After all, faith is not about seeing or understanding, but believing even though we don't fully understand; not because we are wise about interpreting Scripture, but because God has provided precious pearls in the form of clues so that we will ask, knock and seek. Even if all of this isn't enough for globalists, they can no longer deny a powerful argument exists from Tradition for the flat earth, nor reasonably entertain the perception that flat earth is automatically false, or stupid.      

So what?  As the article you posted indicates, nobody knows what that "something" is, and so it cannot be demonstrated that this "something" requires a globe earth to happen.

FAIL

When I see really bad arguments being made as if they prove something, it's a clear sign that the person making them has already pre-determined the conclusion or the outcome and is backfilling "arguments" to make it seem plausible.  I see this on both sides here in this debate, and I'm not interested in any of it.  I'm looking for real arguments that will lead me to the truth.

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There are two models in question
-- the spherical earth with an enormous spherical core of at least partially molten (hot) material, most likely rich in heavy elements such as iron, which when moving (as electric motors demonstrate) involves magnetic fields;
-- and a "flat" earth with nothing at all underground in motion and consequently nothing to explain a moving magnetic north pole.
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"So what?" you say. All righty then.
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I could break it down further for you but I doubt you would pay attention. And flat-earthers would resort to Bible quotes, or the "Church Fathers" who obviously knew nothing about magnetic fields because it was not a topic of discussion yet for hundreds of years yet to come.
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News flash:  The Bible has no mention of electric motors, magnetism or magnetic fields.
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