You sometimes hear that European explorers in the 1400s or so were especially brave as they didn’t even know if, in setting off across the ocean, they might drop off the edge of the world… Was the belief that one could fall off the world ever very widespread, or have people more or less known for millennia that we live on a globe and can exist all over it without falling off if you are not “on the top” ?
My understanding is it was one of those things people had been theorizing for a long time, and most educated people already believed the earth to be round by the 1400s. But of course during that time, education was relatively scarce and there were still plenty of others squawking a lot of misinformation (hmm…) so basically some did, and some didn’t.
Here’s a cite that puts the first round-earth theories around 500 BCE.
You’d have to figure that the most enlightened thinkers of the time were only 99% sure that there was no edge out there, not having proven that fact empirically. Which would make them plenty brave, by my standard.
The contemporary analogy is the atomic scientists who couldn’t be absolutely certain than a nuclear detonation wouldn’t somehow set off all the atoms in the world to blow up in a chain reaction. I remember reading how late (1930s at least) some scientists were striving to show other scientists how this wouldn’t happen, and it seems only logical that there were a few hardcore conservative thinkers who still found this a frightening possibility well into practical development of the first nuclear explosions.
There’s a big difference between being 99% sure that something would end your life and being 100% sure. If you hand me a gun and tell me that there’s one chance in a hundred it’s loaded, I’m absolutely not going to fire it at my head, but if I’ve looked into the chambers and convinced myself that it’s empty, I’ll fire it anywhere I please.
They knew that the world was round. The classic example given is Columbus who bucked the conventional wisdom, not by insisting that the world was round, but by insisting that the earth’s circumference was substantially smaller than most academics believed (The academics of his age were more correct than he was, which is why the West Indies were where he thought Indonesia would be.
Even if they didn’t know that the world was round, the sailors and officers on their ships had probably figured it out after watching the land drop below the horizon on outbound voyages. Also, fishermen from Northern Europe had been fishing the Grand Banks for generations, landing in Nova Scotia occasionally. They had probably at least heard that there was land out there. Columbus, for example, may have gone on a fishing voyage to the Grand Banks (Sorry, but I don’t have time to find links right now.)
They were 100% sure. Since the time of the Greeks it had been known that the earth was round. Our ancestors had eyes and common sense. Don’t forget that the ‘edge of the earth’ would be the horizon, a mere 20 miles distant. Anyone watching a ship slowly sink from sight would have evidence enough of the earth’s curvature.
The way I was taught it (a) agrees with what has been said for coastal cultures, like the Greeks, but (b) there was uncertainty about how far down one could sail without going off the edge. As I understand it, this is why Magellan’s crew underwent a mutiny - for fear of sailing too far down and falling off the edge. (The idea of “gravity” hadn’t caught on quite yet, I guess.)
Under “flat earth” Wikipedia suggests:
The common misconception that people before the age of exploration believed that Earth was flat entered the popular imagination after Washington Irving’s publication of The Life and Voyages of Christopher Columbus in 1828. This belief is even repeated in some widely read textbooks. Previous editions of Thomas Bailey’s The American Pageant stated that “The superstitious sailors [of Columbus’ crew] … grew increasingly mutinous…because they were fearful of sailing over the edge of the world”; however, no such historical account is known.[68] Actually, sailors were probably among the first to know of the curvature of Earth from everyday observations, for example seeing how mountains vanish below the horizon on sailing far from shore.
– always assuming, of course, that Wikipedia can be trusted 
But it sounds plausible that it could have been a later myth based on assumptions that people were ignorant in those days. Would be interesting to know if it is in fact true that there is no documentation from the time to suggest such a fear on anyone’s behalf
Anyway, thanks for the thoughts so far
Possibly attacking the question with a bit too much logic, but…
“If there’s an edge of the ocean, then the water must constantly be falling off it in some gigantic cataract. Is there really enough rain falling on the ocean to keep the high water mark from dropping and dropping until the ocean is nearly all gone?”
Note that roundness and falling off the Earth were not completely distinct issues to the ancients. The Greeks had considered the idea of people living in the antipodes who hung upside down from tree branches. (Although “antipodes” means “feet opposite”, so someone had a clue.) Ergo, some sailors may have thought that if you sailed far enough you might have slipped off the side of a round Earth.
There was no clear cut concept of gravity. Elements sought their own natural level. So the oceans may not have also flowed off due to the “fact” that water just didn’t do that.
I’m not sure how you’d be 100% sure of that.
The only thing I’d be willing tp accept, to settle the OP, would be some ancient documents that were absolutely contemptful of anyone who considered the possibility of being able to sail around the world. The kind of contempt that evolutionary biologists now have for creationist biologists would probably fall short of that absolute sense of haughty superiority that I’m requiring for 100% certainty. So: cite?
I doubt it. Wouldn’t that require the sea surface to slope away more and more as you got further away from the top of the Earth? Sailors, above all, would know that doesn’t happen. The sea is always level.
Columbus did face a mutiny by his crew on October 10, but all his account says is:
“Here the people could stand it no longer, complained of the long voyage; but the Admiral cheered them as best he could, holding out good hope of the advantages they might have…”
Later accounts suggest that Columbus promised to turn back if they did not sight land in two or three days.
As far as I am aware, there was no suggestion that the crew was fearful of sailing off the edge of the world. They were apprehensive about being farther from shore than any other Europeans had ever been before, and worried by the extreme length of the voyage by contemporary standards; but they didn’t see falling off the edge as a possibility.
Magellan was also faced with a mutiny during the winter he spent in Patagonia, but it was for politcal and personal reasons, and had nothing to do with fear of falling off the edge.
I thought it was more a fear of the open sea stemming from the fact that the sophisticated equipment that enabled navigation away from visible land was pretty new.
Prior to the age of exploration, most sailing involved hugging coastlines, always being fairly close to land and frequent port calls. The first time you spend three months with nothing to look at but a huge flat expanse of ocean and no idea when you’ll see land again, I could see being very afraid.
The laws of Physics as we know them weren’t known back then. The small expanse of ocean that sailors generally travelled may not have suggested a global concept of level. God could always make things seem level until … aaaayyh.
Not necessarily. Think of a tray full of water to the brim. There is an edge and you could fall of it (if you were the right size) but it is not emptying. Rain on it would cause it to overflow and create the traditional cataract effect of cartoons, but not empty it.
Educated persons knew the Earth to be round - Erathostenes and some of the other old boys had deduced not just that, but also the size of the earth, with pretty good accuracy.
Ptolemy even listed (not very practical) ways to compute longitude and latitude from observations. In the 15th century, if you bothered to think about it at all, you knew the earth to be round.
Columbus’ challenge to the conventional wisdom of the time was his idea of the size of the Earth - and he was wrong.
The evidence of the horizon doesn’t prove that the world is round, only that it’s convex.
Which atomic scientists were those? All of the ones working on the Manhattan project knew that wasn’t possible, and I can’t imagine that there were very many atomic scientists at the time who weren’t working on the Project.
And no, they couldn’t have been 100% certain that they wouldn’t fall off the Earth, but then, we can’t be 100% certain that we won’t fall off the Earth, either. For all we know, there’s a spot 122.7 miles east by northeast off the coast of the Azores where gravity works backwards for 17 minutes on every third Tuesday. But there’s some level of certainty which is good enough for our daily lives.
It works for Terry Pratchett :).
Also, Balthisar makes a good point.
Spiny Norman: You quoted my post but then discussed a whole other thing. Quoting the wrong person?