Weren’t they, at the time of Columbus, able to measure angles of stars above the horizon accurately enough to get the circumference of the Earth? Measure the maximal angle of a star (e.g. Polaris) above the horizon at two locations, one due north of the other. This could be done anywhere, and not rely on a well-placed… well.
It was Eratosthenes who used the wells in Syrene and Alexandria, to get the already-mentioned measurement of the Earth.
By about 300 A.D., astronomers already knew not only the size of the Earth reasonably well, but they knew the size of the Moon and the distance to it fairly well. They tried to estimate the size of the Sun and its distance, but the measuring and observing equipment just wasn’t good enough at that time. It may be that some of them got the size and distance of the Sun reasonably close, but the general estimate for those numbers was too small by about a factor of 20.
Columbus thought the world was much smaller. I read that he estimated that he would sight land (the mainland of Asia), about 800 (Spanish) miles west of the Azores. So he prepared for a long voyage, but not impossibly long. By the mid-1500’s the Spanish were making regular voyages from the west coast of Mexico to Manila, in the Philippines…so a a trans-Pacific voyage was well withing their capabilities
I find it strange so many are insulting Columbus here. It’s pretty easy to level criticism against Columbus on moral grounds (even by the standards of his own time) and to criticize his ability to interpret the situation as he learned more and more about the lands he had discovered. But anyone who has ever been on a boat in the Atlantic Ocean should respect his accomplishments. Even with GPS and modern engineering many people every year still die on Atlantic vessels, it’s a violent ocean with frequent major storms. No one knew how big the Ocean crossing was and Columbus sailed into it anyway, in small cramped Spanish caravels. He very well could have died of starvation attempting what he did, or been killed by a storm or just plain gotten lost and never found his way home. This wasn’t like booking passage on the QE2 and having a leisurely trip across the Atlantic.
As for his belief in a smaller Earth, that is not really comparable to members of the “Flat Earth Society” today, as some seem to suggest. There were a range of opinions on the exact size of the Earth, and by and large with less collaboration between learned thinkers in that era it would have been harder to obtain a consensus on any single viewpoint. Columbus wasn’t a crackpot who just adopted random beliefs out of nowhere, his opinion on the size of the Earth was based on estimates by learned scholars who were simply wrong–and also in part driven by unit conversion mistakes between different units of measure communicated through translated texts over spans of many years. That is actually a pretty understandable mistake, and while he was dead wrong Columbus was basing his opinion on the collected beliefs of pretty smart men who had written down their thoughts.
The short response to this is that there is a difference between Columbus the sailor, Columbus the explorer, and Columbus the man. The man was monomaniacal, egomaniacal, cruel, power-hungry, and a fame whore. Those qualities both helped his exploring and hurt it badly. Over his career, the negatives outweigh the positives.
His belief in a smaller earth is a classic case of cherrypicking facts to prove what you want to believe. It’s similar to climate denial today. You can find a sufficiency of independent facts to make that case, but better informed people have already convincingly demolished the theory as a whole. Spain needed a publicity victory against Portugal, though (Columbus was a minor footnote to internal politics), and despite popular belief, Columbus had already picked up a great deal of financing from other sources, making it a cheap deal. If he didn’t come back, they lost little; if he did they won big.
His subsequent behavior convinces me he was a crackpot. That diminishes the bravery involved in sailing those boats across the Atlantic not a whit, but the two are separate issues.
There’s really nothing comparable in Columbus Age to say, Climate change denial. The concept of scientific consensus was far different in 15th century Europe. I view a crackpot as someone who pushes stuff like vitamin supplements to cure all ails or home remedies for myopia or who believes in creationism over evolution or etc. Columbus was working within theories promulgated by accepted learned scholars. If he believed the Earth was a cube or a disc instead of a sphere, or such then maybe you could call him a crackpot. But honestly this was an extremely ignorant time, it feels a bit modernist to call someone who was probably in the top 1% of the educated and knowledgeable men of his day a crackpot. Mind even the smartest men of his era believed in things like alchemy, humors, and various other absolutely incorrect things. Not to mention even where they got things about astronomy for example “mostly right” they often were still significantly wrong.
There is just a world of difference between our time, when scientists work using the scientific method (they did not in the 15th century) and work internationally and collaboratively and that information is disseminated down to understandable levels to basically anyone willing to read it and the time of Columbus. In the time of Columbus if you were born in the wrong place and were a great thinker, you may never in your life have had a chance to read a seminal text in your field, because it wasn’t available anywhere within hundreds of miles. You may not even have known it existed if you were a Christian and the guy who wrote it was a Muslim, and you certainly wouldn’t know if it was from any further away than the near East.
I think given Columbus knowledge, he should have known at least some of the land masses he discovered were large and not small islands in the Indies–he appears to have disregarded that stuff because it undermined his belief that he had discovered Islands in the seas south/southeast of his desired destination. He also frequently exaggerated or lied about his exploits to receive continuing support, and was personally involved in immoral dealings. But I don’t really see much support for making fun of him as some loon or idiot. I think few people correctly understand how difficult it is to make it across the Atlantic Ocean in 1492, or understand how poor information was spread and knowledge shared in that time.
Additionally, based on the best knowledge available to him there is no way Columbus could have known–even if he had accepted he’d ran into a large land mass, that he’d ran into one the size or scope of the Americas, or that it wasn’t just a really big island and the real Indies weren’t that far away still. Yes, if he had accepted the more correct theory of the size of the Earth he’d have known better, but that was not at all settled science. Not even comparable to say, climate change, which is based on consensus of thousands of scientists working in international studies that share mountains of information. Learned men in the days of Columbus would do rudimentary studies, read old texts, and correspond with others who they happened to get to know. But there was no central exchange of ideas, and important knowledge could easily be miscommunicated or completely unknown to large numbers of other learned men.
It’s always tricky to try to ascertain what the public, even the educated public, knew at any given time. Even so, I disagree with you over the state of knowledge in the 15th century. This was 50 years after the printing press. Books and maps were furiously being printed and disseminated. Scholars spent much of their time corresponding with one another, and taking trips to visit with other scholars, and had even before the printing press. I think knowledge was far more homogenous than you say.
The fact that Columbus could get no support for his vision - plan is probably saying too much - from a variety of potential sponsors indicates to me that doubts about his understanding of the world were widespread. If none of the potential funders - who didn’t make the decision themselves, but turned to their learned scholars, sailors, map makers, and other experts - didn’t see the trip as feasible, then it’s reasonable to assume that the experts knew this wouldn’t work. From my reading, that was in fact the case. Columbus, through persistence and luck, stumbled into a situation that - after many years of trying - allowed him to go forward. But that was as much for propaganda as for belief.
Note that when I call Columbus in the top 1% of learned men of his time, this was a time when 90% or so of the human population were engaged in the business of farming. The rest, once you filter out the sailors, soldiers, small parish priests and etc leaves you with a very small group of people who actually read works of knowledge. Among those Columbus was no great thinker or anything, but anyone who was read and actually at least knew about the theories that Columbus knew about has to reckon as one of the more educated men of his time. Sure, the guys like da Vinci or Kepler or Copernicus are the “0.1%” the men actually writing some of the great works or doing the scientific experiments, but the audience of individuals who actually read their works but weren’t also proto-scientists themselves was very small. Basically people of education and enough means to spend time doing that who actually bothered to do so, or certain very interested monks. (While many monks and priests were well read in the sciences, even amongst them most did not spend much time reading up on different theories about the size of the world.)
All long distance sea travel of the time was dangerous, and to “parts unknown by routes unknown” was akin to me trying to raise money for a private moon mission today, whether it relied on an unpopular theory about the size of the world or whatever. This is actually why you had the emergence of insurance schemes and joint-stock companies, because eventually that was what it took to actually get enough capital raised for this kind of thing to become consistent. The Spanish royals also sponsored some expeditions as well, obviously. The group of people who actually were in a position to fund Columbus (and some of them did) most likely weren’t that scientifically literate. There wasn’t a huge overlap between moneyed types (bankers and whatnot) and scientists in the era, the people (like Columbus) who were not scientific types themselves who were informed at all on the various theories was small enough that I doubt that was really the major reason Columbus had trouble getting backers. I suspect it was a simple risk analysis for any seafaring voyage traveling outside established trade routes, compounded with actually crossing a large body of water that no one in history (known to the principals anyway) had ever successfully crossed.
As I said earlier, this is wrong. What the funders did was call in groups of experts. We even know their names. King John II of Portugal used the cosmographer Diego Ortiz, Bishop of Ceuta, and two Jewish geographers, Vizinho and Rodrigo. They turned him down precisely because they thought his geography was wrong. It was more than a “simple risk analysis.” His proposal contradicted facts that all the experts agreed upon.
He then turned to Isabella and presented his case in 1486. A commission of experts was assembled by Fray Hernando de Talavera. Quoting Zvi Dor-Ner in Columbus and the age of discovery (p94):
That was in 1487 or 1488.
Columbus may also - little is certain - have gone to the Genoese government in 1490 or 1491 and Bartholomew Columbus went to King Henry VIII and King Charles VIII in those years. All were turndowns. They would have gone to their experts and gotten the same advice. He was wrong about the distances. Everybody read the same sources and had the same basic information. Only Columbus fudged the facts to make his case.
After Granada fell, Spain was complete and in a far better position to grant requests. The experts hadn’t changed their minds. But Luis de Santangel, King Ferdinand’s Keeper of the Privy Purse, not only advocated for Columbus but offered to pay expenses himself if needed. Since most of the money would be returned if he found anything, the risk was lower than allowing somebody else to back him and reap any rewards.
People did try to keep information secret. It seldom worked. There were experts and the royals usually relied upon them. They mostly all knew the same things and read the same sources. Columbus either knew less than they did or ignored clear reality. That’s an excellent analogy to climate deniers.
Nitpick, but it was Henry VII.
Sorry. Typo in the original that I just copied.
From Wikipedia…
The Europeans were just learning to sail significant distances, even when hugging the land. (Of course, in the days of sailing ships at the mercy of winds and storms, it was not a simple matter of motoring down the coast).
Considering that the Portuguese had just managed to get to the bottom of Africa a few years before, setting out to the unknown on a guestimate (right or wrong) was a bold move.
As for Columbus’ personality, if your sole claim to fame (in your own eyes) was finding a shortcut to the fabled riches to the land of spice and silk, no surprise you don’t want to admit it’s just “useless” wilderness much like the coast of Africa. Just give me a few more ships and supplies and I’ll go the extra few leagues to get to Cathay, the real source of riches.
You seem to have read a lot more about Columbus than I, but as I understood it Columbus sought private backers in Italy for his ventures as well. It is them I would not have expected to be able to analyze the theoretical geographical claims he was making, but instead rejected it based on a standard CBA.
What you’re saying does not really refute my point though, pointing to two royal courts and advisers there and what they thought does not prove a scientific consensus. There was no formal peer review process in the days of Columbus, and the “experts” who analyzed Columbus claim for the monarchs were probably wrong about a mountain of basic scientific facts so the idea that they necessarily should be afforded special credibility is false. I do not know anything about the men you mention, but I know that in general at this point in European history most learned men basically regurgitated whatever they knew from Greek texts along with some of the more recent middle age writers on certain issues (especially theology.) For that reason it is unlikely any of them had direct knowledge (through experimental verification) of the size of the Earth, and I suspect they simply nodded their head at Erastothenes’ number without doing any verification by experimentation of their own.
Columbus was basing his numbers off of reading the estimates of Marinus of Tyre, also a Greek thinker just like Erastothenes. Lacking a series of scientific experiments independently confirming the work of either man, there is no real scientific consensus. In fact most men of “science” still worked on the belief that “logical deduction” was a valid way to arrive at scientific proof instead of hard experimentation.
We all know that Columbus was wrong, but he wasn’t going against the “established scientific community” because there wasn’t one. As someone who wasn’t part of that community, and before an age when science was commonly distilled down to the less scientific minded he relied on (misinformed) readings of his own and influences from several Italian scientists he knew personally who supported the smaller Earth estimates.
I don’t doubt that Columbus knew less than someone employed as an adviser at a royal court, but I also don’t think those guys actually did any scientific testing of their own–aside from a few special cases, which means they were not experts. They were just well read people who by luck, happened to agree with the theories of the Greek thinker who was closer to being correct on the size of the Earth than did Columbus.
You can’t have scientific consensus without real scientists even existing.
I am unknowledgable about Columbus as a person. This is irrelevant to our discussion anyway I think.
We seem to have reached a consensus that he was an excellent sailor; possibly the best European sailor at that time.
What I am perplexed about is why in the world you are leading the charge to call his exploration skills into question? I would turn the tables about “cherrypicking” and say that using our 500+ year advantage of knowledge to critique his judgement about the feasibility of a westward route to the Indies is the real “cherrypicking.”
If you are not yet knowledgable about Toscanelli and his calculations, then please read up about them and see if you can hold on to the black and white judgements you have made so far. As many here have pointed out, it’s not like Columbus got these calculations from some guy shouting from a street corner.
Since we’re using analogies, the proper one to use would be if we had embarked on some (seemingly successful!) endeavor based on Hawking’s belief that Black Holes destroy information. Can you imagine how hard it would be for the leader of that endeavor to change his mind about the rightness of the whole thing, even though we now know that Hawking was wrong? With all that money and prestige riding on it? This stubbornness is unpleasant but very human and very understandable.