Philosophy 167: Class 2 - Part 3 - Islamic Astronomy: Ibn al-Shatir, and Innovative Astronomical Research in the Islamic World.

Smith, George E. (George Edwin), 1938-


  • Synopsis: Tells how Edward S. Kennedy acquired a manuscript that turns out to be a comprehensive alternative to Ptolemaic astronomy by Ibn al-Shatir; emphasizes that Copernicus was indebted to Islamic science.

    Opening line: "In 1957, Edward S Kennedy, a professor at the American university in Beirut, Lebanon."

    Duration: 12:45 minutes.

    Segment: Class 2, Part 3.
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In 1957, Edward S Kennedy, a professor at the American university in Beirut, Lebanon. I should pause a minute, because I doubt anybody quite realizes this. The same university that Dan and his father was a teacher at, and Dan didn't do Edward S Kennedy, because he lived in Beirut at the time with his father.
His father died young from a heart attack. That's an aside, but it's a major university. American University in Beirut at the time. It was an important university in all respects. Edward Kennedy was at Oxford. And asked for a particular manuscript out of the Bodleian library, got a manuscript that was different from the one he asked, he's studying the near East, so he's getting a manuscript in Arabic.
And he started looking at the one they delivered to him in Arabic, and he realized almost immediately I don't know the existence of this manuscript and I don't think anybody else has ever commented on it. So he looked further and realized it had a complete comprehensive alternative to Ptolemaic astronomy.
Sun, moon, all the planets. And, the best he could tell eliminated all violations of circular motion. Fixed the problems with the moon. And had the earth at all times in the center just as Aristotle wanted. So now he goes out with this new manuscript. We still don't have it.
Publicly goes out and enlists some friends of his who know more astronomy than he does, and they discover, low and behold, that almost every innovation in astronomy attributed to Copernicus, except heliocentricism, was already present in this manuscript. To such an extent. I'll make the case later. It's beyond all possibility that this is coincidence.
Okay somehow, the name is Ibinalsia Tere. I butchered the name. You want to say it properly for me?
Ibinalsia Tere
Thank you. I don't have a hope in pronouncing Arabic, believe me. I've tried. I'm just very slow. If I can't do French, I can't do Arabic.
How's that? Somehow or other, Ibinalsia Tere's work managed to get into northern Italy when Copernicus was in university there. We'll talk about that later. And people called his attention to this alternative. And he didn't know the name. There's no reason to think he could read Arabic, no reason to think he saw the actual manuscript, but he got enough information to sew almost all the problems other than heliocentrism.
We'll get to that later now. What then happened historiographically was people realized the late medieval Islamic period was not a period of simply carrying forward classic Ptolemaic astronomy. It was a period of, and this is a summary from George Saliba's book. Pass this book around, this is a 2007 book arguing for a new historiography of late Islamic.
What it says at the top, in astronomy the Islamic reactions to Ptolemy ranged from simple corrections of what was thought to be a mistake in the text. Of the Almagest. To correcting the basic parameters by fresh observations. Those aren't The Elements, by the way. As in the case of redetermining the better values of procession and inclination of the ecliptic among others.
To critiquing the methods of observations, this was done etc. I'm gonna stop that paragraph, you can go on in a moment. The thing about procession is important because that happened early on. Two important Islamic innovations occurred early enough to have reached Spain. One is that Ptolemy's rate for the procession of the equinox was way too low.
It was moving faster than that. The second was that the tropical year is not what you ought to be using. You ought to be using the sidereal year. That's a publication that's one of the few of these Arabic publications that's now been translated. You can see it referenced in the select sources.
Norgabauer translated it. That led by the way to the Alfonsine tables incorporating a very funny way of handling procession of the equinox. And I'll tell you a lot about how people thought. So by the time of the Alfonsine Tables processions moving faster than Ptolemy said it was. Of course they couldn't be wrong, so therefore the procession of the equinox must be going at a variable rate.
So they introduced the variable rate called trepidation and that just moves right forward then. Everybody starts using it under the presumption that at one time it was one degree per century. Now it's around seven-tenths of a degree per century. But it's gonna cycle back at some point, and everybody's trying to figure out when it's gonna cycle back.
But that's a feature of this, but the main thing I wanna get to is the part I've blocked off at the end. It was in this environment. It's an environment of, it starts with a phrase. I'm not going to try to pronounce the Arabic word, a whole bunch of publications, manuscripts, publication's the wrong word, manuscripts under the word which means doubts.
The whole manuscript's expressing doubts about Ptolemaic astronomy and listing them and arguing. That gave way about the time the Moors invaded Spain and the other route took hold that gave way to a group of astronomers, primarily in a school centered in Iran, but stretching all the way to Damascus, which is where Ibinalsia Tere was, gave rise to people starting to introduce new mathematical techniques.
To replace Ptolemy, trying to achieve the same accuracy as Ptolemy, but getting rid of violations of circular motion, uniform circular motion. Getting rid of the Sun being off-orbit, et cetera. So that's what's said here. It was this environment that motivated the research of the new Islamic astronomy. It's main mission was enunciated later by Erde.
I'm not gonna do the rest all 66 of Damascus one of the most distinguished astronomers of that tradition was to create an astronomy that did not suffer from the cosmological short comings of tallamake astronomy. That could account for the observations just as well as Ptolemy astronomy could do, if not better.
And it did not limit itself to criticizing Ptolemy only, despite all the benefits that wandered out from detail critique of Ptolemy's mistakes. This urgent need for a higher form of Scientific Astronomy was almost felt by all serious astronomers whose work we have come to know only recently and we formed a continuous tradition inaugurated toward the beginnings of the ninth century and continued well into the 60s as far as we can know now.
Now the problem here is, the discovery of that one manuscript in 1957 has made people working in this area aware that there's just got to be a whole lot else out there. Ibinalsia Tere didn't suddenly do this in 1350. Slowly but surely the manuscripts are surfacing. None of them so far have been translated into English.
None are available. What's the oddity here? Printing press 1450 in Europe. Printing press in the Arabic world at the end of the 19th century. I've been told because the Ottomans opposed it but I don't know if that's true. I've also been told that Arabic is not an easy language to do printing in.
Because what is cursive, basically, and that makes it much more complicated. Regardless, what we've got out there that we're in the process of discovering now, or people are discovering, what we've got out there is probably just a lot more Islamic advances in astronomy that made their way into Europe.
By roots we can't trace at the moment. We know pretty well what had to happen. There was very active trade between the Near East and Venice. And there were lots of people. I know one person who's studying a group of Jewish merchants. Who were fluent in Arabic and fluent in Latin, as well as fluent in Hebrew.
And who brought other things, medical things, into Venice. And the presumption is, people like this coming as merchants from the Near East brought a lot of learning into Europe that we at the present moment can't trace, but we can see its consequences. Now, two last remarks about this.
One of the, I'm the one who italicized whose work we've come to know only recently. This is happening now. And, therefore, what we're going to think 50 years from now about the role of Islamic astronomy and the development of European astronomy. It may be very different than the position we're in now.
The second point is, I make it a practice. I'll explain this when I make it a personal practice to try never to depend on the secondary source for any point about history. Now it's not because I don't trust historians. In fact, and I hope you learn this in this course, it doesn't take long to learn to which historians are careful historians and which historians are either engaged in a form of advocacy, like a lawyer.
They decide beforehand what the truth is gonna be and they look evidence for it, or worse than that, which historians are frustrated novelists just making up a story and the important thing is the story be a lot of fun. You're very quick to pick these up once you start reading history.
You can tell the people, and the way I like to say it, make the point very quickly. I've said that I'm not a historian, but I've said my principle discovery in doing historical research through historians, and they all agree with this, you start with a particular picture of what you're researching.
If it doesn't come apart and you don't have to start all over again, you should be very suspicious you haven't dug deep enough yet. Okay, and it's a good rule of thumb. It's a rule of thumb I follow very carefully. But the problem in my not trusting secondary sources without consulting primary sources, it's not bad historians, it's that they may be asking a slightly different question from me.
What any historian puts down on page in the secondary source is somewhere, it's my favorite number on this, around 5% of what they actually know. Most historians say 5% is pretty high. But, I think 5% Captures me, which means I probably am not a good enough historian yet.
So if I'm asking a slightly different question from what they're asking and I'm relying on them for what's in the primary source, I may be missing the boat spectacularly. So I have a rule. Always at least consult a reliable English translation, and where possible, consult the original. It's frustrating to me there is no available Ptolemy in Greek, at the present moment.
In print. Very frustrating, but here I'm totally reliant on secondary sources. I don't read Arabic, none of it's been translated. None of it has ever appeared in book form in Europe in any language, including Arabic. It's all still a manuscript. So as a consequence, all I can do is report here and go on, but you should you should view what little I have to say about it.
Ibinalsia Tere in relation to Copernicus as a case that's still unfolding and therefore you should not trust it a good deal.