Astrology, Astronomy, and the Scientific Revolution

One of the large-scale questions in academic discussions of the Scientfic Revolution concerns the relationship of the developments we today consider scientific to traditions we today consider pseudo-scientific or mystical, e.g. alchemy, astrology, and magic. People who make pronouncements like "There was no such thing as the Scientific Revolution" often justify such a claim by identifying and stressing continuities between mystical/ magical traditions and various new ideas that we now deem 'scientific.'

It is undeniable that significant continuities and similarities exist between pre-revolutionary views of nature and later ones. But I have often had the gut feeling that people sometimes overstate the case. Here is one example, from a brilliant historian of science, Allen Debus:
Some of the scholars, whose work contributed to our modern scientific age, found magic, alchemy, and astrology no less stimulating than the new interests in mathematical abstraction, observation, and experiment. Today we find it easy -- and necessary -- to separate "science" from occult interests, but many could not. (Man and Nature in the Renaissance)
This seemed overblown to me, because from Ptolemy up through Renaissance astrologer-astronomers such as Girolamo Cardano, the distinction between astrology and astronomy is explicitly drawn, and the historical figure often argues for the location of the boundary. So Debus's claim that students of nature during the Scientific Revolution 'could not separate science from occult interests' struck me as demonstrably false -- they could, and they did (at least in the case where the science is astronomy and the occult field is astrology).

But, as I have been working on my Magic, Medicine, and Science class (discussed last post), I've started thinking that there is something very right about Debus's idea, even if I would not couch the matter exactly as he does. What struck me is that, in the Ptolemy-Cardano scheme, astrology is classified as part of physics (in the Aristotelian sense, i.e. the study of nature), for it studies the physical influences of the sun, moon, planets and stars upon the Earth and its inhabitants. (Some astrologers thought the celestial bodies also had non-physical influences on us and our environs.) Astronomy, as mentioned in my last post, was classified as part of mathematics. Ptolemy, for one, states very clearly in Tetrabiblos that astrology studies physical, material causes associated with celestial bodies, whereas astronomy does not. And Cardano writes that astrology, unlike astronomy, studies "how lower things are linked to the higher ones."

So what is right about the Debus quotation? From the point of view of the Ptolemy-to-Cardano distinction between astronomy and astrology, the people working in the 17th C on a new physics of the celestial realm were apparently doing astrology, not astronomy. When Kepler is attempting to discover the physical cause of the planetary orbits, under the older taxonomy, that can't be astronomy, since astronomy does not deal with physical, material affairs. Thus what Kepler is doing (since it's still about the celestial realm) would naturally be classified as astrology. (And perhaps, though this is wild and irresponsible speculation, that partially explains why Kepler's theory, which appeals to entities like the Sun's 'motive soul,' has elements strongly reminiscient of earlier astrology.)

One possible problem with this idea: is there perhaps, in the Ptolemy-to-Cardano classification scheme, a separate heading for works like Aristotle's De Caelo, which does not appear to be straightforwardly astrological? That is, just because the old taxonomy won't count Kepler as astronomy, that doesn't imply that a celestial physics must be astrology: there could be some third category under which De Caelo and Kepler fall. Gentle reader, do you have any information to guide me here?



At 13/10/05, Blogger Kenny said...

Is it clear that contemporary figures always have such an easy time drawing the boundaries? Most scientists don't bother with such things, but then again, most physicists don't bother with chemistry, biology, meteorology, etc. either, and vice versa. And paralleling the few actually interdisciplinary people there are, there's also the intelligent design people, the "parapsychologists", and the AIDS dissidents (and I think a few of each actually do study biology and not just some other science). Not to mention the difficulty of drawing a line between proper evolutionary explanations and the just-so stories some people like to tell.

It isn't obvious to me that scientists today have any easier a time telling science apart from pseudo-science. It might just be that scientists increasingly cut themselves off from everything outside their specific discipline, science or pseudoscience. Though I suppose it is easier to tell the scientists apart from the non-scientists, even if their subjects aren't so clearly separated.

At 14/10/05, Blogger GF-A said...

This comment is just a note to myself: I just finished looking through all of Copernicus's preface to De Revolutionibus (the text is online in english and latin here), and I found a couple of interesting things relevant to this post.

First, he never calls what he is doing "astronomy," but rather always "mathematics." (Though Osiander calls it 'astronomy.') Where the usual translation has Copernicus saying "Astronomy is written for astronomers," the Latin actually reads Mathemata mathematicis scribuntur. That is not a criticism of the translation -- for, as I keep saying, astronomy was a branch of mathematics back then. But that translation could be a bit misleading for a reader who does not know that.

Second, Copernicus writes the following in his introduction to Book I, after saying that the heavens are beautiful and perfect:
"If then the value of the arts is judged by the subject matter which they treat, that art will be by far the foremost which is labeled astronomy by some, astrology by others, but by many of the ancients, the consummation of mathematics."
[Note: in the online Latin text I linked to above, I couldn't find this page, so I don't know what is being translated as 'astronomy' and 'astrology' above.]

At 16/11/05, Blogger PhillyTheo said...

Try to not split hairs as you do in your article. All the astronomers of ancient times and those of the Renassiance were Classic Astrologers. Period.

Know your history. Astrology was the attempt to predict the mathematics (astronomy) of the constellations, stars and planets.

Astrology, astronomy, and the use of mathematics to correlate the positions of the stars and planets, Moon and the Sun relative to the Earth's position was first used to predict the weather.

Many professors of mathematics were judicial astrologers, who invented algebra, geometry, trigonometry and calculus.

Among the Judicial Astrologers of Note are -


Just a few judicial astrologers who did NOT have a problem knowing that astrology is the mother of astronomy and that the transits of the celestial bodies influences all organic life on Earth.

The use of mathematics came directly from astrological use to correlate positions of the celestial bodies relative to the Earth.


Those having a "problem" with this should revisit their "perception" and "definition" of astro-LOGY - by name itself - a science.

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