The Copernican Question: Prognostication, Skepticism, and Celestial Order

by Robert S. Westman

In 1543, Nicolaus Copernicus publicly defended his hypothesis that the earth is a planet and the sun a body resting near the center of a finite universe. But why did Copernicus make this bold proposal? And why did it matter? The Copernican Question reframes this pivotal moment in the history of science, centering the story on a conflict over the credibility of astrology that erupted in Italy just as Copernicus arrived in 1496. Copernicus engendered enormous resistance when he sought to protect astrology by reconstituting its astronomical foundations. Robert S. Westman shows that efforts to answer the astrological skeptics became a crucial unifying theme of the early modern scientific movement. His interpretation of this long sixteenth century, from the 1490s to the 1610s, offers a new framework for understanding the great transformations in natural philosophy in the century that followed.

Genres: Science, History, History Of Science, Nonfiction

704 pages, Paperback

First published July 2, 2011

Reviews

[Tlaura · Rating 3 out of 5]

This big, big summer-reading-project length book is full of fascinating insights about the social and intellectual foundations of modern cosmology as they emerged in the sixteenth century, particularly as reactions to Copernicus' masterwork De Revolutionibus. Westman has been one of the field's major experts over the past 40 years and so his work is important almost by definition. In particular, his straightforward unapologetic style of describing pre-scientific ideas (rather than trying to fit them into a grant progressive narrative of increasingly rationalist philosophy) is still bracing and rewarding.

Some caveats: at 700+ pages the book really could have used some editing. Westman sometimes takes his anti-positivism a bit far and at unnecessary length. I'm not convinced the sort of person who is going to wade through The Copernican Question really needs to be lectured (in the intro) about how "scientist" or even "natural philosopher" are anachronistic terms in the context of sixteenth century thought. Westman instead introduces new terms like "heavenly practitioner" that don't, as far as I can tell, really improve on "mathematician" but do add an unpleasant sense of pedantry to the proceedings.

I also don't think Westman establishes his thesis, which is that Copernicus adopted the heliocentric arrangement in order to establish the planetary ordering in response to the criticisms of astrology offered up in 1496 by the count Pico della Mirandola. Pico and his commentators did criticize the uncertainties in existing astronomical theory, and in particular the inaccuracy of the Alphonsine Tables, as part of their assault on astrology. But I don't entirely understand from Westman's discussion how establishing the period-distance rule in the Copernican ordering was going to effectively counter that criticism. And of course it didn't touch the most important criticism of judicial astrology advanced by Pico but also by less erudite religious traditionalists: that it constrained both God and man's free will and so was impious.

Even on the strictly technical level, Ptolemaic astronomers were already good at predicting eclipses, so the biggest problem arising from inaccuracy of the planetary tables had to do with house cusps in making nativities. I was therefore surprised to learn from Westman that there was no major attempt among sixteenth century intellectual astrologers to do away with the traditional zodiac, since this would have gotten them around the house-cusp problem and also discarded the most glaringly pagan elements of astrology. Kepler did just that of course, but he attributed the rejection of houses and signs to other people, of which Pico was only one. It would have been useful, and probably more convincing in terms of his thesis, for Westman to have provided a more focused intellectual history of astrological practice between Pico and Kepler, addressing the status of signs and the different emerging physical explanations of astrological effects (and how they differed from astral magic). There is in fact lots of interesting stuff on this topic in the book, but it's scattered throughout the text, mixed in with discussions of patronage and social roles of practitioners, and doesn't really add up to a coherent history of ideas.

As a smaller point, or all his sensibility to Renaissance intellectual culture (and sometimes fussy anti-positivism), Westman still occasionally makes what strike me as presentist assumptions. For instance, he argues that Kepler rejected the infinite universe proposed by his friends Wacker and Edmund Bruce because it would ruin his theory of the aspects. But I don't exactly see why Kepler's astrology required a sphere of fixed stars. Surely his belief in the closed universe had more do do with his conception of the archetypical structure of the heavens, the trinity as reflected in the sphere, and probably also to the anti-mathematical, anti-empirical views of infinitists like Bruno. Westman also offers up semi-psychological analyses of Rheticus' and Galileo's characters (including a lot of fairly pointless rumination about what Galileo felt about Kepler) that clash with his usually sensitive historicism.

So The Copernican Question is an imperfect book. There's still loads of good stuff in it, and in a way its imperfections and contentious bits make it a more fun read. I especially enjoyed the parts about Reinhold's difficulties in getting the Prutenic Tables funded and about Offucius' Timaeus-inspired cosmology, all of which was fairly new to me. Westman mostly ignores the recent work on history of cometary theory and Stoic cosmology by Barker and Goldstein which would have made an interesting complement to the story told here. But overall to read this book is to gain an understanding of sixteenth century intellectual culture that you're unlikely to find anywhere else in comparable richness, detail or with comparable historical sensitivity. Importantly, that's true whether or not you accept Westman's the Picoian origin of heliocentrism or not.