Anne Lawrence-Mathers’s article “Medieval weather prediction” (Physics Today, April 2021, page 38) is a welcome work of history of science that introduced me to some people and works I had never before encountered. As far as I can judge, it is quite accurate, although Johannes Kepler was surely never a pupil of Tycho Brahe.

It is nonetheless a serious failing of the article to not call attention to the most striking feature of medieval astrometeorology: It did not work. That Eyno of Würzburg claimed to have predicted heavy snow three times is no more an indication of success than an occasional win yielded by a gambler’s system.

In a follow-up online piece (“The triumphs and failures of astrometeorology,” Physics Today online, 30 April 2021, Lawrence-Mathers acknowledges that the theoretical basis of astrometeorology was incorrect but states that, on balance, its contributions to scientific developments were positive. She seems to think the complexity of astrometeorology was a beneficial aspect of it. But astrology, which shared features with astrometeorology, was just as complex. So, was astrology a plus for the development of astronomy? Well, in a way it was, but it was also an obstruction to it.

Kepler knew astrology was nonsense but hoped to improve it. His enhancements were equally nonsensical at first, but they drove him toward creating a really good astronomy. I rate astrology a net negative, but nonetheless, we can acknowledge and learn from the ways it was positive. Similarly, while we can learn from medieval astrometeorology, the predictions it produced “worked” only accidentally. I call that a net negative. There is no arithmetic for weighing the pluses and minuses of history. Any such weighing is therefore a personal judgment.

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Physics Today
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The triumphs and failures of astrometeorology
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