Was Copernicus an Astrologer?

Abstract

The question ‘Was Copernicus an astrologer’ is prima facie very clear, while in fact being quite ambiguous. This question should rather be regarded as a vast topic covering lots of more concise questions such as ‘Was Copernicus thoroughly educated in astrology?’, ‘Did Copernicus believe in astrology?’ or ‘Did a mature Copernicus practice astrology?’ Unfortunately, thus far, consensus has not been achieved among historians on any of them. Accordingly, the topic has been for some time, and still is, a battlefield of the most acrimonious debates in Copernicology, nay, perhaps in the whole history of science. Carefully made distinctions and subsequent analysis of the common pro et contra arguments enabled this paper to arbitrate the different perspectives. None of the arguments has been found to have a decisive force. In general, while the pro lines of reasoning are normally based upon insecure or even faulty inductive logic, their contra counterparts often suffer from ex silentio inferences or even ad ignorantiam fallacy. Two new, subtle arguments have been introduced instead. They can be considered as genuine new evidence allowing for the resolution of some lingering doubts. First, the natal charts of Copernicus that were cast in the middle of the 16th century have been studied. The excessively exact birth hour of Copernicus at 4:48 PM has quite naturally been expected to be a result of a preliminary astrological rectification. However, apparently it was not rectified by the algorithms most popular at the time. The findings suggest the number-symbolic rather than astrological inclinations of Copernicus. Further, a careful analysis of Copernicus’s annotations in the Alfonsine Tables revealed a link between the misprints corrected by him and the ancient observations he included in De Revolutionibus. Consequently, an extensive astrological use of the tables by him can be excluded with a high probability. Moreover, Copernicus likely never used Regiomontanus Tables on a regular basis either. The conclusion integrates all the available arguments pertinent to the relationship of Copernicus with astrology.