Occasio dubitandi. Expressions of Trust and Distrust Between Latin Medieval Astronomers (13th–15th c.)

Abstract This paper investigates the construction of trust in scientific inquiries and defends the importance of social epistemology in 13th century Parisian astronomy. A major issue in ancient and medieval astronomy is attributed to the difficulty of acquiring precise first-hand knowledge of astral phenomena, making collective work necessary, but raising concerns about trusting second-hand knowledge. The paper begins by examining Ptolemaian epistemology, in its moral and cognitive aspects. It then turns to the late Middle Ages, a challenging period for astronomy, marked by significant changes between the 13th and 14th centuries. Manuscript Paris, Bnf, Latin 7281, containing William of Saint-Cloud’s Almanach planetarum , is presented as key evidence. William there offers innovative astronomical insights, while expressing concerns that his ideas might provoke doubt among his opponents. The final part deals with a marginal gloss by an anonymous 15th-c. annotator who expresses reservations about William but also surprisingly echoes his epistemic stance.