John Hennon

Who is John Hennon?

John Hennon was a medieval philosopher in the late Scholastic tradition. He was from Nijmegen, and studied at the University of Paris, where he received his magister artium and baccalaureus formatus in sacra pagina.

As a student of Paris, Hennon was heavily influenced by William of Ockham and Roger Bacon. He wrote a Latin commentary on the Physics of Aristotle, the Commentarii in Aristotelis libros Physicorum, which was completed on 1 October 1473 if a seventeenth-century source is to be believed. Examining the state of science in the late Middle Ages, physicist, historian, and philosopher Pierre Duhem, in Le système du monde, isolates Hennon's account of the vacuum and a plurality of worlds.

Hennon believed that nature abhors a vacuum and therefore no natural void was possible, though God could create one. A void, however, is not defined by a positive distance between surfaces in which there is nothing, but rather as the capacity for a body to be interposed between the two surfaces equal to that which is there when it is full. Hennon affirms that ice is denser than liquid water, and that a sealed vase of water will break upon freezing because nature abhors a vacuum.