John (Johannes) Hennon (died after 1484) was a Dutch

medieval philosopher Medieval philosophy is the philosophy that existed through the Middle Ages, the period roughly extending from the fall of the Western Roman Empire in the 5th century until after the Renaissance in the 13th and 14th centuries. Medieval philosophy, ...

in the late Scholastic tradition. He was from

Nijmegen Nijmegen (;; Spanish and it, Nimega. Nijmeegs: ''Nimwèège'' ) is the largest city in the Dutch province of Gelderland and tenth largest of the Netherlands as a whole, located on the Waal river close to the German border. It is about 6 ...

, and studied at the

University of Paris , image_name = Coat of arms of the University of Paris.svg , image_size = 150px , caption = Coat of Arms , latin_name = Universitas magistrorum et scholarium Parisiensis , motto = ''Hic et ubique terrarum'' (Latin) , mottoeng = Here and a ...

, where he received his ''

magister artium A Master of Arts ( la, Magister Artium or ''Artium Magister''; abbreviated MA, M.A., AM, or A.M.) is the holder of a master's degree awarded by universities in many countries. The degree is usually contrasted with that of Master of Science. Tho ...

'' and '' baccalaureus formatus in sacra pagina'' (1463). As a student of Paris, Hennon was heavily influenced by William of Ockham and

Roger Bacon Roger Bacon (; la, Rogerus or ', also '' Rogerus''; ), also known by the scholastic accolade ''Doctor Mirabilis'', was a medieval English philosopher and Franciscan friar who placed considerable emphasis on the study of nature through empiri ...

. He wrote a

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

commentary on the ''

Physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

'' of

Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of phil ...

, 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 Pierre Maurice Marie Duhem (; 9 June 1861 – 14 September 1916) was a French theoretical physicist who worked on thermodynamics, hydrodynamics, and the theory of elasticity. Duhem was also a historian of science, noted for his work on the Euro ...

, in ''Le système du monde'', isolates Hennon's account of the

vacuum A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often dis ...

and

a plurality of worlds ''Conversations on the Plurality of Worlds'' (french: Entretiens sur la pluralité des mondes) is a popular science book by French author Bernard le Bovier de Fontenelle, published in 1686. Content The work consists of six lessons popularizing ...

. Hennon believed that

nature abhors a vacuum In physics, horror vacui, or plenism (), commonly stated as "nature abhors a vacuum", is a postulate attributed to Aristotle, who articulated a belief, later criticized by the atomism of Epicurus and Lucretius, that nature contains no vacuums bec ...

and therefore no natural

void Void may refer to: Science, engineering, and technology * Void (astronomy), the spaces between galaxy filaments that contain no galaxies * Void (composites), a pore that remains unoccupied in a composite material * Void, synonym for vacuum, a s ...

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 (''potentialitas'') 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. He believes further that two smooth plates could not be separated (again, because nature abhors a vacuum) unless there were some air still between them, which with enough force may become

rarefied Rarefaction is the reduction of an item's density, the opposite of compression. Like compression, which can travel in waves (sound waves, for instance), rarefaction waves also exist in nature. A common rarefaction wave is the area of low relativ ...

, allowing the plates to be separated. Hennon is less original on a plurality of worlds, where he borrows text verbatim from

Albert of Saxony en, Frederick Augustus Albert Anthony Ferdinand Joseph Charles Maria Baptist Nepomuk William Xavier George Fidelis , image = Albert of Saxony by Nicola Perscheid c1900.jpg , image_size = , caption = Photograph by Nicola Persch ...

's ''Quaestiones in libros de Caelo et Mundo''. He follows Albert and

John Buridan Jean Buridan (; Latin: ''Johannes Buridanus''; – ) was an influential 14th-century French philosopher. Buridan was a teacher in the faculty of arts at the University of Paris for his entire career who focused in particular on logic and the wo ...

in asserting that a multiplicity of worlds is not contradictory and therefore possible through divine omnipotence. In fact, God could create an infinite multitude of beings, since Hennon finds no contradiction between

infinity Infinity is that which is boundless, endless, or larger than any natural number. It is often denoted by the infinity symbol . Since the time of the ancient Greeks, the philosophical nature of infinity was the subject of many discussions amo ...

and magnitude. Duhem in his analysis of Hennon's chapter ''De Caelo et Mundo'', argues that Hennon relied on the Condemnations of 1277 by

Stephen Tempier Stephen or Steven is a common English first name. It is particularly significant to Christians, as it belonged to Saint Stephen ( grc-gre, Στέφανος ), an early disciple and deacon who, according to the Book of Acts, was stoned to death; h ...

to attack Aristotelian physics, and thus the position that the earth cannot move.Hennon refers to the specific article of condemnation ''Quod Deus non posset movere Caelum motus recto, error'': "That God could not move the heavens with

rectilinear motion Linear motion, also called rectilinear motion, is one-dimensional motion along a straight line, and can therefore be described mathematically using only one spatial dimension. The linear motion can be of two types: uniform linear motion, with co ...

, an error".

Notes

Sources

Further reading