John Philoponus

Later in life Philoponus turned to Christian apologetics, arguing against the eternity of the world in his De opificio mundi, a theory which formed the basis of pagan attacks on the Christian doctrine of Creation. He also wrote on Christology, espousing a miaphysite view. His by-name ὁ Φιλόπονος translates as "lover of toil", i.e. "diligent," referring to a miaphysite confraternity in Alexandria, the philoponoi, who were active in debating pagan (i.e. Neoplatonic) philosophers.

His posthumous condemnation limited the spread of his writing, but copies of his work, Contra Aristotelem, resurfaced in medieval Europe, through translations from Arabic of his quotes included in the work of Simplicius of Cilicia, which was debated in length by Muslim philosophers such as al-Farabi, Avicenna, al-Ghazali and later Averroes, influencing Bonaventure and Buridan in Christian Western Europe, but also Rabbanite Jews such as Maimonides and Gersonides, who also used his arguments against their Karaite rivals. His work was largely debated in the Arabic scholarly tradition, where he is known as Yaḥyā al-Naḥwī (i.e. "John the Grammarian"), and his views against Aristotelian physics were defended by philosophers at the court of Fatimid Imam Al-Hakim bi-Amr Allah, particularly Hamid al-Din al-Kirmani, who debated Avicenna on the topic, and Hamza ibn Ali. His critique of Aristotle in the Physics commentary was a major influence on Giovanni Pico della Mirandola and Galileo Galilei, who cited Philoponus substantially in his works.

Life

Although John Philoponus possibly came from a Christian family, nothing is known of his early life. He studied at the school of Alexandria and began publishing from about 510. He was a pupil and sometime amanuensis to the Neoplatonic philosopher Ammonius Hermiae, who had studied at Athens under Proclus.

According to historian Leslie S. B. Maccoull:

Philoponus, a committed Egyptian Monophysite, chose particular philosophical texts and problems as objects of his work because they were the material of current Monophysite debate. His intention was to provide the nascent Coptic church with a powerful set of tools for argument, with which Egyptian Monophysites could defeat their Chalcedonian opponents.

Philoponus's early writings are based on lectures given by Ammonius, but gradually he established his own independent thinking in his commentaries and critiques of Aristotle's On the Soul and Physics. In the latter work Philoponus became one of the earliest thinkers to reject Aristotle's dynamics and propose the "theory of impetus": i.e., an object moves and continues to move because of an energy imparted in it by the mover and ceases the movement when that energy is exhausted. This insightful theory was the first step towards the concept of inertia in modern physics, preceding Galileo Galilei's supposed supposed experiment at the Leaning Tower of Pisa by centuries. However, his theory was largely ignored at the time because he was too radical in his rejection of Aristotle:

But this [view of Aristotle] is completely erroneous, and our view may be completely corroborated by actual observation more effectively than by any sort of verbal argument. For if you let fall from the same height two weights, one many times heavier than the other you will see that the ratio of the times required for the motion does not depend [solely] on the weights, but that the difference in time is very small. ... — John Philoponus' refutation of the Aristotelian claim that the elapsed time for a falling body is inversely proportional to its weight

Philoponus is the only writer of antiquity to have formally presented such a concept. As the discovery of the principle of inertia is the hallmark achievement of modern science as it emerges in the 16th to 17th centuries, Pierre Duhem argues that its invention would put Philoponus among the "great geniuses of Antiquity" and the "principal precursors to modern science", although he holds it more likely that Philoponus may have received the idea from an earlier, otherwise unrecorded Alexandrian school of mechanics.

We must note that Aristotle himself observes in his Physica (Book IV, Part 8), that "why a thing once set in motion should stop anywhere; for why should it stop here rather than here? So that a thing will either be at rest or must be moved ad infinitum, unless something more powerful get in its way", a very good description of the concept of inertia in vacuum. He does, however, proceed to dismiss this idea on the grounds that a vacuum cannot exist.

In 529 Philoponus wrote his critique On the Eternity of the World Against Proclus in which he systematically defeats every argument put forward for the eternity of the world, a theory which formed the basis of pagan attack of the Christian doctrine of Creation. The intellectual battle against eternalism became one of Philoponus's major preoccupations and dominated several of his publications (some now lost) over the following decade.

He introduced a new period of scientific thought based heavily on three premises: (1) The universe is a product of one single God, (2) the heavens and the earth have the same physical properties, (3) and the stars are not divine. With these principles Philoponus went after his rival, Simplicius of Cilicia, by questioning Aristotle's' view of dynamics and cosmology. He argued that motion can occur in a void and that the velocity of a falling object is not based on its weight. He also held that God created all matter with its physical properties and with natural laws that would allow matter to progress from a state of chaos to an organized state forming the present universe. What remains of his writings indicate that he used the same didactic methods of reasoning that modern science uses and that he performed genuine experiments.

The style of his commentaries and his conclusions made Philoponus unpopular with his colleagues and fellow philosophers, and he appears to have ceased his study of philosophy around 530, devoting himself to theology instead. Around 550 he wrote a theological work On the Creation of the World as a commentary on the Bible’s creation account, using the insights of Greek philosophers and Basil of Caesarea. In this work he transfers his theory of impetus to the motion of the planets, whereas Aristotle had proposed different explanations for the motion of heavenly bodies and for earthly projectiles. Thus, Philoponus's theological work is recognized in the history of science as the first attempt at a unified theory of dynamics. Another of his major theological concerns was to argue that all material objects were brought into being by God (Arbiter, 52A–B).

Around 553 John Philoponus made some theological contributions to the Second Council of Constantinople concerning Christology through his Christological opus magnum, Arbiter. His miaphysite position drew upon Cyril of Alexandria, a point of reference to both miaphysite and Chalcedonian positions, and the miaphysite theologian Severus of Antioch but explicitly contradicted the position of the Cappadocian Fathers and their "rejection of particular natures". As a result, his position was posthumously condemned as "Tritheist" at the Third Council of Constantinople in 680/681.