John Philoponus - Life

Life

Possibly born into a Christian family, nothing is known of his early life. Philoponus 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.

Philoponus’ 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 movement when that energy is exhausted. In this erroneous but insightful theory can be found the first step towards the concept of inertia in modern physics, although Philoponus’ theory was largely ignored at the time because he was too radical in his rejection of Aristotle.

But this 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 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

In 529 Philoponus wrote his critique 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’ major preoccupations and dominated several of his publications (some now lost) over the following decade.

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 story of creation using the insights of Greek philosophers and Basil the Great. 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’ 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 Philoponus made some theological contributions to the Council of Constantinople concerning Christology. His doctrine on Christ’s duality, according to which in Christ remain two united substances, united but divided, is analogous to the union of the soul and body in human beings and coincides with the miaphysite school of thought. He also produced writings on the Trinity around this time.

After his death, John Philoponus was declared to have held heretical views of the Trinity and was made anathema in 680-1. This limited the spread of his ideas in the following centuries, but in his own time and afterwards he was translated into Syriac and Arabic, and many of his works continued to persevere and be studied by the Arabs. Some of his works continued to circulate in Europe in Greek or Latin versions, and influenced Bonaventure. The theory of impetus was taken up by Buridan in the 14th century.