John Philoponus
490?-570
Byzantine Scholar
Known also as Johannes Philoponus and John the Grammarian, the Byzantine scholar John Philoponus wrote on a variety of subjects, from theology to physics. Most notable among his writings was his critique of Aristotle's ideas regarding motion: whereas his great predecessor had incorrectly maintained that a body in motion requires a continued application of force to remain in motion, Philoponus held that a body will keep moving in the absence of friction or opposition.
Philoponus grew up in Alexandria, Egypt, where he studied under Ammonius Hermiae (fl. c. 550), a well-known commentator on the ideas of Aristotle (384-322 B.C.). As a student, Philoponus was one of the first to attempt a synthesis between Aristotelian thought and Western spiritual beliefs. Later other thinkers—including the Christian Thomas Aquinas (1225?-1274), and before him the Muslim Ibn Rushd (Averroës; 1126-1198) and the Jew Moses Maimonides (1135-1204)—would attempt a similar synthesis, but Philoponus was centuries ahead of them. In particular, he was one of the very first to identify Aristotle's idea of the First Cause with the Christian God, a notion that would become highly influential when Aquinas expressed it more than half a millennium later.
Much of Philoponus's work concerned Aristotle: thus he produced commentaries on the Physics, Metaphysics, Organon, De anima (On the soul), and De generatione animalium (On the generation of animals). The subjects of these works varied between issues of science and theology, a range reflected in the career of Philoponus himself. Though his greatest historical importance today lies in his scientific discussion of the Physics, his most significant work in his lifetime was Diaitetes e peri henoseos (Mediator; or concerning union), a discussion of the nature of Christ and the Trinity.
In the latter he maintained that every being has a singular nature, and thus Christ could only be divine, not human as well. This placed him dangerously close to the heresy known as Monophysitism, and though Philoponus attempted to exonerate himself with logical acrobatics, the Third Council of Constantinople censured him in 681. By then, however, Philoponus was long dead, and thus did not suffer as a result of his flirtation with heretical thought.
Just as he proved forward-thinking in his attempts to reconcile Aristotle with the Bible, Philoponus was even more ahead of his time in his critique of Aristotelian views on motion. According to Aristotle's kinetic theory, an object does not move unless an external force acts on it, and it can only remain moving as long as that force continues to be applied. According to this explanation, wind and air themselves act as a form of propellant. Philoponus, on the other hand, held that velocity is proportional to the positive difference between force and resistance—i.e., the force must be greater than the resistance—and that the body will remain in motion as long as the former exceeds the latter.
One can see this principle in action by observing a ball in motion. As Aristotle had maintained, the ball cannot move unless an external force acts on it: for instance, a person must pick up the ball and roll it across the floor. (Aristotle's theory, of course, makes no sense when discussing an animate being such as a person or animal.) Initially the ball has considerablymore force than the resistance of the floor, which will be lesser or greater depending on the floor's covering: in other words, marble would provide amuch easier rolling surface than carpet. As the ball rolls, however, the resistance becomes increasingly greater than the force (actually, modern physicists would call this kinetic energy) of the rolling ball, and eventually it comes to a stop.
The preceding is an illustration of the first law of motion formulated by Isaac Newton (1642-1727). Before Newton, however, there was Jean Buridan (1300-1358), who held that one object imparts to another a certain amount of power, in proportion to its velocity and mass, that causes the second object to move a certain distance. This was an accurate and prescient observation, as was Buridan's position that air resistance slows an object in motion.
But even before Buridan there was Peter John Olivi (1248-1298), credited as the first Western scholar to challenge Aristotle's erroneous notions on kinetics; and before Olivi came was Ibn Sina (Avicenna; 980-1037), like Philoponus a devotee of Aristotle who nonetheless broke with the latter's teachings on matter in motion. Yet long before all these was Philoponus himself, who also challenged the Aristotelian (and indeed Greco-Roman) view that all persons reflect a universal mind. It was Philoponus's position, as would become the view of modern man, that each person is an individual possessed of a separate intellect.
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