John Philoponus


Philosopher, Theologist, Mathematician, Physicist, Astronomer, Writer (c.490 – c.570)

John Philoponus was a Christian Neoplatonic and Aristotelian philosopher, philologist, scientist and theologist. His name means “friend of pain”, which denotes his love for hard work. Considered by many as the most educated man of his time, John Philoponus was a prolific writer, whose bibliography spans the fields of philosophy, mathematics, physics, logic, metaphysics, psychology, astronomy, theology and cosmology. Primarily renowned for his works in physics, he was the first scientist to propose the experiment of the fall of two bodies of different weight to disprove Aristotle’s long lasting theory that the heaviest of the two bodies would fall first.

Philoponus studied philosophy in the Neoplatonic School of Alexandria. His teacher, Ammonius, headmaster of the school, was a student of Proclus, one of the most influential philosophers in world history. Later on, Philoponus became a scholar in the same school and began writing commentaries on Aristotle’s works. As he started distancing himself from Aristotle’s axioms, he moved on to writing his own original treatises, unwillingly becoming one of the first critics of Aristotle and introducing his own new concepts and ideas in philosophy, a very daring act at the time.

In the field of physics, Philoponus disagreed with Aristotle that light is a static property and instead proposed that light is an immaterial action capable of heating up bodies. In a similar way, he asserted that the soul warms up the body. He deduced that light travels from light-emitting objects to the eye by means of geometric optics. Furthermore, he explained that heat is produced from the sunlight’s rays that refract and heat up the air by means of friction.

Philoponus rejected Aristotle’s theory that any three dimensional object must be a material body, redefined the concepts of void and matter, researched collisions and compiled studies on free fall. In particular, he described that during free fall of two bodies of different weight, the difference in their time of fall is not equal to the proportion of their weight, but in reality is very small. Moreover, he made significant contributions to the theory of impetus and in inertia, which changed the direction of dynamics towards a more modern form that it has today.

Concerning astronomy, he applied the theory of impetus on the celestial bodies, claimed that the sun and the stars are made of fire, that planets do not spin in perfect circular symmetry and that celestial bodies are three-dimensional. He attempted to provide an explanation for the creation of the galaxy and the universe and, while a Christian, he accepted Plato’s Timaeus of the creation of the universe as being in harmony with the Christian dogma.

Philiponus’ studies on physics influenced several scientists of the Renaissance. The most notable example was Galileo. In his first texts, Philoponus’ name is mentioned more times than Plato’s name. Galileo praises him for his ideas, most importantly on his theory of impetus, which helped Galileo develop his theory on the inertia. In addition, one can find numerous similarities between the two scientists, such as both questioning Aristotle’s theories, both believing that man will never be fully able to understand any natural phenomenon and both being condemned by the Church as heretics.

As an open-minded philosopher, his theses were not accepted by the Church or his colleagues. Accused of rejecting the dogma of the Trinity and being a tritheist, Philoponus was condemned by the Church. His sentence was revocated in 1990.

Philoponus’ works had a significant influence on Islamic, Judaic and Christian thought. They were subsequently translated into Arabic, Latin and Syrian. Perhaps his greatest achievement was that he made his thought independent from that of Aristotle, challenging the philosopher’s authority, thus allowing physics as a science to progress. His scientific genius has recently been compared to that of Isaac Newton and Galileo by modern scientists.


  1. Ιακώβου, Μαρία. Η Φυσική του Ιωάννη Φιλόπονου και ο Γαλιλαίος, Πτυχιακή Εργασία. Αριστοτέλειο Πανεπιστήμιο Θεσσαλονίκης, Σχολή Θετικών Επιστημών, Τμήμα Φυσικής. Web.
John Philoponus

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