The Byzantine Philosopher of Creation Who Started the Scientific Revolution
How John Philoponus Liberated Natural Philosophy from Aristotle and paved the way for Modern Science
Image: John Philoponus, bishoysblog.com
Around the year 500, during the Late Roman Empire, the Classical tradition of Aristotle’s physics and cosmology was an intellectual monolith that appeared unassailable. Everyone with any intellectual sophistication knew that according to science there were five elements (earth, air, fire, water, and aether), that the planet Earth and the solar system were eternal, that there was no such thing as a vacuum, and that it was impossible for motion to be imparted from one object to another (a concept known as impetus or inertia). Aristotle and his philosophical tradition had soundly established all of these axioms over a thousand years earlier, and it was up to the contemporary teachers of science and philosophy to simply repeat the “truth” and make it clear to the next generation.
Such was not the case, however, with the Alexandrian Christian philosopher, mathematician, scientist, and theologian, John Philoponus. In a culturally and philosophically unprecedented move, Philoponus, inspired by the Biblical understanding of creation, resolutely resolved to refute Aristotle and took on the entire tradition of Aristotelian natural science. In a series of scathing commentaries and ingenious treatises, Philoponus questioned the existence of aether, argued for a unified theory of light and time, philosophically demonstrated the reality of a vacuum in space, proposed a unified theory of natural law that governs the cosmos, invented the idea of inertia, and argued against the eternity of the universe.
His work was the basis for that of Buridan, Oresme, Al-Ghazali, Cusa, Copernicus, Galileo, Kepler, Steno, Boyle, Newton, Maxwell, and all others who would work to break with the Aristotelian tradition of physics. The ideas of Philoponus “anticipated by a thousand years the advent of a new age,” and all succeeding generations of modern scientists follow in his footsteps.1
A Christian Philosopher Among the Neo-Platonists
Philoponus was born of Christian parents in Alexandria Egypt around the year 490. Mentored by Ammonius Hermiae, who had studied in Athens under the famous philosopher Proclus, Philoponus received his education at the pagan Neo-Platonist school of Alexandria, which, in the Late Roman Empire was rising to preeminence over the more ancient Academy of Athens. Under Ammonius, Philoponus received instruction on Plato and Aristotle and was taught the astronomy of Ptolemy.
Philoponus and his Christian friends (which included Severus of Antioch, the future Christian Patriarch of Alexandria) spent their days engaging in charitable works and participating in philosophical discussions with the Neo-Platonist pagans at their school. Philoponus struggled to reconcile many of the philosophical and scientific teachings of Aristotle with his Christian faith. As he rose in prominence as a teacher of philosophy at the age of twenty-seven, he started writing a series of commentaries on Aristotle’s work. Eventually, Philoponus would distinguish himself as one of the most brilliant logicians of the ancient world and one of the last great commentators of Aristotle.2
A Philosophic Renegade Who Parted Ways with Aristotle
In his commentaries on Aristotle Philoponus began to defy established tradition and clashed with the established philosophical culture of his age. For over a thousand years philosophy had been passed down from age to age through commentaries that emphasized the authority of the great philosophers, whose wisdom remained unsurpassed. Philosophical commentators within this venerable pagan tradition were expected to demonstrate the essential agreement between Plato and Aristotle and to confirm that harmony existed between all the ancient philosophers, from Homer down to the time of Aristotle.
Philosophers in the late Roman Empire, within which Philoponus lived, developed and propagated their own ideas within the context of commentaries on the classical philosophical texts of Plato and Aristotle. In a rich and unbroken tradition, generations of such commentaries were written from the time of the early Roman Empire, when Aristotle’s works became again accessible to a wider audience, through the time of the Byzantine Empire and beyond.
“Doing philosophy in this way was not only an education, it was also and even more so a pagan religious exercise, empowering thinkers to perfect their intellect and their character with a view to becoming godlike as far as is humanly possible.”3 Within this established intellectual culture it was completely unheard of—and irreligious—to criticize the pagan philosophical greats or to question their authority.
Philoponus began his career as a teacher of philosophy in the usual way by writing such conventional commentaries on the works of Aristotle, but in time he would begin to do something unprecedented—he “transformed the usual format of commentary sympathetic to Aristotle’s views into a discourse of open criticism.”4 Creating a new style of philosophical commentary that was “doggedly disrespectful of authority,” Philoponus issued an open critique of Aristotle, examining and repudiating fundamental Aristotelian-NeoPlatonic tenets.
With a “remarkable freedom of spirit that allowed him to cast off the fetters of authority as a criterion of truth,” Philoponus drew conclusions that were at odds with a thousand years of respected knowledge and used novel examples for instructive purposes which demonstrated both his command of logic and the creativity of his scientific imagination.5 Such a “renegade approach to philosophical tradition, as well as the conclusions of his arguments, antagonized Philoponus’ pagan colleagues,” and their “fierce enmity” eventually “compelled him to abandon his philosophical career in the 530s.”6
The End of Aristotle’s Aether and the Unity of Physical Law
Image: Aristotle, history.com
Aristotle’s philosophical science asserted that there existed a fifth element (after earth, air, fire, and water) that he called “aether”. While the four terrestrial elements were changeable and transient, Aristotle contended that the planets, stars, and objects beyond the Earth were eternal and thus must be constructed of a different—and eternal—substance that transcended the earthly four. Inspired by the Biblical book of Genesis—and Basil the Great’s commentary on Genesis—Philoponus insisted on “the unity of heaven and earth” and argued that the material and forces of the celestial realm were akin to those on the terrestrial realm. According to Philoponus, the same elements on Earth were to be found in the outer space beyond Earth.
In a provocative publication entitled, On the Eternity of the World against Aristotle, Philoponus closely scrutinized Aristotle’s On the Heavens and rejected his theory of aether as the fifth element, of which the heavenly bodies are made. In this work, Philoponus sought to defend the Biblical view of creation and endeavored to remove scientific obstacles for those who affirm Scripture’s account.7 If, argued Philoponus, “Aristotle were right about the existence of an immutable fifth element (aether) in the celestial region, and if he were right about motion and time being eternal, any belief in creation would surely be unwarranted.”8
In response, Philoponus dissected Aristotle’s texts in an unprecedented way and demonstrated numerous inconsistencies, contradictions, fallacies, and improbable assumptions in Aristotle’s philosophy of nature relating to the aether.9 Harnessing the internal logic of Biblical monotheism as it relates to cosmology, Philoponus argued that heaven and earth were both created by God ex nihilo with no distinction or dichotomy between a sublunar region and a heavenly region. In particular, Philoponus endeavored to “disprove by physical considerations Aristotle’s belief that the sun and the stars consisted of aether, and claimed that they were sources of fire of the same kind as terrestrial fires, being like those subject to creation and decay.” Philoponus argued that “all matter everywhere is nothing but tri-dimensional extension and in this respect, too, there is no difference between heaven and earth.”10
The End of Aristotle’s Theory of Motion and the Invention of Inertia
Dismantling Aristotle’s theory of aether, Philoponus went on to demolish his physical theory of motion. According to Aristotle, all motion is a result of where the material of a given object “wants” to go in accordance with its essential elemental nature. Thus, the element earth wants to fall down, the element air wants to rise up, and the element aether wants to go in perfect circles. Aristotle believed that pure motion could never be imparted from one object to another and that the mover and moved must always be in some type of contact. Thus, in the case of projectile motion, Aristotle concluded that the air displaced in front of a projectile somehow rushed around it and pushed it from behind, propelling the projectile along.
Philoponus’ commentary on Aristotle’s Physics offers a scathing array of innovative counter-examples where he develops the theory of impetus, which is a decisive step away from Aristotle and towards the modern theory of inertia. Philoponus considers the question of why an arrow continues to fly after it has left the bow-string, or why a stone continues to fly after it has ceased to be in contact with the hand that throws it. Instead of Aristotle’s theory of continuous pushing, Philoponus proposed that a projectile moves on account of a kinetic force (an impetus) that is impressed on it by the mover and which exhausts itself in the course of the movement.
Having explained projectile motion in terms of an impetus, Philoponus then reassessed the role of the medium within which a projectile flies. He concluded that the medium of air, far from being responsible for the continuation of a projectile’s motion, is in fact an impediment to it. From here Philoponus goes on to argue, against Aristotle, that there is in fact nothing to prevent one from imagining such imparted motion taking place through a void or a vacuum. Appealing to the same kind of scientific experiment that Galileo was to carry out a thousand years later, Philoponus then also rejects Aristotle’s view that the speed of bodies falling through a medium is proportional to the weight of the moving bodies and indirectly proportional to the density of the medium. Instead, he asserts, that in a vacuum or void two objects of different weight will fall at the same speed.
The Contradiction at the Heart of Aristotle and the Impossibility of Eternity
Having undermined Aristotelian mechanics of motion, Philoponus discovered a contradiction at the heart of Aristotle’s physical cosmology that went unnoticed for almost a thousand years—namely Aristotle’s contention that the physical world is eternal while at the same time holding that an actual infinity cannot logically exist. Philoponus demonstrated that if the cosmos is uncreated and has no beginning (as Aristotle argued), then an actual infinity of years must have passed. If the world is eternal, then an infinite number of moments must have been traversed. However, if the infinite has been traversed, then it is not truly the infinite (because infinity is a limit that can never be reached).11
Because Aristotle rejected the idea of an infinite series of causes as a logical contradiction, his view of the eternity of the world was, in fact, a logical contradiction. Philoponus then used this paradox of infinity to prove the world had to have a beginning, that this beginning was of the same ex nihilo nature as that described in Genesis’s creation narrative, and that the universe must have been created by a transcendent God. As Philoponus pioneered a type of cosmological argument for the existence of God that eventually came to be known as the Kalam cosmological argument, he left the cosmological system of Aristotle in ruins.12 Philoponus’ discovery of this “contradiction at the heart of paganism…between their concept of infinity and their denial of a beginning” was a key “turning point in the history of philosophy,” which constituted the end of the classical era and the dawn of the modern age.13
Shmuel Sambursky, Physical Thought from the Pre-Socratics to the Quantum Physicists: An Anthology (Pica Press, 1975) 4.
For example, historians of logic acknowledge that Philoponus was “the first to render a satisfactory account of the syllogism (subsequently the traditional one), stating that the major premise includes the predicate term of the conclusion, the minor premise the subject term.” He was also the first to schematize a type of diagram, that would become known as the ‘asses’ bridge’ (pons asinorum), which enabled students of logic more easily to construct valid syllogisms. Christian Wildberg, “John Philoponus,” The Stanford Encyclopedia of Philosophy (Fall 2021 Edition), Ed. Edward N. Zalta.
Wildberg, “John Philoponus,” The Stanford Encyclopedia of Philosophy.
Christian Wildberg, “John Philoponus,” Routledge Encyclopedia of Philosophy Volume 7, Ed. Edward Craig (Routledge, 1998) 369.
Wildberg, “John Philoponus,” Routledge Encyclopedia of Philosophy, 370.
Wildberg, “John Philoponus,” Routledge Encyclopedia of Philosophy, 369.
Christopher Kaiser, Creational Theology and the History of Physical Science, 30-31.
John Philoponus, Philoponus, Against Aristotle on the Eternity of the World (Duckworth, 1987).
Wildberg, “John Philoponus,” Routledge Encyclopedia, 374.
Sambursky, Physical Thought, 45.
Richard Sorabji, Time, creation and the continuum: theories in antiquity and the early middle ages (Duckworth, 1983), 198.
Following the Islamic conquest of Byzantine Alexandria, the kalam cosmological argument of Philoponus was taken up and enriched by medieval Muslim and Jewish theologians and philosophers. In the 11th century, the Persian Islamic philosopher Al-Ghazali contended that the notion of eternal causation is intrinsically nonsensical, and that maintaining such an eternity would be tantamount to maintaining the causelessness of the universe. A century later in Spain, the Jewish philosopher Maimonides extended this line of reasoning to argue that a proof of the existence of a single incorporeal and necessary cause would constitute a genuine proof of the existence of God. The devout Christian mystic and early astronomer Johannes Kepler similarly understood the fact of causation and the paradoxes of infinity as pointing to God, and he developed a version of the cosmological argument that was aided by his scientific reflections on the nature of stars. Going back to an argument from the dark sky that was first put forward by John Philoponus, in 1610 Kepler pointed out that an infinite Universe that is infinitely old—as suggested by Giordano Bruno—would have an infinite number of stars. Consequently, the night sky of an infinite universe should be completely bright. Why, then, is it mostly dark? Kepler’s answer is that the universe is finite in both distance and time, because it had a beginning, and ultimately owes its origin to God.
Richard Sorabji, Philoponus and the Rejection of Aristotelian Science (Cornell University Press: 1987), 220.