John Philoponus

Quick Facts

• Lived: ca. 490-ca. 570 CE
• Place: Alexandria, in Byzantine Egypt
• Also called: John the Grammarian; "Philoponus" means something like "lover of toil"
• Main fields: Aristotelian commentary, natural philosophy, Christian theology, logic
• Best known for: criticizing Aristotle on motion, rejecting the eternity of the world, and defending Christian creation with philosophical arguments

The Big Question

Can Christian creation and serious Greek natural philosophy fit together when Aristotle says the world and motion are eternal?

Philoponus' answer is yes, but only if Aristotle is treated as a great thinker who can be wrong. He thought reason, observation, and Christian belief all point toward a created world with one physical order, not an eternal cosmos split into divine heavens above and changing earth below.

In One Minute

John Philoponus was a sixth-century Christian philosopher in Alexandria. He was trained in the late antique commentary schools, where students learned philosophy by reading Aristotle line by line. But he did not stay inside the usual rule that old authorities had to be harmonized.

His most famous move was to attack Aristotle's physics. Aristotle said a thrown stone keeps moving because the surrounding air somehow pushes it along. Philoponus said that gets the case backward: air resists the stone. The thrower gives the stone a temporary internal power to move. Later writers called this kind of idea "impetus."

He also argued that the world had a beginning. Against Proclus and Aristotle, he said an actually infinite past would produce impossible results, such as completed infinite series of heavenly revolutions. For Philoponus, God creates the whole material world, and the heavens are not divine or made of a special eternal stuff.

What They Taught

Philoponus taught that Aristotle should be read carefully, but not obeyed blindly. This was bold in his setting. Late antique commentators often tried to show that Aristotle, Plato, and the older philosophers agreed at the deepest level. Philoponus kept the discipline of close commentary, but used it to show where Aristotle's explanations failed.

His physics starts from ordinary cases. If an arrow flies after it leaves the bow, the moving cause is no longer touching it. Aristotle said the displaced air circles around and pushes the arrow from behind. Philoponus replies that air slows projectiles down. The arrow must instead receive a moving power from the bow. This power is not a little body inside the arrow. It is an impressed force or activity that explains why the arrow keeps going for a time.

This does not make Philoponus a modern Newtonian. He did not teach the modern law of inertia, and he still thought the impressed power could be used up. But he shifted the explanation of motion from the surrounding medium to the moving body itself. That made motion in a void, or empty space, thinkable. If air is not the thing that keeps an object moving, then empty space is not impossible just because there is no air to push the object.

Philoponus also attacked Aristotle's split between the changing earthly region and the perfect heavenly region. Aristotle said the heavens are made of a fifth element, often called aether, which is unlike earth, water, air, and fire. Aether was supposed to be unchanging and naturally suited to eternal circular motion. Philoponus denied that the stars and heavens need this special divine material. They are bodies in the same created order as everything else.

His creation argument is just as important as his physics. "Eternity of the world" means the claim that the cosmos has no first moment. Philoponus argued that this is not just a religious problem. If the heavenly spheres have been revolving forever, then an infinite number of revolutions has already been completed. But a completed actual infinity, he says, cannot be counted through, increased, or multiplied. If one sphere turns faster than another, an eternal past would give us different completed infinities of revolutions. Philoponus thought that was absurd even by Aristotelian standards.

For Philoponus, creation means that God brings the world into being. Creation out of nothing means God does not merely arrange pre-existing matter, like a builder arranging stones. God gives being to matter itself. Natural causes inside the world do not create from nothing, but God is not just another natural cause inside the world.

Key Ideas With Examples

• Impetus-like motion: an object can keep moving because a mover has given it a temporary moving power. Example: a stone continues forward after leaving your hand because the throw has impressed motion into the stone, not because the air is secretly pushing it.

• Medium and void: a medium is the material through which something moves, such as air or water; a void is empty space. Aristotle made the medium help explain motion and rejected the void. Philoponus made the medium mainly a source of resistance, so empty space became more thinkable.

• Aether: Aristotle's special fifth element of the heavens. Philoponus rejected the need for it. Example: the sun and stars do not have to be divine, unchanging bodies made from a higher substance.

• Actual infinity: an infinite collection treated as already complete. Philoponus denied that the past can be an actual completed infinity. Example: if the moon has completed infinitely many revolutions before today, then the world has already crossed an infinite series of earlier events.

• Creation out of nothing: God creates matter itself, not only the shape or order of matter. Example: this is not like making a table from wood; it is the existence of wood, table, space, and time depending on God.

Major Works

• Commentary on Aristotle's Physics: his most famous work for the history of science. It criticizes Aristotle on projectile motion, falling bodies, place, void, and the role of the medium.

• Commentary on Aristotle's On the Soul: treats light as active rather than as a static state of transparency, helping explain how light can warm bodies.

• Commentary on Aristotle's Meteorology: pushes against Aristotle's account of the heavens and celestial bodies.

• On the Eternity of the World Against Proclus (529): a detailed reply to Proclus, who defended the eternal world. Philoponus reads Plato's Timaeus as a real creation account and defends creation out of nothing.

• On the Eternity of the World Against Aristotle (ca. 530-534): a lost work preserved in fragments, especially through Simplicius. It attacks Aristotle's fifth element, eternal motion, and eternal time.

• On the Creation of the World (De opificio mundi): a commentary on Genesis that brings biblical creation into conversation with Greek philosophy and applies impressed motion to the heavens.

• Arbiter (Diaitetes): a later theological work on Christ and the Trinity that uses Aristotelian terms inside Christian doctrinal debates.

Why It Matters

Philoponus matters because he shows a late antique philosopher openly breaking Aristotle's authority from inside the Aristotelian commentary tradition. He does not simply say, "Christianity says otherwise." He tries to beat Aristotle and Proclus with arguments about motion, infinity, matter, and the heavens.

He also matters for the long history of science. His account of projectile motion is not modern physics, but it was a serious step away from the idea that motion always needs a continuously touching mover. For Christian philosophy, he is a major example of someone trying to make creation intellectually rigorous: the world is not a divine animal or an eternal machine, but a created order that can be studied with reason.

Proponents, Critics, and Opponents

Philoponus' main philosophical opponents were Aristotle, Proclus, and the late antique Neoplatonism that defended an eternal cosmos. Simplicius attacked Philoponus fiercely; ironically, his quotations helped preserve parts of Philoponus' lost anti-Aristotelian work.

Later readers in Syriac and Arabic philosophy kept his arguments in circulation. Islamic Falsafa inherited debates about Aristotle, creation, and the finite past, and al-Kindi used arguments close to Philoponus when defending a temporally finite world.

In the Latin West, thinkers such as Bonaventure cared about arguments for creation and against an eternal world. Later medieval motion theory developed in directions that resemble Philoponus' impressed-force idea.

Philoponus also became controversial in Christian theology. His later views on the Trinity and Christ were condemned after his death, even though his arguments about creation and nature continued to matter.

Related Pages

• Aristotle
• Proclus
• Neoplatonism
• Islamic Falsafa
• al-Kindi
• Natural Philosophy
• Bonaventure
• Timaeus