Important Pre-Socratic Schools

The first pre-Socratic philosophers existed in the city of Miletus, along the western coast of Anatolia (modern Turkey). From Miletus came three important pre-Socratic philosophers: Thales, Anaximander, and Anaximenes.


One of the most important pre-Socratic philosophers, Thales (624-546 s.c), claimed the arche, or the single element, was water. Thales determined that water could experience principles of change like evaporation and condensation, therefore allowing Oct it to be gaseous or solid. He also knew that water was responsible for moisture (which heat was generated from) and nourishment. Thales even believed the earth floated on water.


The last important pre-Socratic philosopher of the Milesian school was Anaximenes (585-528 B.c.), who believed the single element was air. According to Anaximenes, air is everywhere and has the ability to undergo processes and become transformed into other things, such as water, clouds, wind, fire, and even the earth.


Following Thales, the next major philosopher to come out of Miletus was Anaximander (610-546 B.O. Unlike Thales, Anaximander claimed the single element was actually an undefined, unlimited, and indefinite substance, known as apeiron. From this, opposites like moist and dry and cold and hot separated from each other. Anaximander is known for being the first philosopher that we know of to have left writings of his work.

Philosopher and mathematician Pythagoras (570-497 B.c.), perhaps most famous for the Pythagorean theorem named after him, believed that the basis of all reality was mathematical relations and that mathematics governed everything. To Pythagoras, numbers were sacred, and with the use of mathematics, everything could be measured and predicted. The impact and image of Pythagoras was astounding. His school was cult-like, with followers listening to his every word … and even his strange rules, which covered anything from what and what not to eat, how to dress, and even how to urinate. Pythagoras philosophized on many areas, and his students believed that his teachings were the prophecies of the gods.

The Ephesian school was based on the work of one man, Heraclitus of Ephesus (535-475 B.c.). Heraclitus believed that everything in nature is constantly changing, or in a state of flux. He is perhaps most famous for his notion that one cannot step in the same river twice. Heraclitus believed that the single element was fire and that everything was a manifestation of fire.

The Eleatic school was based in Colophon, an ancient city not far from Miletus. From this region came four important pre-Socratic philosophers: Xenophanes, Parmenides. Zeno, and Melissus. 

Parmenides of Elea

Parmenides (510-440 B.c) believed reality didn’t have to do with the world one experienced and that it was only through reason, not the senses, that one would be able to arrive at the truth. Parmenides concluded that the work of earlier Milesian philosophers was not only unintelligible; they were asking the wrong questions to begin with. To Parmenides, it made no sense to discuss what is and what is not, for the only intelligible thing to discuss, and the only thing that is true, is what is (what exists). Parmenides had an incredible impact on Plato and all of Western philosophy. His work led the school of Elea to become the first movement to use pure reason as the only criterion for finding truth.

Xenophanes of Colophon

Xenophanes (570-475 B.c) is known for his critique of religion and mythology. In particular, he attacked the notion that the gods were anthropomorphic (or took a human form). Xenophanes believed there was one god that, while it did not physically move, had the ability to hear, see, and think, and controlled the world with his thoughts.

Melissus of Samos

Melissus of Samos, who lived around 440 e.c., was the last philosopher of the Eleatic school. Continuing the ideas of Pa rmenides and Zeno of Elea, Melissus of Samos distinguished between is and seems. When a thing is X, according to Melissus of Samos, it has to always be X (and never not X). Therefore, according to this idea, when something is cold, it can never stop being cold. But since this is not the case, and properties are not retained indefinitely, nothing (except for the Parmenidean Real, reality existing as one continuous, unchanging thing) actually ever is; rather, it seems.

Zeno of Elea

Zeno of Elea (490-430 B.c) was Parmenides’ most famous student (and possibly his lover), who devoted his time to creating arguments (known as paradoxes) that defended Parmenides’ ideas. In Zeno’s most famous paradoxes, the paradoxes of motion, he attempted to show that ontological pluralism, the notion that many things exist as opposed to one, will actually lead to conclusions that are absurd. Parmenides and Zeno believed that reality existed as one thing, and that things like plurality and motion were nothing more than illusions. Though the work of Zeno would later be disproved, his paradoxes still raise important questions, challenges, and inspirations for philosophers, physicists, and mathematicians.

The Atomist school, started by Leucippus in the fifth century e.c. and passed down by his student, Democritus (460-370 B.c), believed that every physical object is made up of atoms and void (empty space that atoms move in) that are arranged in different ways. This idea is not too far from the concepts of atoms that we know today This school believed that atoms were incredibly small particles (so small that they could not be cut in half) that differed in size, shape. motion, arrangement, and position, and that when put together, these atoms created what is seen in the visible world.