The pre-Socratic intellectual tradition is thought to have begun with Thales of Miletus of the Ionian school. There are two other pre-Socratic schools: the Italians and Athenians. The Italian philosophers, who were Greeks intellectuals living in Italy, consist of three key thinkers: Pythagoras (c. 582 – c. 497 BC), Parmenides (510-450 BC), and Zeno (490-430 BC). The major unifying factor in the Italian school was their incorporeal monism. They held that all things consist of a single intangible substance; this distinguished them from the Ionians who taught that a tangible substance lay behind all things.
Pythagoras, believed to have been a charismatic teacher, is perhaps the most reputable advocate of this school. He lived most of his life in Italy after moving there with colonizing Greek forces, and had a fascination with numbers and music theory. He believed that the fundamental reality of all things is immaterial, which he claimed is mathematics, thus positing numbers to be the basic rational principle behind all things. He advocated religious rituals, self discipline, and emphasized the idea of the transmigration of the soul. He held the soul to be immortal, and that it goes through a series of reincarnations.
Parmenides contended that the human ideas of space, time, and motion are illusory. Things can’t change in quantity (i.e. in height) or quality (i.e. from hot to cold). He claimed that whatever exists does so in a fixed, eternal, and unchanging reality known as being. Thus, those who believe that things around them change are deceived and living in an illusion. He famously coined the phrase that “whatever is… is.”
Zeno was a student and popularizer of Parmenides known for his paradoxes. He intended to prove Parmenides’s idea that space, time, and motion are illusory, and therefore absurd. He did this by presenting three paradoxes: the paradox of the runner, the tortoise and the hare, and the arrow. The paradox of the runner, for example, presents a scenario that before a runner completes running 100 meters, he must run 50. But to run 50 meters he must run 25, then 12.5, and so on. No matter how far the runner has to run he has to run half that distance. The distance is infinitely divisible so that ultimately the runner cannot run at all for it gets smaller and smaller until it gets to the point where the runner cannot move.
The Athens were corporeal pluralists who held to the notion that multiple physical substances constitute the world, or constitute the fundamental elements of the world. Three are particularly important: Empedocles (495-435 BC), Anaxagoras (500-428 BC), and Democritus (460-371 BC).
Empedocles is well-known for having championed Athenian democracy, which gelled well with his corporeal pluralism given that democracy is itself pluralistic (it consists of different, diverse people and groups vying for control and power). Famously, Empedocles died in an active volcano on Mount Aetna, but not before being the first person in history to maintain that light traveled at a fixed speed. Most importantly he proposed that there are four elements which make up everything: earth, air, fire, and water. He referred to these as “roots,” which he said are eternal and unchanging. Empedocles also wished to discover the essence behind the essences, namely a fifth essence or ‘quintessence.’
Anaxagoras, a friend of Empedocles living in Athens during the Persian wars, believed there were an infinite number of separate and distinct elements, which he referred to as ingredients or seeds. The original state of the cosmos was a mixture of all its ingredients. These ingredients are shifted, separated, and remixed with each other, and produced a cosmos consisting of separate material masses and objects. Anaxagoras also introduced the notion of the ‘nous’ (the mind), which he claimed is the motive cause and governing principle of the cosmos. The nous is different from the ingredients that constitute the original mixture, and it set everything in motion and rotation. It set in motion the rotation of the mass of ingredients, and controls this rotation. Anaxagoras did not identify the nous with the gods.
Democritus would have been a contemporary of Socrates, and he was the first atomist (‘atom’ from the Greek ‘atomos,’ meaning indivisible or not cuttable). He posited atoms to be the fundamental substances of all things. Atoms are infinite, unchangeable, hard, indestructible, and always moving endlessly through the void (empty space). They also come in different shapes and sizes, and repel one another when they collide in the void. They can also combine into clusters through the use of tiny hooks on their surfaces. Democritus believed that human beings and the role had arisen from the collision of atoms moving about, and will likewise disintegrate in time.