The Presocratics were a group of diverse thinkers who rose in the Greek-speaking world in the 6th and 5th centuries. They are considered the first philosophers in the Western canon and they produced a diverse range of theories that sought to explain the nature of the universe. Philosophers at this point in time were not only practicing philosophy in the modern sense. They were also astronomers, mathematicians, physicists, social scientists, and more. Besides, these were philosophers in the literal sense of the word as “friends of wisdom.” The foundations of science and philosophy were laid with these early thinkers.
The Term “Pre-Socratics” & Connection to Socrates
- Meaning: Presocratics (Pre-Socratic)s refers to the early Greek philosophers who lived before Socrates (5th century BCE).
The term Presocratics was coined in the 18th century CE by scholars interested in Greek philosophy. However, it was popularized by Herman Diels in the 19th century. Diels used this term to highlight the distinction between these thinkers, whom he believed were interested in natural phenomena, and Socrates, who was primarily concerned with moral philosophy. Nevertheless, the presocratics were also interested in moral and political problems. Moreover, although presocratics literally means “before Socrates,” many of the thinkers classified as Presocratics were contemporaries of the famous Greek philosopher Socrates.
One thing that links all the Presocratics is that their work is lost. In contrast to Plato and Aristotle, who were lucky enough to have large parts of their work preserved, the Presocratics are now accessible only through fragments of their work surviving in the work of later authors.
The rest of this article is a list of 13 Presocratic philosophers with information about their lives and philosophical theories. All quotes in the form of fragments are taken from Kathleen Freeman’s Ancilla to the Pre-Socratic Philosophers.
The Milesians
1. Thales Of Miletus (c.625-c.546 BCE)
Key Takeaways:
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Believed water is the origin of all matter.
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Used geometry to solve real-world problems like measuring pyramids.
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Considered the first Western philosopher by Aristotle
Thales from the city of Miletus in Asia Minor was interested in natural philosophy. Aristotle considered Thales to be the first philosopher in the Greek tradition and, consequently, of the Western canon. The Milesian was additionally included amongst the seven sages of Greece.
Thales proposed a system in which water was considered the origin of all matter. In addition, he famously predicted the solar eclipse of 585 BCE and introduced geometry from Egypt to Greece, as well as other inventions. Thales calculated the height of Egypt’s pyramids and the distance of ships from the shore using geometry. He is also attributed with developing the ‘Thales Theorem.’
Like most of the Presocratics, and especially those from Miletus, Thales was not just a philosopher but an individual seeking knowledge in every corner he could reach. He was a mathematician, astronomer, engineer, and so much more.
Key Quotes: No quotes are attributed to Thales.
2. Anaximander Of Miletus (c.610-c.546 BCE)
Key Takeaways:
- Introduced the Apeiron (the infinite) as the source of all things.
- Possibly drew the first map of the known world.
- Early thinker on evolution and multiple worlds.
Also active in the city of Miletus was Anaximander, a student of Thales. Anaximander was one of the first philosophers to write a book. Like Thales, he was also interested in many different areas. He is attributed with the invention of the gnomon, although that is highly unlikely.
Anaximander was also thought to be the first to draw a map of the known world. He disagreed with his teacher regarding the basic substance of the universe. While Thales believed that everything came out of the water, Anaximander attributed everything to the Apeiron (literally translates as “the infinite”). This was an abstract entity that gave birth to everything and was the place where all things returned.
Anaximander was also the first to use the term arche (beginning) in a philosophical context. Additionally, he speculated that animals and humans evolved out of other animals that live in the water and believed in the existence of multiple worlds.
Key Quote:
- “The Apeiron is the original material of existing things.”
3. Anaximenes Of Miletus (c.586-c.526 BCE)
Key Takeaways:
- Proposed air as the fundamental substance.
- Believed changes in density create different forms.
Anaximenes was the third Milesian. He was a student of Anaximander and was also a monist. Where Thales saw water and Anaximander the Apeiron, Anaximenes saw air, which he thought was the arche (beginning) of all things.
Key Quote:
- “Air is near to the incorporeal; and since we come into being by an efflux from this (air), it is bound to be both non-limited and rich so that it never fails.”
Heraclitus and Xenophanes
4. Heraclitus Of Ephesus (c.535-c.475 BCE)
Key Takeaways:
- Taught that everything flows; change is constant.
- Introduced the unity of opposites and early dialectics.
- First to use the concept of the Logos (rational principle).
Heraclitus was born in Ephesus of Asia Minor, where he produced a philosophy of change. He believed that the world is made of fire and is always moving. For Heraclitus, nothing ever remains the same, a philosophy which is summed up in the phrase “Panta Rhei” (everything flows). His most famous quotes are about this idea of a universe in constant change and movement (see the river quotes below).
Another important part of his philosophy is his idea of the unity of opposites. This meant that for Heraclitus, opposites like good and bad, being and non-being, night and day, up and down, were in fact one. Not one as indiscernible, but as in the way that a coin has two sides. This idea is also considered the origin of dialectic thought.
He is also the first Greek philosopher to talk about the Logos, a term that became extremely popular in the next centuries and continues to be one of the most central terms for philosophers even today.
Heraclitus is said to have left only one work, called On Nature, which was particularly influential. In later centuries, he became known as the “weeping philosopher” because many of his fragments appeared pessimistic to scholars. He was also called the “Obscure philosopher” because of his cryptic sayings. Plato, Nietzsche, Hegel, Heidegger, and even communist leader Lenin were fans of the Ephesian philosopher.
Key Quotes:
- “This ordered universe (cosmos), which is the same for all, was not created by any one of the gods or of mankind, but it was ever and is and shall be ever-living Fire, kindled in measure and quenched in measure.”
- War is both king of all and father of all, and it has revealed some as gods, others as men; some it has made slaves, others free.
- When you have listened, not to me but to the Law (Logos), it is wise to agree that all things are one.
- The famous river quotes:
- It is not possible to step twice into the same river.
- “Those who step into the same river have different waters flowing ever upon them.”
- “In the same river, we both step and do not step, we are and we are not.”
5. Xenophanes Of Colophon (c.570-c.478 BCE)
Key Takeaways:
- Criticized anthropomorphic gods of Greek tradition.
- Believed in one god that was not like humans.
- Early advocate of relativism and epistemic humility.
Just like all of the Presocratics, Xenophanes was not your typical philosopher. He was a poet and theologian who spoke firmly against the idea of polytheism. Xenophanes criticized the theological views of Homer and Hesiod who painted an immoral image of gods who committed theft, adultery and more. He also believed that the gods were not like humans and that there was only one non-anthropomorphic deity.
Xenophanes was also among the first to discuss the limits of human knowledge. He spoke of the impossibility of understanding the truth about the gods and insisted that knowledge is relative. As a result, he was one of the first relativists in history.
Key Quotes:
- “If God had not created yellow honey, they would say that figs were far sweeter.”
- “Aethiopians have gods with snub noses and black hair, Thracians have gods with grey eyes and red hair.”
- “But if oxen (and horses) and lions had hands or could draw with hands and create works of art like those made by men, horses would draw pictures of gods like horses, and oxen of gods like oxen, and they would make the bodies (of their gods) in accordance with the form that each species itself possesses.”
The Pythagorean Tradition
6. Pythagoras of Samos (c.575-c.490 BCE)
Key Takeaways:
- Founded a mystical school centered on numbers and asceticism.
- Promoted reincarnation and the soul’s immortality.
- Attributed with the Pythagorean Theorem and music theory.
The philosopher Pythagoras was born on the Greek island of Samos. At c. 530 BCE, he moved to Croton in South Italy to found his school. Pythagoras is one of the most interesting presocratics, existing somewhere between myth and history.
It is difficult to talk about Pythagoras. His school in Croton was a secret society with teachings accessible only to those initiated. As a result, the beliefs of the society’s members, the Pythagoreans, are not really clear. However, we do know that Pythagoras’s school taught an ascetic way of life that demanded dietary restrictions and promoted a spirituality that idolized numbers and math, called numerology.
In many ways, Pythagoras was more like a prophet than a philosopher, and his school more like a monastery. The ascetic life, the communal lifestyle, the obsession with the divine meaning of numbers, and the miracles attributed to Pythagoras are enough proof of that. Aristotle tells us that the people in Croton called Pythagoras “Hyperborean Apollo” and that once in Olympia, he revealed his thigh, which was made out of gold. A central idea in Pythagorean thought was the belief in metempsychosis, the reincarnation of the soul after death.
Pythagoras is also attributed with a series of scientific achievements that could or could not actually be his, like the Pythagorean theorem, the Pythagorean tuning in music, the theory of Proportions, the spherical shape of the earth, and more.
Socrates, Plato, Aristotle, the Neoplatonists, and many presocratic thinkers were heavily influenced by Pythagoras and his tradition.
Key Quotes*:
- “The soul of man is divided into three parts, intelligence, reason, and passion. Intelligence and passion are possessed by other animals, but reason by man alone.”
- “Reason is immortal, all else mortal.”
*Pythagoras did not leave any written works. None of the available quotes can be attributed to him with certainty. These quotes were attributed to him by Diogenes Laertius (2nd to early 3rd century BCE) a few centuries after Pythagoras’ death.
The Eleatics: Greek Philosophers Against Movement
7. Parmenides of Elea (end of 6th-beginning of 5th century BCE)
Key Takeaways:
- Argued that change is an illusion; being is unchanging.
- Denied the reality of sensory perception.
- Claimed truth can only be known through reason.
Parmenides was the founder of the Eleatic school and one of the most influential early Greek philosophers. Plato wrote a dialogue called Parmenides, where it is stated that a young Socrates met Parmenides when he was around 65 years old in Athens.
Parmenides wrote only one book, and only a poem from this work is preserved. This contains extremely difficult and abstract philosophical ideas regarding the nature of being. These ideas are in complete opposition to the ones found in the work of the Ionian philosophers. Furthermore, it seems that the Greek philosopher had serious doubts regarding the possibility of obtaining the truth about the world using our senses.
In many ways, Parmenides is the complete opposite of Heraclitus. Where Heraclitus talked of change and movement, Parmenides insisted on an unchanging, stable universe. While Heraclitus emphasized that the world is a Becoming, Parmenides held that what exists is part of the one that is timeless, uniform, unchanging, immovable, indestructible, and perfect.
Key Quote:
- “…the one that it is, and it is not possible for it not to be, is the way of credibility, for it follows Truth; the other, that it is not, and that it is bound not to be: this I tell you is a path that cannot be explored; for you could neither recognise that which is not, nor express it.”
8. Zeno Of Elea (c.495-c.430 BCE)
Key Takeaways:
- Created paradoxes to deny motion and plurality.
- Defended Parmenides’ idea of a static reality.
- Famous for the “halfway paradox”.
Zeno was a student of Parmenides and his successor as the head of the Eleatic school. According to Plato’s dialogue Parmenides, Zeno met young Socrates when he visited Athens with Parmenides to present his book.
In antiquity, Zeno became famous for his paradoxes that sought to prove that all motion and change were illusions. With these paradoxes, Zeno was trying to prove the ontological theories of his teacher that the world was uniform, unchanging, and immovable.
Aristotle discussed these paradoxes in detail, offering entertaining insights into Zeno’s thought. One of the paradoxes, as described by Aristotle, is the following:
“The first (paradox) asserts the non-existence of motion on the ground that that which is in locomotion must arrive at the half-way stage before it arrives at the goal.”
In a few words, Zeno claims that to cover a distance, someone has to cover half of the distance first. But since we can keep dividing distance in half ad infinitum, it is not possible to move from any point to another.
Key Quote:
- “That which moves, moves neither in the place in which it is, nor in that in which it is not.”
- “If Things are Many, they must be as many as they are and neither more nor less than this. But if they are as many as they are, they must be finite (in number).”
The Pluralists
9. Empedocles Of Acragas (c.494-c.434 BCE)
Key Takeaways:
- Taught that the universe is made of four elements.
- Introduced Love and Strife as cosmic forces.
- Advocated vegetarianism and reincarnation.
The presocratic philosopher with the most bizarre stories surrounding his death is without a doubt Empedocles of Acragas. In one story, he disappeared into the heavens at night, and in another, he leaped into the volcanic crater of Mount Etna. Most probably, though, none of these stories is true.
Inspired by the Pythagoreans, Empedocles is an almost messianic figure. In one story, it is said that he resurrected a woman who had stopped breathing. Of course, these stories tell more about popular imagination than Empedocles himself.
He was influenced by the philosophy of Parmenides and was the last of the Greek philosophers to express his ideas in verse. Empedocles denounced animal sacrifices and advocated vegetarianism alongside a theory of reincarnation (metensarcosis).
He also taught that there are four elements: fire, air, water, and earth. Everything in existence is a transformation of these four elements. Two powers, Strife and Love, are responsible for the different ratios of each of these elements in things. Strife makes the elements withdraw to themselves, while Love makes them unite.
Key Quotes:
- “(God) is equal in all directions to himself and altogether eternal, a rounded Sphere enjoying a circular solitude.”
- “At one time it (the Being) increased so as to be a single One out of Many; at another time it grew apart so as to be Many out of One—Fire and Water and Earth and the boundless height of Air, and also execrable Hate apart from these, of equal weight in all directions, and Love in their midst, their equal in length and breadth. Observe her with your mind, and do not sit with.”
10. Anaxagoras Of Clazomenae (c.500-c.428 BCE)
Key Takeaways:
- Proposed that Nous (Mind) organizes all matter.
- Explained reality as infinite fragments mixed and separated.
- Exiled for impiety due to natural explanations of celestial events.
Anaxagoras wrote only one book, and he was mainly influenced by the theories of Parmenides. However, his own theory was a reaction to the Eleatic monism.
According to Anaxagoras, in the beginning, everything existed in infinitely small fragments and in infinite numbers in such a small place and in such close proximity that they were almost indiscernible. The rearrangement of these fragments was orchestrated by the cosmic mind, which he called Nous.
Anaxagoras spent a good part of his life teaching in Athens. Like Socrates, he was one of the Greek philosophers to undergo a trial for their ideas. The Athenians blamed him for impiety, probably because of his views that rejected the existence of lunar and solar deities. Pericles, the Athenian politician, defended Anaxagoras in his trial as the two of them were friends. In the end, Pericles advised Anaxagoras to leave Athens, and the philosopher left for Lampsacus, where he died.
Key Quote:
- “The Greeks have an incorrect belief on Coming into Being and Passing Away. No Thing comes into being or passes away, but it is mixed together or separated from existing Things. Thus they would be correct if they called coming into being ‘mixing’, and passing away ‘separation-off’.”
Greek Philosophers Of The Atomic Theory
11. Leucippus of Miletus (in his prime c.430 BCE)
Key Takeaways:
- First to theorize atoms as indivisible building blocks.
- Asserted motion requires a void (non-being).
- Believed natural laws, not randomness, govern the universe.
Today, when we hear of the atomic theory, our mind directly goes to nuclear weapons and power plants. However, the philosophical theory of atomism is much, much older. In fact, it is as old as Leucippus, the first of a series of Greek philosophers called the atomists.
Leucippus claimed that everything is made of tiny indivisible things called atoms, which literally translates as “those which cannot be cut”. A core point in his theory is that for movement to be possible, a vacuum needs to exist. In a few words, for being to exist, there must be non-being.
In many ways, Leucippus continued the naturalistic Ionian philosophy of Thales, Anaximander, Anaximenes, and Heraclitus. Furthermore, he was the first to claim that things are the way they are because of their nature. Leucippus established a philosophical school at Abdera and according to a story, he founded the city of Metapontum.
Key Quotes:
- “Nothing happens at random; everything happens out of reason and by necessity.”
- He may have been the first to use the term “atom” (uncuttable) to refer to the indivisible primary matter.
12. Democritus of Abdera (c.460-c.370 BCE)
Key Takeaways:
- Developed detailed atomic theory with various atom shapes.
- Valued reason over sensory knowledge.
- Known as the “laughing philosopher” for promoting cheerfulness.
Born in Abdera, Thrace, Democritus was a wealthy citizen who traveled extensively during his life. Very commonly, he is listed together with his teacher Leucippus, making it difficult to tell their views apart. He wrote 73 books and led a life that avoided active engagement in politics, although he did give public lectures. Democritus visited India, Egypt, Ethiopia, and Persia, where it is said that he studied under Ostane, a magus in the court of King Xerxes. He is also said to have been initiated into Pythagoreanism at some point in his life and to have briefly studied next to Anaxagoras.
Like his teacher, Democritus insisted that matter is made of indivisible parts called atoms that interact mechanically with each other. He also believed that there were atoms of different sizes and shapes. For example, he held that air atoms were different from iron atoms and that these differences dictated their interaction. Democritus also valued the intellect as a valid source of knowledge and cautioned against relying solely on truths obtained through the senses. We know that he made some contributions in the fields of aesthetics, mathematics, biology, anthropology, and other sciences. Like many Greek philosophers, he also believed in the existence of multiple worlds.
Democritus became known in antiquity as the “laughing philosopher,” in contrast to Heraclitus, the “weeping philosopher.” That was because of his emphasis on the value of cheerfulness. Although his political and ethical thinking is not reconstructable, we know that Democritus advocated for a life of moderation, where a certain degree of hedonism was acceptable.
Key Quotes:
- “(I would) rather discover one cause than gain the kingdom of Persia.”
- “atoms and Void (alone) exist in reality”.
- “If one oversteps the due measure, the most pleasurable things become most unpleasant.”
Sophists: The Greek Philosophers That Socrates Despised
13. Protagoras of Abdera (c.490-c.420 BCE)
Key Takeaways:
- Famous for “Man is the measure of all things” doctrine.
- Emphasized relativism and doubted objective truth.
- Took an agnostic stance on the existence of gods.
The sophists were a group of teachers experienced in philosophy who, according to Plato, mainly supported the view that there is no objective truth. Protagoras was one of the most important representatives of this movement and a student of Democritus.
In the dialogue of Plato called “Protagoras”, the Greek philosopher Socrates debates the nature of virtue with Protagoras. Although Plato was not fond of the sophists in general, he presents Protagoras as a respected thinker.
Protagoras believed that for everything, there were always two arguments of equal strength. As a result, he began to seriously doubt the possibility of obtaining objective truth. For this reason, Protagoras is considered one of the most important thinkers in the history of relativism. In addition, Protagoras took a seemingly agnostic stance on the issue of the existence of gods.
This agnosticism brought Protagoras to a difficult position as the Athenians banished him from the city and burned all copies of his books. Although he respected Protagoras, Socrates oftentimes spoke against the sophists and their axiom that there is no single truth.
Key Quotes:
- “Of all things the measure is Man, of the things that are, that they are, and of the things that are not, that they are not.”
- “About the gods, I am not able to know whether they exist or do not exist, nor what they are like in form; for the factors preventing knowledge are many: the obscurity of the subject, and the shortness of human life.”
