Exploring the Roots of Western Philosophy: The Pre-Socratic Period

Around 600 BCE, on the western coast of what is now Turkey, something extraordinary happened in human thought. For centuries, the Greeks had explained the world through myth – thunder was Zeus’s anger, the sea’s fury was Poseidon’s wrath, and the cosmos itself was born from the union of primordial gods. Then a group of thinkers from the city of Miletus quietly but decisively changed the question. Instead of asking “which god caused this?”, they began asking “what is this made of, and why does it behave the way it does?” That shift – from mythos (myth) to logos (reason) – marks the true beginning of Western philosophy.

What is the Pre-Socratic period? 🔗

The term “Pre-Socratic” refers to the Greek thinkers who worked before or independently of Socrates (c. 470-399 BCE). According to Britannica, pre-Socratic philosophy encompasses the cosmological and naturalistic speculations of ancient Greek philosophers who were predecessors or contemporaries of Socrates. The Stanford Encyclopedia of Philosophy describes them as the first philosophers and scientists of the Western tradition – thinkers who introduced an entirely new way of inquiring into the world and the place of human beings in it.

Because the earliest Greek philosophers focused their attention on the origin and nature of the physical world, Aristotle called them physiologoi – meaning “natural philosophers” or “physicists of nature.” In earlier literature, they were also referred to as physikoi, after the Greek word physis, meaning “nature.” The period spans roughly the 6th to 5th centuries BCE, and while many figures contributed to it – including Heraclitus, Pythagoras, Parmenides, and Democritus – its earliest and most foundational chapter belongs to the thinkers of Miletus.

The world before the Pre-Socratics: myth as explanation 🔗

To understand what the Pre-Socratics achieved, it helps to appreciate what came before them. In early Greek culture, as in many ancient civilizations, myth was the dominant framework for understanding natural events. Phenomena like thunder and lightning were attributed to divine action, and the cosmos itself was said to have originated from the struggles and unions of gods. Works like Hesiod’s Theogony (c. 700 BCE) gave organized accounts of cosmic origins, but these were rooted in divine genealogy, not natural principles.

The pre-Socratic philosophers rejected these traditional mythological explanations of the phenomena they saw around them, initiating analytic and critical thought instead. Crucially, this was not a wholesale rejection of the divine – many Pre-Socratics still believed the cosmos was in some sense divine or infused with life. The radical shift was methodological: they began privileging natural causality and rational coherence over narrative and divine authority. As the Internet Encyclopedia of Philosophy puts it, the foundation of Presocratic thought is the preference given to rational argument over mythologizing – a movement that would shape the entire course of Western thought.

The Milesian school: where Western philosophy began 🔗

The city of Miletus, situated on the Aegean coast of Ionia (in present-day Turkey), was one of the wealthiest and most cosmopolitan trading centers of the ancient Greek world. Its position as a hub of commerce meant ideas flowed freely between the Greeks, Egyptians, Babylonians, and Phoenicians. The Milesian philosophers – Thales, Anaximander, and Anaximenes – broke with the poetic and mythological tradition handed down by Hesiod and Homer, seeking instead to explain the cosmos on its own terms.

These three thinkers are widely regarded by historians as the first philosophers of the Western world. What united them was their shared commitment to identifying a single arche – a Greek term meaning both “origin” and “principle” – that could explain the diversity of the natural world. They were, in Aristotle’s framework, material monists: each believed that all things ultimately derived from one fundamental substance. They differed, however, on what that substance was.

Thales of Miletus: water as the foundation of all things 🔗

Thales (c. 624-546 BCE) is considered to be the father of philosophy – the first thinker in the Western tradition to use reason, proof, and generalization as tools for understanding reality. He is even credited with coining the word cosmos to describe the universe as an ordered whole. None of his writings survive, but later philosophers, especially Aristotle, preserve his central claim: that water is the fundamental substance from which all things arise.

Why water? Thales likely observed that moisture underlies life – seeds are moist, living things dry out and die, and water appears in multiple states across nature. While this may seem naive by modern standards, the significance of the claim lies not in the answer but in the type of question being asked. Before Thales, the Greeks explained the origin and nature of the world through myths of anthropomorphic gods and heroes; by contrast, Thales attempted to find naturalistic explanations without referencing the supernatural. He also reportedly predicted a solar eclipse in 585 BCE and introduced geometry to Greece from Egypt – evidence that his thinking was grounded in observation and reason.

Thales is also thought to have held that the Earth floats on water, and that nature is a complete and self-ordering system that requires no divine intervention from outside to supplement its account. This idea – that the cosmos has its own internal logic – is perhaps his deepest philosophical legacy.

Anaximander: the boundless as the origin of everything 🔗

Anaximander (c. 610-546 BCE) was a student and successor of Thales, and arguably the more daring philosophical thinker of the two. He was the first Greek philosopher known to have written down his ideas in prose – making his work among the earliest written philosophy in the Western world. He was an early proponent of science and tried to observe and explain different aspects of the universe, with a particular interest in its origins, claiming that nature is ruled by laws, just like human societies.

Anaximander’s key move was to reject Thales’ specific answer while preserving his method. He argued that no single observable substance – not water, not fire, not earth – could serve as the ultimate origin of all things. If water were the original stuff, how would fire come to exist? Something with a specific character cannot generate its opposite without contradiction. His solution was bold: the arche must be the apeiron – a Greek word meaning “the boundless” or “the indefinite.” The apeiron is an endless, unlimited mass subject to neither old age nor decay, which perpetually yields fresh materials from which everything we can perceive is derived.

From the apeiron, opposing qualities – hot and cold, wet and dry – separate out to form the world as we know it. Anaximander also developed an early cosmological model: he was the first to argue that the Earth is not supported by anything beneath it but hangs freely in space, held in position by its equal distance from everything around it. He even produced what is considered the first map of the inhabited world – a remarkable empirical achievement for the 6th century BCE. Perhaps most strikingly, Anaximander speculated that life originated in the sea and that land animals, including humans, descended from aquatic ancestors – a rudimentary evolutionary insight.

Anaximenes: air as the principle of all change 🔗

Anaximenes (c. 585-525 BCE) was a student of Anaximander and the third and last of the Milesian philosophers. Like his predecessors, he sought a single material principle underlying the cosmos. His answer: air. Anaximenes is known for his belief that air is the arche, the basic element of the universe from which all things are created.

What made Anaximenes’ contribution distinctive was not just the choice of air, but the mechanism he proposed for how one substance gives rise to many. Air can apparently take on various properties of color, temperature, humidity, motion, taste, and smell – making it a plausible neutral substrate. More importantly, Anaximenes specified a clear natural process: condensation and rarefaction. When air becomes less dense (rarefies), it turns into fire. When it becomes denser (condenses), it becomes wind, then clouds, then water, then earth, then stone. Condensation would make the air denser, turning it into wind, clouds, water, earth, and finally stone; rarefaction would make it less dense as it eventually becomes fire.

This was a significant philosophical advance: for the first time, a Pre-Socratic had proposed not just what the fundamental substance was, but how it transforms into everything else. The mechanism was natural, observable in principle, and free of any supernatural intervention. What to Thales had been merely a beginning became, through Anaximenes, a fundamental principle that remained essentially the same through all of its transmutations – prefiguring modern ideas about the conservation of matter.

The concept of arche and its lasting importance 🔗

One of the most significant philosophical contributions of the Milesian school is the very concept of arche itself. The term, which originally simply meant “beginning,” acquired the new meaning of “principle” through the Milesian tradition – a term that has played an enormous role in philosophy down to the present. The idea that there is an underlying, persistent principle through all apparent change is the conceptual ancestor of conservation laws in modern physics – from the conservation of mass to the conservation of energy.

The Milesians were also, in Aristotle’s classification, hylozoists – thinkers who believed in a kind of living matter, or matter inseparable from some form of vitality. They did not sharply distinguish between material substances and the forces or qualities that animate them. This blending of the physical and the vital gave their philosophy a distinctly holistic character, quite different from the mechanistic materialism that came later.

From myth to logos: why this shift matters 🔗

The Pre-Socratics are commonly credited with initiating systematic, rational investigation into physis (nature), archê (first principle), and the conditions of knowledge, marking a shift from mythic narratives to explanatory argument. This is not a minor historical footnote – it is one of the most consequential intellectual transitions in human history.

Before the Pre-Socratics, explaining an earthquake meant invoking Poseidon. After them, it became possible – and intellectually respectable – to ask about underground pressures, water movement, and natural forces. This is evident in medicine too: conditions like epilepsy, which popular religion attributed to divine intervention, came to be attributed to nature by Hippocrates’ school, just as Milesian rationalism had demythologized natural phenomena like earthquakes. The Pre-Socratics, in other words, did not just do philosophy – they made science possible.

The shift from mythos to logos also transformed how argument itself was understood. The radical nature of Milesian thinking does not depend on a rejection of all divinity, but a reformation in the way we think about it – replacing stories about gods with principles, replacing inherited narratives with reasoned claims open to debate and revision. This is the spirit that would later animate Socrates, Plato, Aristotle, and the entire tradition of Western philosophy and science.

The Pre-Socratics’ legacy in Western thought 🔗

The Milesian school laid intellectual foundations that extended far beyond their own time. Plato’s metaphysics engaged directly with the question of what truly underlies the changing world. Aristotle built his theory of the four causes in explicit dialogue with the Milesians’ search for a primary substance. The atomists Leucippus and Democritus pushed the Milesian project to its logical conclusion by proposing that all matter is made of indivisible particles – a view that echoes in modern atomic theory. Even the Stoics’ concept of logos as the rational principle governing the cosmos is a direct descendant of the Pre-Socratic project.

Pre-Socratic philosophy is widely regarded as foundational not simply because of specific doctrines, but because of the problems posed and modes of inquiry established – the practice of rational argument, the distinction between appearance and reality, and the idea of philosophy as a distinct, systematic inquiry. These are habits of mind that the West has never abandoned.

It is also worth noting a practical challenge in studying the Pre-Socratics: most of them wrote at least one book, but no complete work survives. We know them through fragments quoted by later writers and through testimonia – reports about their views preserved by Aristotle, Theophrastus, and other ancient philosophers. This means interpretation always involves reconstruction, and scholarly debate about what they actually meant continues to this day.

What do you think? The Milesian philosophers chose water, the boundless, and air as the fundamental substance of everything – all without any experimental equipment, relying purely on observation and reason. Does the choice of a single unifying principle to explain all of reality still make sense as a philosophical goal today? And if the shift from myth to reason was so transformative 2,600 years ago, what assumptions of our own age might future thinkers look back on with the same kind of critical distance?

References

1. https://www.britannica.com/topic/pre-Socratic-philosophy
2. https://plato.stanford.edu/entries/presocratics/
3. https://www.fabriziomusacchio.com/weekend_stories/told/2025/2025-01-03-pre_socratic_philosophy_and_thales/
4. https://en.wikipedia.org/wiki/Pre-Socratic_philosophy
5. https://iep.utm.edu/presocra/
6. https://en.wikipedia.org/wiki/Anaximenes_of_Miletus
7. https://en.wikipedia.org/wiki/Ionian_school_(philosophy)
8. https://en.wikipedia.org/wiki/Anaximander
9. https://philopedia.org/periods/pre-socratic-philosophy/