Pre-Socratic Philosophy

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pre-socratic

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The Greek thinkers of the sixth and fifth centuries BCE who replaced mythic explanation with natural philosophy and gave Western thought its starting categories — matter, principle, change, being.

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Introduction

Pre-Socratic philosophy is the body of Greek thought from roughly 600 BCE to 400 BCE that preceded — and partly overlapped with — Socrates of Athens (c. 470–399 BCE). The label was popularized by Hermann Diels in his 1903 Die Fragmente der Vorsokratiker, the standard collection of surviving texts, and it covers about thirty named thinkers across roughly two centuries. The discipline they founded — the project of asking what the world is fundamentally made of, by what principle it changes, and how human reasoning could establish such things without recourse to traditional myth — is widely treated as the origin of Western philosophy and natural science. The thinkers are studied today both as historical figures and as live interlocutors in metaphysics, epistemology, and the philosophy of science. This entry surveys the period, its central figures, its enduring problems, and its transmission through the fragment tradition.

Founding moment

The conventional founding moment is the work of Thales of Miletus (c. 624–c. 546 BCE) in the early sixth century BCE. Thales is the first thinker recorded as proposing a single underlying principle (Greek archē) for the natural world — water — and as predicting an eclipse, traditionally dated to 28 May 585 BCE. Aristotle, writing more than two centuries later in Metaphysics A (Alpha), identifies Thales as the founder of the type of philosophy that seeks material first principles (Metaphysics 983b6–27). What made Thales' move philosophical, rather than poetic or theological, is two things at once: he asked a general question about the nature of things, and he gave an answer that could be examined and disputed without appeal to authority. Both moves were new.

The setting was the Greek city of Miletus on the Ionian coast of Asia Minor — present-day western Turkey — at a period of substantial cross-cultural contact with Egypt, Babylon, and Phoenicia. Two of Thales' immediate successors, Anaximander (c. 610–c. 546 BCE) and Anaximenes (c. 586–c. 526 BCE), are also Milesians, and the three are conventionally grouped as the Milesian school. The Milesian project — propose an archē, explain natural phenomena from it, argue for or against rival proposals — established the basic shape of inquiry that the rest of the Pre-Socratics extended.

Core doctrines

The Pre-Socratics do not share a single doctrine. They share a project. Five commitments organize that project across most of the thinkers.

First, naturalistic explanation. Phenomena that earlier Greek culture explained by reference to the gods — weather, earthquakes, the heavens, disease — are explained by reference to natural processes, materials, and principles. The Homeric Zeus does not appear in Pre-Socratic causal stories.

Second, the search for archē. The Greek term archē covers both beginning and governing principle; the Pre-Socratics seek what the world fundamentally is and what fundamentally explains its behavior. Candidates include water (Thales), the apeiron or boundless (Anaximander), air (Anaximenes), fire (Heraclitus), what-is or being (Parmenides), the four roots — earth, water, air, fire (Empedocles), seeds or spermata (Anaxagoras), and atoms in the void (Leucippus and Democritus).

Third, the contrast between monism and pluralism. Some Pre-Socratics hold that reality is fundamentally one thing (Parmenides, Melissus). Others hold that it is fundamentally many — either many basic kinds of stuff (Empedocles), many seeds (Anaxagoras), or many indivisible particles (the atomists). The dispute defines the period.

Fourth, the contrast between being and becoming. Heraclitus (c. 535–c. 475 BCE) argues that the world is a process of constant change governed by an underlying logos or rational order. Parmenides of Elea (c. 515–c. 450 BCE) argues, on the contrary, that what is, is, and cannot change, come into being, or pass away — change is illusion, being is the only reality. The Heraclitus–Parmenides dispute is one of the foundational arguments in Western metaphysics.

Fifth, the replacement of myth by logos. The Pre-Socratics inherit a literary culture organized around Homer (eighth century BCE) and Hesiod (eighth–seventh century BCE). They write — sometimes in verse, often in prose — with a different aim: not narration of divine action but argument from principles. Xenophanes of Colophon (c. 570–c. 478 BCE) explicitly criticizes Homeric and Hesiodic theology for projecting human attributes onto the gods.

Major figures

The Pre-Socratics are conventionally organized by school and by problem.

The Milesian school (early to mid-sixth century BCE). Thales (c. 624–c. 546 BCE), Anaximander (c. 610–c. 546 BCE), and Anaximenes (c. 586–c. 526 BCE), all of Miletus. The Milesians propose successive material archai (water; the apeiron; air) and develop the first naturalistic cosmologies.

The Pythagoreans (late sixth century BCE onward). Pythagoras of Samos (c. 570–c. 495 BCE) and his school, centered after about 530 BCE in Croton in southern Italy. The Pythagoreans hold that number and ratio are the fundamental structure of reality, develop a religious-philosophical way of life involving transmigration of souls, and produce work in mathematics, music theory, and astronomy. The surviving Pythagorean fragments are difficult to attribute to individuals; the school left a continuous tradition extending into late antiquity.

The Eleatics (early to mid-fifth century BCE). Xenophanes (c. 570–c. 478 BCE), Parmenides of Elea (c. 515–c. 450 BCE), Zeno of Elea (c. 490–c. 430 BCE), and Melissus of Samos (fl. c. 440 BCE). Parmenides' poem On Nature (composed c. 475 BCE) argues that being is one, eternal, unchanging, and indivisible. Zeno's paradoxes — Achilles and the tortoise, the arrow, the dichotomy — defend the Parmenidean position against the apparent multiplicity of the world.

Heraclitus (c. 535–c. 475 BCE) of Ephesus, who stands apart from any school. His surviving fragments — about 130 sayings preserved in later authors — describe a world of measured change governed by logos. The fragment "you cannot step into the same river twice" (DK 22 B 91) is canonical.

The pluralists (mid-fifth century BCE). Empedocles of Acragas (c. 494–c. 434 BCE) and Anaxagoras of Clazomenae (c. 500–c. 428 BCE). Empedocles' four-roots theory (earth, water, air, fire combined and separated by Love and Strife) and Anaxagoras' seeds-and-Mind theory respond to the Eleatic challenge by allowing fundamental multiplicity without violating the Parmenidean prohibition on coming-to-be and passing-away — what changes is combination, not the basic stuff.

The atomists (late fifth century BCE). Leucippus of Miletus (fl. c. 440 BCE) and Democritus of Abdera (c. 460–c. 370 BCE). The atomists hold that the world consists of indivisible particles (atoma) moving in void. Their account answers the Eleatic challenge by distinguishing being (the atoms) from what-is-not (the void), through which the atoms can move and combine.

The Sophists (mid-to-late fifth century BCE). Protagoras of Abdera (c. 490–c. 420 BCE), Gorgias of Leontini (c. 483–c. 375 BCE), Prodicus, Hippias, Thrasymachus, and others. The Sophists are itinerant teachers of rhetoric, ethics, and politics, often working in Athens during the period of the Peloponnesian War. Whether they belong to Pre-Socratic philosophy is disputed (Plato treats them as antagonists rather than predecessors), but they are included in Diels–Kranz and most modern editions because they share the Pre-Socratic period and inherit its problems.

Major texts

Almost no Pre-Socratic text survives complete. The discipline studies fragments — quotations and paraphrases preserved by later authors — and doxography (reports on what each thinker held).

Texts preserved as fragments. Parmenides' On Nature survives in about 160 lines of verse, embedded in quotations by Simplicius and others. Empedocles' On Nature and Purifications together survive in about 450 lines. Heraclitus survives in about 130 short sayings, scattered across late-antique sources. Anaxagoras and Diogenes of Apollonia survive in fewer than 30 fragments each. Most of the Milesians and most Pythagoreans survive only in doxography, not in direct quotation.

The principal sources for the fragments. Aristotle's Metaphysics A and Physics A; Theophrastus' lost Doctrines of the Natural Philosophers, reconstructed from later excerpts; the Stromata of Clement of Alexandria (late second century CE); Simplicius' commentaries on Aristotle (sixth century CE), which preserve the longest stretches of Parmenides and Empedocles; Diogenes Laertius' Lives and Opinions of Eminent Philosophers (third century CE); Sextus Empiricus' Against the Mathematicians (second century CE).

The standard editions. Hermann Diels' Die Fragmente der Vorsokratiker (first edition 1903), revised by Walther Kranz (sixth edition 1951), is the canonical reference; the numbering system (DK + chapter + A or B + fragment number) is universal. The Loeb Classical Library Early Greek Philosophy in nine volumes (André Laks and Glenn W. Most, 2016) is the current English standard, replacing the partial coverage of earlier collections. Kathleen Freeman's Ancilla to the Pre-Socratic Philosophers (1948) and Daniel W. Graham's The Texts of Early Greek Philosophy (2010) are the standard English-language student editions. For Parmenides specifically, A. H. Coxon's The Fragments of Parmenides (1986, revised by Richard McKirahan 2009) is the scholarly edition.

Internal tensions and rival schools

The Pre-Socratic period is defined by its disagreements. Four are foundational.

Monism versus pluralism. Is reality fundamentally one or many? Parmenides and Melissus argue for one; Empedocles, Anaxagoras, and the atomists argue for many — though each in a way that respects Parmenides' demand that what is real cannot come into being from nothing or pass into nothing. The post-Parmenidean pluralists thus accept Parmenides' negative conclusion (no genuine coming-to-be) while denying his positive conclusion (no genuine multiplicity).

Being versus becoming. Heraclitus holds that everything is in flux; Parmenides holds that nothing is. The dispute structures Plato's Theaetetus (composed c. 369 BCE) and Sophist (c. 360 BCE), Aristotle's discussions of change in Physics A, and substantial portions of contemporary metaphysics.

Material versus structural archē. Most Milesians and the atomists take the archē to be a kind of stuff. The Pythagoreans take it to be number and ratio — structure, not material. The dispute echoes through Plato's theory of Forms (which sides with the Pythagoreans on structure) and through twentieth-century debates about the foundations of physics.

Naturalism versus religion. Xenophanes argues that the gods of Homer and Hesiod are anthropomorphic projections (DK 21 B 11–16). Heraclitus holds an unconventional theology of logos. The Pythagoreans maintain a religious-mystical practice including the transmigration of souls. The Pre-Socratic period thus contains both the most aggressive ancient critique of traditional religion and one of its most influential mystical traditions, within the same century.

Legacy

The Pre-Socratics shape the categories of all subsequent Western philosophy through Plato (428/427–348/347 BCE) and Aristotle (384–322 BCE), both of whom inherit Pre-Socratic problems as their own. Plato's theory of Forms responds to the Heraclitus–Parmenides dispute by locating being in unchanging Forms and becoming in the world of sensible particulars. Aristotle's account of substance, change, and the four causes in Metaphysics is a systematic engagement with the Milesians, the Eleatics, the pluralists, and the atomists; his summary of his predecessors in Metaphysics A is the source for much of what is known about them.

The Hellenistic schools — Epicureanism, Stoicism, Skepticism — draw heavily on Pre-Socratic resources. Epicurean physics is a development of Democritean atomism; Stoic cosmology builds on Heraclitean logos; Skepticism inherits the Pre-Socratic willingness to question received opinion. The atomist tradition is preserved into Roman antiquity through Lucretius' De Rerum Natura (c. 55 BCE) and revived in the seventeenth century by Pierre Gassendi.

The modern reception begins with Friedrich Schleiermacher's editions and Hegel's history of philosophy (Lectures on the History of Philosophy, delivered 1805–1831), which integrates the Pre-Socratics into the dialectical narrative of Spirit. The decisive nineteenth-century engagement is Friedrich Nietzsche's Philosophy in the Tragic Age of the Greeks (composed 1873, published 1923), which reads the Pre-Socratics as the high point of Greek thought and the original tragedians of philosophy. Martin Heidegger's lectures on the Pre-Socratics, particularly Early Greek Thinking (lectures 1943–1944, published 1950), are the major twentieth-century continental engagement; Heidegger reads Anaximander, Parmenides, and Heraclitus as thinkers of being who were occluded by the Platonic-Aristotelian metaphysics that followed them.

Internal debates within the tradition

The active scholarly debates about the Pre-Socratics divide into four areas.

Reconstruction. Because the texts are fragmentary, any account of what a Pre-Socratic held is also a reconstruction. The standard reconstructions — Parmenides as the founder of strict monism, Heraclitus as the philosopher of flux, the atomists as proto-materialists — have all been challenged. Patricia Curd's The Legacy of Parmenides (1998) argues that Parmenides defends predicational rather than numerical monism; Daniel Graham's Explaining the Cosmos (2006) argues that the Milesians were not, in the standard sense, material monists at all but transformational pluralists; Catherine Osborne's Heraclitus and her general work argue that the standard flux reading of Heraclitus underplays his commitment to underlying measure.

The Eleatic challenge. What exactly did Parmenides argue, and how do later Pre-Socratics respond? The work of Alexander Mourelatos (The Route of Parmenides, 1970), John Palmer (Parmenides and Presocratic Philosophy, 2009), and Curd has reframed Parmenides as a more sophisticated thinker than the strict-monist caricature, with corresponding changes in how the pluralists' responses are read.

The Sophists. Whether the Sophists belong to philosophy proper, and how to read figures such as Protagoras and Gorgias, has been a live debate since Plato. The work of G. B. Kerferd (The Sophistic Movement, 1981), Edward Schiappa (Protagoras and Logos, 1991, second edition 2003), and Rachel Barney has rehabilitated the Sophists as philosophical figures rather than as the rhetorical opponents of Socrates.

Religious and ritual context. Work by Walter Burkert (Lore and Science in Ancient Pythagoreanism, 1972), M. L. West (Early Greek Philosophy and the Orient, 1971), and recent scholarship on the Derveni Papyrus (a fourth-century BCE text discovered in 1962, containing commentary on an Orphic poem) has complicated the standard picture of Pre-Socratic naturalism, showing closer integration with religious and ritual life than the older narrative allowed.

The active journals for Pre-Socratic scholarship include Phronesis, Oxford Studies in Ancient Philosophy, Apeiron, the Journal of the History of Philosophy, and Ancient Philosophy. The Symposium Praesocraticum is the principal recurring international conference. The Cambridge Companion to Early Greek Philosophy (ed. A. A. Long, 1999) and the Oxford Handbook of Presocratic Philosophy (ed. Patricia Curd and Daniel W. Graham, 2008) are the standard reference works.

Texts and transmission

The Pre-Socratics survived because Plato and Aristotle quoted them, because the Hellenistic doxographers summarized them, because Christian apologists from Clement onward used them to argue for the continuity of pagan wisdom with Christian revelation, and because late-antique commentators on Aristotle — especially Simplicius — preserved long stretches of their text to make sense of the Physics and On the Heavens. The Arabic philosophical tradition transmitted some material; the Latin tradition received them largely through Aristotle until the Renaissance recovery of Diogenes Laertius. The modern critical-edition tradition begins with Henri Estienne's 1573 Poesis Philosophica and culminates in Diels–Kranz.

The result is that what is known about the Pre-Socratics is filtered through the agendas of later readers. Aristotle reads them as failed proto-Aristotelians; Plato reads them as preparations for himself; the Stoics read them as proto-Stoics; the doxographers organize them by topic in ways that obscure individual systems. Contemporary scholarship works against this filter, attempting to recover the Pre-Socratics on something closer to their own terms — a project that remains under way.