Anaximenes of Miletus (c. 585 – c. 525 BCE) was an early Greek philosopher of the Milesian school, traditionally regarded as a successor to Thales and Anaximander. He is known for proposing air (Greek: ἀήρ, aēr) as the fundamental principle (arche) underlying all natural phenomena.
Biography
Anaximenes was born in Miletus, an Ionian city on the western coast of Anatolia (modern Turkey). Ancient sources describe him as a contemporary and possibly a student of Anaximander, although the precise nature of their relationship remains uncertain. Like many pre‑Socratic thinkers, biographical details are scarce; most information about his life is derived from later authors such as Aristotle, Theophrastus, and Simplicius.
Philosophical Doctrine
- Air as the Primary Substance: Anaximenes posited that air is the originating substance of the cosmos. He argued that through processes of condensation (thickening) and rarefaction (thinning), air transforms into the variety of material forms observed in the world, giving rise to fire, wind, cloud, water, earth, and stone.
- Cosmology: He suggested that the Earth is a flat, floating disc suspended in the air, supported by its own weight. The Sun, Moon, and planets were thought to be formed from thickened air and to revolve around the Earth.
- Natural Explanation of Phenomena: Anaximenes sought natural explanations for atmospheric and meteorological events, attributing winds, clouds, rain, and thunder to the movements and transformations of air.
Works and Fragments
No complete works by Anaximenes survive. Knowledge of his thought comes primarily from fragmentary quotations and summaries in the works of later philosophers and commentators. The most substantial fragments are preserved in Aristotle’s Physics and Metaphysics, as well as in the *Commentary on the Categories by Simplicius.
Influence and Legacy
Anaximenes’ identification of a single material principle contributed to the development of monistic natural philosophy in ancient Greece. His ideas influenced subsequent pre‑Socratic thinkers, notably Heraclitus, and were referenced by later philosophers debating the nature of the primary substance. The concept of transformation through condensation and rarefaction anticipated later scientific notions of phase changes, although it remained within a qualitative framework.
Historical Assessment
Modern scholarship regards Anaximenes as a pivotal figure in the transition from mythic explanations of the world to rational, naturalistic speculation. His work exemplifies the Milesian attempt to account for the diversity of the natural world through a single underlying element, a theme that recurs throughout the history of philosophical thought.