Anaximenes of Miletus

Born some time around 586 BC. Died some time around 526 BC (age ~60).

Axaximenes was a friend & successor of Anaximander. His life outside of philosophy remains unknown.

Anaximenes accepted the assertion that the world is ultimately composed of a single element. Like Thales, but unlike Anaximander, he asserted that this element is determinate. However, unlike Thales, Anaximenes asserted that the prime element is air. Furthermore, Anaximenes postulated a method by which one element could transform into another. He proposed a theory of condensation/rarefaction: when air is condensed, it becomes colder, eventually becoming water and then earth; when air expands, it heats up, eventually becoming fire. Famously, he demonstrated this by showing that exhaling with a wide open mouth produced warm air, whereas exhaling with pursed lips produced cold air.

Anaximenes had a reputation for attempting to explain natural phenomenon without reference to religion or myth. For example, he was the first recorded Greek to propose a natural explanation for rainbows.

Anaximenes’ contribution to philosophy is his attempt to refine the theories of his predecessors using scientific evidence.

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