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Alcmaeon of Croton (c. 540–500 BCE)

(c. 540500 BCE)

Alcmaeon of Croton (a Greek city-state in southern Italy) was a pioneer in the study of human psychology and physiology. He published one book in the late sixth or first half of the fifth century BCE. Only two or three fragments of the book survive, but substantial reports of his views are preserved in authors such as Theophrastus. It is controversial whether Alcmaeon was primarily a physician and medical writer or whether he dealt with physiological issues as part of a typical pre-Socratic account of the cosmos. Beginning in the second century CE, some authors call him a Pythagorean, but the earliest sources do not. Aristotle appears to distinguish him from the Pythagoreans (Metaph. 986a22).

Alcmaeon is the earliest author to state the common ancient view that health depends on a balance of opposed powers in the body. Just as Anaximander used a political analogy to explain the workings of the cosmos, Alcmaeon said that "equality (isonomia ) of powers (wet, dry, cold, hot, bitter, sweet, etc.) maintains health, but monarchy among them produces disease" (Fr. 4 Diels-Kranz). Alcmaeon may have excised an eyeball and observed passages (poroi i.e., the optic nerve) leading from the eye toward the brain. Perhaps as a result of this observation, he was the first person in the Greek tradition to argue that the brain was the seat of thought. There is no evidence, however, that he used dissection to any further extent or that he practiced it systematically. He was the first to address a series of issues that would become standard in later writings on physiology, such as the causes of sleep, waking, and death. He argued that human seed came from the brain, that the brain was the first part of the embryo to develop and that both parents contributed seed in the production of children.

In contrast to the wealth of evidence for Alcmaeon's views on human physiology, the evidence for his cosmological views is sketchy. He may have believed that the cosmos, like the human body, arose from a balance of opposing powers. He also maintained that the sun was flat.

Alcmaeon argued that there was no human knowledge of what is not perceptible and that judgments about what is not perceptible can only be made on the basis of what is perceived. He was the first to make a clear distinction between animals, which only have sense perception, and human beings, who also have understanding. Alcmaeon may have originated the three-step empiricist epistemology found in both Plato (Phaedo 96ab) and Aristotle (Posterior Analytics 100a3) that begins with sensations, which when collected become memories and opinions, which in turn become knowledge when they gain fixity. Finally, Alcmaeon gave the first argument for the immortality of the soul. The exact nature of Alcmaeon's argument is hard to reconstruct, because it was later developed by Plato in the Phaedrus (245c), but he appears to have argued that the soul was immortal because it was in constant motion.

See also Anaximander; Aristotle; Plato; Psychology; Pythagoras and Pythagoreanism; Theophrastus.


texts and commentaries

Diels, H., and W. Kranz. Die Fragmente der Vorsokratiker. 6th ed., vol. 1, 210216. Dublin, Ireland: Weidmann, 1952. Contains the Greek texts with translations in German.

Wachtler, J. De Alcmaeone Crotoniata. Leipzig, Germany: Teubner, 1896. Contains Greek texts with commentary in Latin.


Lloyd, G. E. R. "Alcmeon and the Early History of Dissection." Sudhoffs Archiv 59 (1975): 113147.

Mansfeld, J. "Alcmaeon: 'Physikos' or Physician." In Kephalaion: Studies in Greek Philosophy and its continuation offered to Professor C. J. de Vogel, edited by J. Mansfeld and L. M. de Rijk, 2638. Assen, Netherlands: Van Gorcum, 1975.

Vlastos, Gregory. "Isonomia." American Journal of Philology 74 (4) (1953): 337366.

Carl Huffman (2005)

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Alcmaeon (ălkmē´ən), in Greek legend, son of Amphiaraüs and Eriphyle, a leader of the expedition of the Epigoni against Thebes. He murdered his mother in revenge for his father's death and consequently was haunted by the Erinyes until he found haven on Achelous' island. There he married Callirrhoë, daughter of Achelous, and lived in peace until his wife demanded the sacred robe and necklace of Harmonia, which were in the possession of his former wife Arsinoë. When he tried to regain them from Arsinoë, her brothers killed him.

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