Parmenides (early fifth century B.C.), Greek philosopher, the most influential of the pre- Socratics, active in Elea (Roman and modern Velia), an Ionian Greek colony in southern Italy. He was the first Greek thinker who can properly be called an ontologist or metaphysician. Plato refers to him as ‘venerable and awesome,’ as ‘having magnificent depth’ (Theaetetus 183e– 184a), and presents him in the dialogue Parmenides as a searching critic – in a fictional and dialectical transposition – of Plato’s own theory of Forms. Nearly 150 lines of a didactic poem by Parmenides have been preserved, assembled into about twenty fragments. The first part, ‘Truth,’ provides the earliest specimen in Greek intellectual history of a sustained deductive argument. Drawing on intuitions concerning thinking, knowing, and language, Parmenides argues that ‘the real’ or ‘what-is’ or ‘being’ (to eon) must be ungenerable and imperishable, indivisible, and unchanging. According to a Plato-inspired tradition, Parmenides held that ‘all is one.’ But the phrase does not occur in the fragments; Parmenides does not even speak of ‘the One’; and it is possible that either a holistic One or a plurality of absolute monads might conform to Parmenides’ deduction. Nonetheless, it is difficult to resist the impression that the argument converges on a unique entity, which may indifferently be referred to as Being, or the All, or the One.
Parmenides embraces fully the paradoxical consequence that the world of ordinary experience fails to qualify as ‘what-is.’ Nonetheless, in ‘Opinions,’ the second part of the poem, he expounds a dualist cosmology. It is unclear whether this is intended as candid phenomenology – a doctrine of appearances – or as an ironic foil to ‘Truth.’ It is noteworthy that Parmenides was probably a physician by profession. Ancient reports to this effect are borne out by fragments (from ‘Opinions’) with embryological themes, as well as by archaeological findings at Velia that link the memory of Parmenides with Romanperiod remains of a medical school at that site. Parmenides’ own attitude notwithstanding, ‘Opinions’ recorded four major scientific breakthroughs, some of which, doubtless, were Parmenides’ own discoveries: that the earth is a sphere; that the two tropics and the Arctic and Antarctic circles divide the earth into five zones; that the moon gets its light from the sun; and that the morning star and the evening star are the same planet.
The term Eleatic School is misleading when it is used to suggest a common doctrine supposedly held by Parmenides, Zeno of Elea, Melissus of Samos, and (anticipating Parmenides) Xenophanes of Colophon. The fact is, many philosophical groups and movements, from the middle of the fifth century onward, were influenced, in different ways, by Parmenides, including the ‘pluralists,’ Empedocles, Anaxagoras, and Democritus. Parmenides’ deductions, transformed by Zeno into a repertoire of full-blown paradoxes, provided the model both for the eristic of the Sophists and for Socrates’ elenchus. Moreover, the Parmenidean criteria for ‘whatis’ lie unmistakably in the background not only of Plato’s theory of Forms but also of salient features of Aristotle’s system, notably, the priority of actuality over potentiality, the unmoved mover, and the man-begets-man principle. Indeed, all philosophical and scientific systems that posit principles of conservation (of substance, of matter, of matter-energy) are inalienably the heirs to Parmenides’ deduction.
See also ELEATIC SCHOOL, MELISSUS OF SAMOS , PRE -SOCRATIC. A.P.D.M.