Parménides

Parmenides of Elea (c. 515–c. 450 BCE) was an early Greek philosopher and a central figure in the Eleatic School. He is best known for the poem On Nature, of which only fragments survive, preserved by later authors. Born in Elea (modern Velia) in Magna Graecia, he is traditionally regarded as the founder of the Eleatic School; his teachings influenced Zeno of Elea and Melissus of Samos, as well as later philosophers such as Plato and Aristotle.

In his poem, Parmenides distinguishes two paths of inquiry: the Way of Truth, which asserts a single, unchanging reality, and the Way of Opinion, which describes the world of appearances. The core claim of the Way of Truth is that "Being is, and non-being is not." From this, he argues that what is must be eternal, indivisible, motionless, and complete; it cannot emerge or perish, and it cannot be void or divisible. Change, plurality, and multiplicity, as perceived by the senses, are illusory. Since non-being cannot exist, there can be no becoming or extinction.

The Way of Opinion presents seemingly empirical, but unreliable, appearances—a world of change and multiplicity. Reason is the route to true knowledge, while the senses mislead.

Parmenides’ thought posed a fundamental challenge to pre-Socratic natural philosophy, influencing later debates about being, contradiction, and the nature of knowledge. His austere metaphysics shaped subsequent ontology and epistemology, notably informing Plato and provoking critiques by Aristotle.