On Truth - Classic Text | Alexandria
On Truth (Περὶ Ἀληθείας) by Protagoras stands as one of the most influential yet enigmatic texts of ancient Greek philosophy, known primarily through fragmentary references and philosophical discourse. This seminal work, composed around 440 BCE by the sophist Protagoras of Abdera, introduced the revolutionary concept that "man is the measure of all things" (homo-mensura), challenging traditional absolutist notions of truth and reality.
First mentioned in Plato's Theaetetus and later referenced by Sextus Empiricus, the text emerged during the intellectual ferment of Classical Athens, when sophisticated philosophical debates about the nature of knowledge and reality flourished alongside democratic innovations. This period witnessed intense philosophical competition between emerging sophistic relativism and traditional metaphysical approaches to truth, making On Truth a flashpoint in ancient philosophical discourse.
The work's impact reverberated through antiquity, influencing epistemological debates and spawning centuries of philosophical commentary. While the complete text has been lost, surviving fragments suggest a sophisticated argument for perspectival truth, asserting that individual perception determines reality—a stance that presaged modern philosophical relativism and constructivist theories of knowledge. Scholars continue to debate whether Protagoras advocated for a radical subjective relativism or a more nuanced form of perspectivism, with interpretations ranging from epistemological skepticism to proto-pragmatism.
The legacy of On Truth extends far beyond its historical context, informing contemporary discussions in philosophy of science, cognitive psychology, and political theory. Its central thesis about the relationship between human perception and truth remains startlingly relevant in our era of competing truth claims and epistemological uncertainty. Modern thinkers continue to grapple with Protagoras's challenging question: If truth is indeed relative to human perception, how do we navigate between individual perspective and collective understanding? The work's enduring influence demonstrates how ancient philosophical insights can illuminate current debates about truth, knowledge, and the human condition.