Skepsis

Skepsis, from the Greek skepsis meaning examination, doubt, or inquiry, refers to a broad set of philosophical positions that question the possibility of certain knowledge or the justification of beliefs. In philosophy, skepticism examines the reliability of our cognitive faculties, the sources of our beliefs, and the methods by which knowledge is supposed to be established.

In antiquity, Skepsis described a skeptical attitude and several schools. Pyrrhonian skepticism, founded by Pyrrho of Elis, emphasizes epoché, or suspension of judgment, with the aim of achieving tranquility (ataraxia) by not affirming or denying any non-evident propositions. Academic skepticism, linked with the Old and Middle Academy (notably Arcesilaus and Carneades), held that certainty is unattainable and that beliefs should be assessed by reason and virtue, often appealing to probability rather than certainty.

Core ideas include withholding assent to non-evident claims and, in some strands, refraining from dogmatic commitment while still engaging in inquiry. For Pyrrhonists, peace of mind arises from avoiding philosophical controversies; for Academic skeptics, skeptical reasoning underpins a cautious approach to beliefs and arguments.

Skepticism has influenced subsequent philosophical traditions, shaping debates in epistemology, the philosophy of science, and religious and political thought. It appears in varying forms from Cartesian and Humean critiques of knowledge to contemporary discussions about justification, probability, and the limits of human understanding. The term continues to denote both methodological skepticism—using doubt as a tool to test claims—and a more widespread epistemic caution about what can be known. See also Pyrrho, Pyrrhonism, Academic Skepticism, Epistemology, Skepticism (philosophy).