The Plausible

To pithanon — 'the convincing' or 'the plausible,' rendered in Latin as probabile — was the practical test devised by Carneades, head of the skeptical Academy in the 2nd c. BCE. Since no impression can be certified as true, Carneades argued, you can still rank impressions by how convincing they are and act on the most convincing, checking it against related impressions to make it more reliable still. This let the Academic skeptics meet the objection that doubt makes action impossible. Through Cicero's Latin 'probabile,' the idea seeded the long Western tradition of probabilism and reasoning under uncertainty.