Preconception

A preconception is the general idea of a thing that forms naturally in the mind after we meet it again and again — so that hearing "horse" or "human," we already know what is meant before any argument begins. Epicurus made these built-up notions a criterion of truth, a clear standard against which we test our opinions and even confirm that the gods exist. The Stoics likewise treated such common notions, arising untaught in everyone, as the shared starting point of all inquiry. Without them, Epicurus argued, we could neither name things, nor search for them, nor judge whether what we say is true.