Stoicism, a school of thought that flourished in Greek and Roman antiquity. It was one of the loftiest and most sublime philosophies in the record of Western civilization. In urging participation in human affairs, Stoics have always believed that the goal of all inquiry is to provide a mode of conduct characterized by tranquillity of mind and certainty of moral worth.

The Stoics believed that perception is the basis of true knowledge. In logic, their comprehensive presentation of the topic is derived from perception, yielding not only the judgment that knowledge is possible but also that certainty is possible, on the analogy of the incorrigibility of perceptua...