The Beginnings

Logic as a discipline starts with the transition from the customary use of certain logical methods and argument patterns to the reflection on and inquiry into these and their elements, including the syntax and semantics of sentences. In antiquity, logic as a systematic discipline begins with Aristotle. However, discussions of some elements of logic and a focus on methods of inference can be traced back to the late fifth century BCE.

Syntax and Semantics

Some of the Sophists classified types of sentences (logoi) according to their force. So Protagoras (485–415), who included wish, question, answer, and command (Diels-Kranz 80.A1, Diogenes Laertius 9.53–4), and Alcidamas (pupil of Gorgias, fl. fourth century BCE), who distinguished assertion (phasis), denial (apophasis), question, and appellation (Diogenes Laertius 9.54). Antisthenes (mid-5th–mid-4th cent.) defined a sentence as "that which indicates what a thing was or is" (Diogenes Laertius 6.3, Diels-Kranz 45) and stated...