propositional logic
In the Hellenistic period
(323-31 B.C.)
, and apparently
independent of Aristotle's achievements, the logicians
Diodorus Cronus and his pupil Philo worked out the
beginnings of a logic that took propositions, rather than
terms, as its basic elements. They infl uenced the second
major theorist of logic in antiquity, the Stoic Chrysippus
(mid-3rd c.), whose main achievement is the
development of a propositional logic, crowned by a
deductive system