Aside from overcoming the Fallacy of Four Terms, what were the major contributions of Stoic syllogisms? What did they provide that Aristotelian syllogisms could not? And, what were their major limitations?
One of the limitations of the Stoics is that they did not "grasp as clearly as Aristotle the formal nature of invalidity." Ian Mueller pointed this out in a famous article on Stoic Logic. His argument was that they merely provided a framework to settle inferential validity and reveal those questions that fall outside logic (such as soundness questions related to metaphysics implied by the premises).