athir al-din abhari’s “al-risalat al-zahirah”: an edition, commentary and analysis with a discussion of the manuscripts

athir al-din abhari is one of the most outstanding logicians of the islamic period, even though he is less known to contemporary scholars than other logicians. this article, by presenting an edition of al-risalat al-zahirah (the shining treatise), not only makes available for the first time in print an important text in the field of logic, but also surveys some of abhari's logical thought with an analysis of the text from the perspective of modern logic. the important issues which this article presents are: 1. that abhari believes that transitivity of implication does not result in connective-conditionals. he mentions and then criticizes the exact proof which is now used to prove this rule; 2. that abhari was aware of the conditional proof; 3. that abhari challenged the conditional contraposition; 4. that abhari, like relative logicians, considers entailment implication to be valid, whereas his opponents, like the stoics and the followers of frege-russellean logic apply material implication. al-risalat al-zahirah has been edited using a selective methodology on the basis of the manuscripts of tehran university, the iranian islamic congress library, and the ayatullah marashi' library.