In the great libraries of Europe and the United States, hidden in fading manuscripts on forgotten shelves, lie the works of medieval Hebrew logic. From the end of the twelfth century through the Renaissance, Jews wrote and translated commentaries and original compositions in Aristotelian logic. One can say without exaggeration that wherever Jews studied philosophy - Spain, France, Northern Africa, Germany, Palestine - they began their studies with logic. Yet with few exceptions, the manuscripts that were catalogued in the last century have failed to arouse the interest of modem scholars. While the history of logic is now an established sub-discipline of the history of philosophy, the history of Hebrew logic is only in its infancy. The present work contains a translation and commentary of what is arguably the greatest work of Hebrew logic, the Sefer ha-Heqqesh ha-Yashar (The Book of the Correct Syllogism) of Levi ben Gershom (Gersonides; 1288-1344). Gersonides is well known today as a philosopher, astronomer, mathematician, and biblical exegete. But in the Middle Ages he was also famous for his prowess as a logician. The Correct Syllogism is his attempt to construct a theory of the syllogism that is free of what he considers to be the 'mistakes' of Aristotle, as interpreted by the Moslem commentator A verroes. It is an absorbing, challenging work, first written by Gersonides when he was merely thirty-one years old, then significantly revised by him. The translation presented here is of the revised version.

One On the Types of Sentences.- Two On Retracted Sentences.- Three On the Relative Extensions of Modally Qualified Terms.- Four On Consequences by Virtue of the Part and the Whole.- Five On Consequences by Virtue of Subalternation and Obversion.- Six On Consequences by Virtue of the Placement and Removal of Relational Particles and Prepositions.- Seven On Consequences by Virtue of the Placement and Removal of Modes.- Eight On Consequences by Virtue of the Conversion of Sentences.- Nine On the Modality of Consequences by Virtue of the Conversion of Sentences.- Ten On the Extension of Terms in Sentences.- One on the Conditions of the Syllogism.- Two on the Relationship between the Premises and the Conclusion of the Syllogism.- Three on the First Figure.- Four on the Second Figure.- Five on the Third Figure.- Six on the Fourth Figure.- Seven on Sorites.- Eight on the Conditions of Syllogisms with Modes, Particles, and Retracted Terms.- Nine on Syllogisms with Necessary Premises.- Ten on Syllogisms with Assertoric Premises.- Eleven on Syllogisms with Possible Premises.- Twelve on Syllogisms Mixed from Necessary and Assertoric Premises.- Thirteen on Syllogisms Mixed from Necessary and Possible Premises.- Fourteen on Syllogisms Mixed from Assertoric and Possible Premises.- Commentary.- Excursus Aristotle's Modal Syllogistic and Averroes' Theory of Modalized Terms.- Works Cited In Commentary And Excursus.- Hebrew-EngLish Glossary.- English-HeBrew Glossary.- Selected BIbliography.