A Critical Edition of Al-Jili's Treatise on the Forth Figure Al-Lame fi al-Shakl al-Rabe

For the first time in the history of logic, Abd al Razzaq Al-Jili (d. 570/1174), in the treatise Al-Lame fi al-Shakl al-Rabe, dealt with the modal syllogisms of the fourth figure. Previous to him, Dinha, the priest, and Ibn Salah Al-hamadani had discussed the non-modal moods of the fourth figure. Jili’s treatise deals only with simple modalities and ignores the complex ones. His pupil, Fakhr al-Din Al-Razi, like his master, neglected the complex moods of the figure, but denied Al-Jili’s modalities for three moods. Al-Razi’s pupil, Zayn al-Din Al-Kashshi, developed the complex moods of the fourth figure. After Afzal al-Din Al-Khunaji realized that negative particulars have conversions in some complex modalities, Athir al-Din Al-Abhari discovered three new valid moods in the modal fourth figure.