Philosophical commentator of the fifteenth century; younger brother of Joseph ibn Shem-Ṭob, and a follower of Maimonides. Isaac sided with his brother against their father, Shem-Ṭob ibn Shem-Ṭob, who, in his "Sefer ha-Emunot," had attacked Maimonides. Isaac's commentary on Maimonides' "Moreh" is known only through a quotation by Moses Alashkar ("Hassagot," p. 6, ed. Ferrara, 1556). According to Steinschneider, he is probably identical with the Isaac ibn Shem-Ṭob who wrote, at Aguilar do Campo in 1459, a commentary on Ghazali's "Metaphysics" (Paris MS. No. 906).