Philosophical commentator of the fifteenth century; younger brother of Joseph ibn Shem-?ob, and a follower of Maimonides. Isaac sided with his brother against their father, Shem-?ob ibn Shem-?ob, 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-?ob who wrote, at Aguilar do Campo in 1459, a commentary on Ghazali's "Metaphysics" (Paris MS. No. 906).