IBN SHEM TOV, ISAAC BEN SHEM TOV (15th century), Spanish rabbi and philosopher. Isaac ben Shem Tov was the son of the anti-Aristotelian mystic, Shem Tov *Ibn Shem Tov, but his intellectual temperament differed severely from his father's. He became a loyal Aristotelian rationalist, more so than his older brother Joseph Shem Tov *Ibn Shem Tov and as much as his nephew Shem-Tov b. Joseph Shem Tov *Ibn Shem Tov. He taught philosophy in Aguilar de Campóo, Castile, and was an erudite and prolific writer in Hebrew on Aristotelian themes, specializing in commentaries on philosophic classics. He wrote at least 14 works, eight of which are extant. These include four commentaries on Averroes' "Intermediate Commentary on Aristotle's Physics" and a favorable commentary on the book singularly decried by his father – Maimonides' Guide of the Perplexed. He was an eager critic of Ḥasdai *Crescas, but generally, the subtleties of Crescas' revolutionary thought on such subjects as actual infinity seem to have eluded him. On the other hand, he may have been the first Hebrew author to distinguish between the categorematic and syncategorematic infinities.
H.A. Wolfson, in: Studies… A.S. Freidus (1929), 279–90; idem, Crescas' Critique of Aristotle (1929), index; S. Rosenberg, He'arot be-Mussag ha-"Einsofiyyut" (1969), 31–2.