physician and historian who was the first Jewish philosopher to draw on Aristotle's writings in a systematic fashion. He is probably more esteemed today for his history Sefer ha-kabbala (“Book of Tradition”) than for his major philosophic work, Sefer ha-emuna ha-rama (“Book of Sublime Faith”), extant only in Hebrew and German translations.

Ibn Daud wrote the former work in answer to an attack on rabbinic authority by the Karaites, a heretical Jewish sect that considered only Scripture as authoritative, not the Jewish Oral Law as embodied in the Talmud, the rabbinic compendium of law, lore, and commentary. Thus, he attempted to demonstrate the unbroken chain of rabbinic tradition from Moses, providing much valuable information about contemporary Spanish Jewry, their synagogues, and their religious practices.

Deriving his Aristotelianism from the 11th-century physician and philosopher Avicenna and other Islāmic writers, Ibn Daud intended the Emuna ha-rama as a solution to the problem of free will. Divided into three sections dealing with physics and metaphysics, religion, and ethics, the Emuna ha-rama was eclipsed by the more precise Aristotelian writings of the 12th-century rabbi Maimonides.