To date, scholars have skilfully discussed aspects of Polqar’s thought, and yet none of the existing studies offers a comprehensive examination that covers Polqar’s thought in its entirety. This book aims to fill this lacuna by tracing and contextualizing both Polqar’s Islamic sources (al-Fārābī, Avicenna, and Averroes) and his Jewish sources (Maimonides and Isaac Albalag). The study brings to light three of Polqar’s main purposes; (1) seeking to defend Judaism as a true religion against Christianity; (2) similarly to his fellow Jewish Averroists, Polqar wishes to defend the discipline of philosophy. By philosophy, Polqar means Averroes' interpretation of Aristotle. As a consequence, he offers an Averroistic interpretation of Judaism and becomes one of the main representatives of Jewish Averroism; (3) defending his philosophical interpretation of Judaism. From a social and political point of view, Polqar's unreserved embrace of philosophy raised problems within the Jewish community; he had to refute the Jewish traditionalists’ charge that he was a heretic, led astray by philosophy. The main objective guiding this study is that Polqar advances a systematic naturalistic interpretation of Judaism, which in many cases does not agree with traditional Jewish views. "Haliva’s lucid, learned, and incisive monograph on the thought of Isaac Polqar is the first comprehensive study devoted to this important, but neglected fourteenth century Jewish Averroist. It makes a significant contribution to our knowledge of post-Maimonidean medieval Jewish philosophy. Haliva convincingly shows that while Polqar claims to follow Maimonides, he consistently pushes his thought in a more radical direction, offering a severely naturalistic interpretation of Jewish religious principles and refusing to make any concessions to more traditional theological modes of thought. Her study leads us to ask whether it is possible to uphold such an uncompromising philosophical and naturalistic reading of Judaism as that of Polqar, that is, whether it does justice to the Jewish religious principles it purports to interpret and enables us to maintain the authority of traditional Halakhah." Lawrence J. Kaplan, McGill University, Montreal "Racheli Haliva's excellent book is the first comprehensive study of the philosophy of Isaac Polqar (late thirteenth-early fourteenth century). Polqar emerges as a radical and creative thinker–a fascinating link between the philosophy of Averroes and Maimonides and that of Spinoza." Warren Zev Harvey, Hebrew University of Jerusalem "Haliva's groundbreaking book is the first comprehensive study of Polqar's intellectual world, forged in the crucible of the late Middle Ages where Greco-Arabic philosophy and the Maimonidean legacy meet inner-Jewish and anti-Christian polemics. Polqar, Haliva demonstrates, was a formidable thinker in his own right who critically engages with Maimonides and Averroes. At the same time, he defends the Jewish faith as the only true religion of reason--against Kabbalists and Jewish traditionalists and against his former teacher, Abner of Burgos, whose conversion to Christianity was a major intellectual shock. This is a meticulously researched and lucidly argued scholarly contribution that fills a crucial gap in the history of Jewish philosophy." Carlos Fraenkel, McGill University, Montreal