Moses Maimonides (Moses ben Maimon; 1135–1204), a native of Spain, is incontestably the greatest name in Jewish medieval philosophy, but his reputation is not derived from any outstanding originality in philosophical thought. Rather, the distinction of Maimonides, who is also the most eminent codifier of Jewish religious law, is to be found in the vast scope of his attempt, in the Dalālat al-hā’irin (The Guide for the Perplexed), to safeguard both religious law and philosophy (the public communication of which would be destructive of the law) without suppressing the issues between them and without trying to impose, on a theoretical plane, a final, universally binding solution to the conflict.

As Maimonides states in his introduction to the Guide, he regarded his self-imposed task as perilous, and he therefore had recourse to a whole system of precautions designed to conceal his true meaning from people who, lacking the necessary qualifications, might misread the book and abandon observance of the law. Maimonides himself notes that these precautions include deliberately contradictory statements meant to mislead the undiscerning reader. The apparent or real contradictions encountered in the Guide are perhaps most flagrant in Maimonides’ doctrine concerning God. There seems to be no plausible hypothesis capable of explaining away the inconsistencies between the following three views:

1. God has an eternal will that is not bound by natural laws. Through an act of his will, he created the world in time and imposed on it the order of nature. This creation is the greatest of miracles; only if it is admitted can other miracles, which interfere with the causally determined concatenations of events, be regarded as possible. The philosophers’ God, who is not free to cut the wings of a fly, is to be rejected. This conception is in keeping with the traditional religious view of God and is avowedly adopted by Maimonides because failure to do so would undermine religion.

2. Humans are incapable of having any positive knowledge concerning God. No positive attributes—e.g., wisdom or life—can be ascribed to God. Contrary to the attributes predicated of created beings, the divine attributes are strictly negative; they state what God is not. For instance, he is not not-wise, and such a statement is not a positive assertion. Hence, only a negative theology is possible—saying what God is not. The way God acts can, however, be known. This knowledge is to be found in natural science.

3. God is an intellect. The formula used by medieval philosophers—which maintains that in God the knowing subject, the object known, and the act of intellectual knowledge are identical—derives from Aristotle’s thesis that God knows only himself. In adopting the formula, however, Maimonides interpreted it in the light of human psychology and epistemology, pointing out that, according to Aristotle, the act of human (as well as divine) cognition brings about an identity of the cognizing subject and the cognized object. The parallel drawn by Maimonides between the human and the divine intellect quite evidently implies a certain similarity between the two; in other words, it is incompatible with the negative theology of other passages of the Guide. Nor can it be reconciled with his theological doctrine that the structure of the world—created in time—came into being through the action of God’s will.

There would be no enigma in the Guide if Maimonides had believed that truth can be discovered in a suprarational way, through revelations vouchsafed to the Prophets. This, however, is not the case. Maimonides held that the Prophets (with the exception of Moses) combine great intellectual ability, which qualifies them to be philosophers, with a powerful imagination. The intellectual faculty of the philosophers and the prophets receives an overflow from the active intellect. In the case of the Prophets, this overflow not only brings about intellectual activity but also passes over into the imaginative faculty, giving rise to visions and dreams. The fact that prophets have a strong imagination gives them no superiority in knowledge over philosophers, who do not have it. Moses, who belonged to a higher category than did the other Prophets, did not have recourse to imagination.

The laws and religion as instituted by Moses are intended not only to ensure the bodily welfare and safety of the members of the community but also to facilitate the attainment of intellectual truths by individuals gifted enough to uncover the various hints embodied in religious laws and practices. This does not mean that all the beliefs inculcated by Judaism are true. Some indeed express philosophical truths—though in an inaccurate way, in a language suited to the intellectual capacity of the common people, who in general cannot grasp the import of the dogmas they are required to profess. Other beliefs, however, are false but necessary for the preservation of public order and justice—e.g., the belief that God is angry with wrongdoers.

There are two noteworthy aspects of Maimonides’ position on the Law—i.e., the religious commandments. First, he maintained that it is unique in its excellence and valid for all time. This profession of faith, at least with regard to its assumptions about the future, lacked philosophical justification; however, it could be regarded as necessary for the survival of Judaism. Second, he asserted that certain precepts of the Mosaic Law were related to specific historical situations and to the need to avoid too sharp a break with popular customs and practices—for instance, the commandments concerning sacrifice.

For at least four or five centuries, The Guide for the Perplexed exercised a very strong influence in the European centers of Jewish thought; in the 13th century, when the Guide was twice translated into Hebrew, these centers were Spain, the south of France, and Italy. Rather paradoxically, in view of the unsystematic character of Maimonides’ exposition, it was used as a standard textbook of philosophy and condemned as such when the teaching of philosophy came under attack. The Guide could be used in this way because from the 13th century onward the history of Jewish philosophy in European countries acquired a continuity it had never had before. This development seems to have resulted from the substitution of Hebrew for Arabic as the language of philosophical exposition. Because of the existence of a common and relatively homogeneous philosophical background—Hebrew texts were much less numerous and less diverse than Arabic philosophical works—and the fact that Jewish philosophers reading and writing in Hebrew read the works of their contemporaries and immediate predecessors, something like a dialogue can be discerned. In striking contrast to the immediately preceding period, European Jewish philosophers in the 13th century and later frequently devoted a very considerable part of their treatises to discussions of the opinions of other Jewish philosophers. That many of the Jewish philosophers in question wrote commentaries on the Guide undoubtedly furthered this tendency.

Averroists

The influence of Maimonides’ great Islamic contemporary Averroës, many of whose commentaries and treatises were translated into Hebrew, was second only to that of Maimonides on Jewish intellectual development. Indeed, it may be argued that for philosophers (as distinct from the general reading public) it often came first. In certain cases, commentators on the Guide quote Averroës’ opinions in order to clarify those of Maimonides, despite the frequent divergences between the two.

The apparently significant influence of Christian Scholastic thought on Jewish philosophy was often not openly acknowledged by Jewish thinkers in the period beginning with the 13th century. Samuel ibn Tibbon (c. 1150–c. 1230), one of the translators of the Guide into Hebrew and a philosopher in his own right, remarked that the philosophical sciences were more widely known among Christians than among Muslims. Somewhat later, at the end of the 13th century and after, Jewish scholars in Italy translated into Hebrew various texts of St. Thomas Aquinas and other Christian representatives of Scholasticism; not infrequently, some of them acknowledged the debt they owed their Christian masters. In Spain and in the south of France, a different convention seems to have prevailed up to the second half of the 15th century. Whereas Jewish philosophers of these countries felt no reluctance about referring to Greek, Arabic, and other Jewish philosophers, they refrained from citing Christian thinkers whose views had, in all probability, influenced them. In the case of certain Jewish thinkers, this absence of reference to the Christian Scholastics served to disguise the fact that in many essentials they were representative of the philosophical trends, such as Latin Averroism, that were current among the Christian Scholastics of their time.

There is a striking resemblance between certain views of the Latin Averroists and the parallel opinions of Isaac Albalag, a Jewish philosopher who lived in the second half of the 13th century, probably in Catalonia, Spain, and who wrote a commentary in Hebrew on the Tahāfut al-falāsifah (“The Inconsistencies of the Philosophers”), an exposition of Avicenna’s doctrine written by the Muslim philosopher al-Ghazālī (1058–1111). Albalag’s assertion that both the teachings of the Bible and the truths demonstrated by reason must be believed even if they are contradictory raises the possibility that some historical connections exist between this view and the Latin Averroist doctrine that there are two sets of truths—the religious and the philosophical—which are not necessarily in accord. On most other points Albalag was a follower of the system of Averroës himself. This position is exemplified by Albalag’s rejection of the view that the world was created in time. Although he professed to believe in what he called “absolute creation in time,” this expression merely signifies that at any given moment the continued existence of the world depends on God’s existence, an opinion that is essentially in harmony with Averroës.

Joseph Caspi (1297–1340), a prolific philosopher and exegetical commentator, maintained a somewhat unsystematic philosophical position that seems to have been influenced by Averroës. He expressed the opinion that knowledge of the future, including that possessed by God himself, is probabilistic in nature. The prescience of the Prophets is the same. Caspi’s interest in this problem may well have had some connection with the debate about future contingencies in which Christian Scholastics were engaged at that time.

Moses of Narbonne, or Moses Narboni, like many other Jewish scholars of the 14th century, wrote mainly commentaries, including those on biblical books, on treatises of Averroës, and on Maimonides’ Guide. In his commentary on the Guide, Narboni often interprets the earlier philosopher’s opinions by recourse to Averroës’ views. Narboni also expounded and gave radical interpretations to certain conceptions that he understood as implied in the Guide. According to Narboni, God participates in all things, because he is the measure of all substances. God’s existence appears to be bound up with that of the world, to which he has a relation analogous to that between a soul and its body (a comparison already made in the Guide).

Gersonides

Gersonides, also known as Levi ben Gershom (1288–1344), wrote the systematic philosophical work Sefer milḥamot Adonai (“The Book of the Wars of the Lord”), as well as many philosophical commentaries. Gersonides cited Greek, Arabic, and Jewish thinkers, and in many ways his system appears to have stemmed from the doctrines of Maimonides or Averroës, regardless of whether he agreed with them. For example, he explicitly rejected Maimonides’ doctrine of negative theology. Although he never explicitly mentioned Christian Scholastic philosophers, a comparison of his opinions and of the particular problems that engaged his attention with the Scholastic writings of his period suggests that he was influenced by the Latins on certain points.

Gersonides disagreed both with the Aristotelian philosophers who maintained the eternity of the world and with the religious partisans who believed in the creation of the world in time out of nothing. He argued instead that God created the world in time out of a preexistent body that lacked all form. As Gersonides conceived it, this body seems to be similar to primal matter.

The problem of human freedom of action and a particular version of the problem of God’s knowledge of future contingencies form an important part of Gersonides’ doctrine. Unlike the great Jewish and Muslim Aristotelians, Gersonides believed in astrology and held that all happenings in the world except human actions are governed by a strict determinism. God’s knowledge does not extend to individual human acts but embraces the general order of things; it grasps the laws of universal determinism but is incapable of apprehending events resulting from human freedom. Thus, the object of God’s knowledge is a totally determined world order, which differs from the real world insofar as the latter is in some measure formed according to human freedom.

Gersonides does not appear to have assigned to the prophets any political function; according to him, their role consists of predicting future events. The providence exercised by the heavenly bodies ensures the existence in a given political society of people with an aptitude for the handicrafts and professions necessary for the survival of the community. He remarked that in this way the various human activities are distributed in a manner superior to that outlined in the Republic of Plato. Thus, he explicitly rejected Plato’s political philosophy, which, because it was suitable to a society ruled through laws promulgated by a prophet (Muhammad), had been an important element of Jewish philosophy in the Arabic period.