In the two centuries following Saadia and Israeli, Jewish thought was largely under the influence of Mu'tazilite kalam and Neoplatonism. This is especially the case in Islamic Spain, where Israeli inspired a long line of Jewish Neoplatonists. In the twelfth century, however, kalam and Neoplatonism gave way to Aristotelianism, which would come to dominate Jewish philosophical discussion about the soul for the remainder of the Middle Ages.
The most important and influential of the Jewish Aristotelians was Moses Maimonides, legal scholar, communal leader, physician, and philosopher in Egypt. To be sure, Maimonides does not fit neatly into any school tradition of Aristotelianism, nor did he write systematically on the soul (or any other philosophical subject). Yet his nonsystematic eclectic discourses and his enigmatic judgments did much to stimulate Jewish thought for several centuries to come. A brief description of his most fruitful discussions of the soul will be given here.
Maimonides’ early commentary on the Mishnah, like all his writings, was novel in many ways. It is comprehensive, providing explanation of all Mishnaic tractates, including those without Talmudic explication; and it includes three systematic prefaces, two of which relate to the soul. As introduction to tractate Avot, a collection of Tannaitic wisdom sayings, Maimonides provides a synthetic primer in Aristotelian ethics, which would become the standard textbook in philosophical ethics used by Jews throughout the later Middle Ages. In the first few chapters, as introduction to the doctrine of the mean, he presents a brief discourse on the soul and its faculties. Borrowing from al-Farabl’s Select Aphorisms (sometimes word-for-word), he defends the unity of the soul, the uniqueness of the human soul (which is essentially different than animal and plant souls), and describes the soul’s faculties and their functions: nutrition, sensation, appetite, imagination, and reason - both practical and theoretical. By knowing the soul the physician of the soul, that is, the ethicist, can diagnose, treat, and cure the soul’s sicknesses, leading it from extreme behavior to the mean and from a life of vice to a life of virtue. Yet the question remains: how does one determine what the mean is? Here Maimonides diverges from al-FarabI (and Aristotle), identifying knowledge of God as the orienting ethical principle toward which all actions should lead.
The other introduction relating to psychic matters prefaces an earlier chapter of the Mishnah, Chapter. 10 (‘‘Heleq’’) of Sanhedrin. Working off the qualified first sentence of this chapter - all Jews have a share (heleq) in the world to come, except... - Maimonides presents a survey of different conceptions of the ‘‘world to come.’’ He counts five: the garden of Eden and Gehinnom construed as places of corporeal pleasure or pain; the messianic age, governed by an eternal king who rules an elite population of immortal giants; the time of resurrection, when all deserving souls are reconstituted with their bodies and live forever in peace; a this-worldly ‘‘world to come,’’ characterized by universal health, wealth, peace, and security; the final view, according to Maimonides, combines all the others: a messianic age, when the dead are resurrected, experience infinite pleasure in the garden of Eden, and live forever in peace and security. Following a brief excursus on education and exegesis, in which the primarily rhetorical and heuristic character of any doctrine of reward is exposed, he presents his own purely spiritualistic view: that knowledge of God is the highest goal and contemplation of God the greatest reward; this alone is true delight; it has no share whatsoever in anything material.
Maimonides’ ethics and eschatology are repeated in his comprehensive code of law, the Mishneh Torah. In the ''Laws of Ethical Dispositions’’ Maimonides presents a complete ethical theory - in Jewish legal context - governed by the principles of Aristotle’s doctrine of the mean (although there is constant tension between ethical moderation and intellectual extremism). In the ''Laws of Repentance’’ the spiritualistic intellectualistic orientation of the Introduction to Heleq is reproduced in striking form: true love of God results from knowledge of God (''according to the knowledge, will be the love’’), as exemplified by the single-minded passion of the lover in Song of Songs, who seeks conjunction with her beloved active intellect, or the rabbinic ideal in Berakhot. ''In the world to come, there is no eating, drinking, or sexual relations, but rather the righteous sit with their crowns on their heads enjoying the radiance of the divine presence.’’
The Guide of the Perplexed - Maimonides’ philosophical-theological magnum opus - also includes significant material about the soul and intellect, although generally it is difficult to determine what his true opinion might have been on any particular subject. The text itself is framed by the noetic nature of man - created in the (intellectual) image of God (Guide 1:1), and directed toward intellectual perfection as his final end (Guide 3:54) - and has discussions of soul and intellect throughout. For example, in Guide 1:72 and 2:6-7 Maimonides presents a fairly standard Neoplatonized-Aristotelian emanationist cosmology, with the active intellect - the last of the celestial intelligences - construed as the cause of existence and final aim of knowledge. In Guide 1:40-42 he lists various definitions - philosophical and nonphilosophical alike - of the equivocal terms ''soul,’’ ''spirit,’’ ''life,’’ and ''death.’’ And in Guide 1:68 he presents a summary of the Aristotelian doctrine of the identity of knower and thing known. Many of the traditional theological doctrines in the Guide are understood with the help of the theory of the active intellect. Both prophecy and providence are explained as resulting from a divine overflow through the active intellect to individuals with properly prepared intellects.
There are other chapters in the Guide, however, which complicate matters, suggesting that cognition, for Mai-monides, is far more difficult than it might first appear. In contemporary Maimonidean scholarship these chapters have led to a series of studies and counter-studies, arguing that Maimonides, who seems to place such great emphasis on intellectual perfection, conjunction, and knowledge of God, in fact believed that these designated goals could not possibly be achieved by any human being (except, perhaps, by Moses). Based on remarks about the limitations of the human intellect - incapable of apprehending even the celestial world, let alone God - recent scholars have suggested that Maimonides was a metaphysical critic (akin to Kant) or even a skeptic.
In Maimonides’ own time, in contrast, he was accused of exactly the opposite: being far too enamored with the intellectual life. Based mainly on his commentary on the Mishnah and Mishneh Torah, he was charged with denying the religious doctrine of resurrection, and of promoting a purely elitist noetic doctrine of eternal reward, based solely on intellectual accomplishment. In response to these accusations, he wrote his ''Letter on Resurrection,’’ an apologetic tract, which might be considered his last philosophical-theological writing. Resurrection, he writes there, is rabbinic dogma, and he accepts it, just as others should; he does not deny it or explain it metaphorically. On the contrary, precisely because it is dogma and cannot be proved rationally it should simply be accepted on faith; and moreover denying it affects belief in other related subjects, such as miracles. Nevertheless, he reaffirms what he stated in earlier works: that the final reward, beyond any other reward, the ''world to come’’ where one reaches true life without death, is incorporeal - made up of ''souls without bodies, like angels.’’