In 1284, Sa’d Ibn Kammuna, an elderly and highly respected Jewish scholar and philosopher, well-versed in astronomy, mathematics, and literature, and a correspondent of Nasir ad-Din at-Tusi and other erudites of the day, was spirited out of Baghdad in a leather-covered box, narrowly escaping the sentence of burning pronounced against him. His offense: a notably dispassionate work published in 1280 that compared Judaism, Christianity, and Islam.

Langermann suggests that the offending book was prompted in part by polemics against Judaism although, as Ibn Kammuna reports, it was stimulated by more civil conversations or debates. Ibn Kammuna’s comparative book was strikingly irenic, describing the three religions without vitriol, outlining their strengths and weaknesses, and stressing the commonalities: Exponents of all three are theists (muhaqqiqun, “upholders of the Truth”) and followers of prophecy; they, like the best philosophers, anchor ethical duties in their theism; and all three faiths (as the Qur’an urges) uphold God’s final judgment.

Ibn Kammuna based his account of Judaism on the work of Halevi and Maimonides as the outstanding philosophical exponents of his own religion. His language is “reverential” toward Jesus, in Langermann’s words, and Ibn Kammuna tactfully cites “what he calls the Christian version of biblical texts"—yet is as pointed as any Jew or Muslim would be about the logic of the Trinity. He knows Islam far better than Christianity, having extensively studied Ghazali and Fakhr ad-Din ar-Razi. Ibn Kammuna is deferential enough to attach the pious blessings of Muhammad that Muslims add to any mention of his name. Yet he resolutely denies any proof of Muhammad’s perfection—or capacity to perfect others. Muhammad did not turn the world from lies to truth. No free and educated person, Ibn Kammuna writes, embraces Islam unless under threat, hoping for a job, infatuated with a Muslim woman, or eager to escape the poll tax imposed only on dhimmis (protected religious minorities who submit to Muslim rule). Ibn Kammuna was testing the freedom he prized under the Ilkhanids’ Mongol successor state based in Iran. But he crossed a line.

Why, then, the four-year delay between his book’s appearance and the mob attack? The scholar, admired for his learning, was under the protection of the powerful Juwayni family, which included the governor of Isfahan. He held high administrative responsibilities, helping to restore the governance and economy of Baghdad after the devastating Mongol conquest. The value placed on his services by the regime is attested by his title, Izz ad-Dawla (Glory of the State) and his abiding Jewish loyalty by the omission of wa-l-Din (and the Faith). But in 1284, a senior Juwayni and several of his sons were executed. Suddenly Ibn Kammuna’s outrageous posture became known. He escaped to Hilla where his son held office, but Ibn Kammuna died soon after.

The book now translated by Langermann is not that comparative study but a conspectus of Ibn Kammuna’s more typical contributions as a philosopher: He saw profound affinities between Judaism and the illuminism of Suhrawardi, crucified for heresy at age 36 on Saladin’s orders at Aleppo in 1191. Illuminism, a Sufi-oriented synthesis of philosophy and scriptural monotheism, was built on the rational mysticism of Avicenna. Ibn Kammuna was one of the two major commentators on Suhrawardi, probably the first. But later illuminists (ishraqis), though reliant on his work, assiduously erased his name even when quoting him verbatim, lest they acknowledge learning from a Jew.

Ibn Kammuna longed for proof of personal immortality, “obsessed” as Langermann puts it, “with the soul’s endless perdurance.” Arguments on the issue pervade his oeuvre, which Langermann, an able guide, has read in widely. Ibn Kammuna’s focus on immortality led him, like Avicenna, to vest human individuality not in the body, which will dissolve in time, but in our self-awareness.[1] Still, he disagreed with Avicenna’s view that immortal souls begin with our corporeal origins, holding instead with Plato that rational souls are eternal. He drew “bold” parallels, Langermann writes, between our self-awareness and God’s self-knowledge, resting his case for immortality on a “perhaps daring” analogy between the soul’s simplicity and the absolute simplicity of God. Given God’s absolute simplicity, Ibn Kammuna reasoned that the same self-knowledge must be the source of God’s creativity.

A keen analyst as well as a synthetic thinker, Ibn Kammuna saw a flaw in Avicenna’s arguments for monotheism: It was not enough to prove that the “necessary being” was unique. A being might be alone in its genus but not unique. To caulk the chink, Ibn Kammuna appealed to Aristotle’s argument that there is but one world. For, as Maimonides had argued, seeing the world as one “is critical or very helpful in proving God one.”[2]

The “liar paradox” (exemplified in constructions such as “This sentence is false,” which is true if it is false but false if it is true), an ancient and enduring fascination of philosophers, was of special interest to Ibn Kammuna, who, like today’s philosophers, sought ways of resolving the tangle of such paradoxes. But the successors who erased his pioneering work on Suhrawardi dismissed those efforts, calling the liar and other paradoxes sophisms (shubah). Here, they kept Ibn Kammuna’s name.

Ibn Kammuna’s ecumenical spirit is prominent in the book at hand. Citing a Qur’anic verse with key parallels in both the Hebrew Bible and the New Testament, “He is the First and the Last, the Apparent and the Hidden,” Ibn Kammuna glosses “First and Last” by reference to God’s timelessness. “Apparent and Hidden,” Langermann writes, “if I understand correctly, convey the visible or apparent products of the hidden god.”

Moshe Perlmann edited and translated Ibn Kammuna’s trail-blazing comparative work on religious ideas in 1967 and 1971.[3] Reza Pourjavady and Sabine Schmidke published a rich sampling of Arabic texts from his other writings in 2006 along with an impressive introduction that traces what is known of his life and works, his links to other thinkers, and his impact and reception.[4] The work Langermann translates now—also with a generous and learned introduction, synopses, and commentary—is among the texts edited in that volume.

Langermann’s contextual learning opens up to us the subtext of Ibn Kammuna’s pleas to Baha ad-Din, the new power at Isfahan, noted for his cruelty, urging that there is more strength in clemency than in harshness, and his “forceful and original” warning in behalf of ahl al-dhimma, Jews and Christians, that experience teaches that harm to these protected communities will destabilize a monarchy.

Langermann, an Arabic professor at Bar-Ilan University, is a doyen of Arabists, much in the tradition of earlier greats such as Hellmut Ritter, Agha Buzurg, Carl Brockelmann, David Baneth, Leon Nemoy, and others. His translation, though not for beginners, is a valuable resource for scholars wishing to follow along as a master of our generation reads and parses the words of an astute philosopher, one whose life and work detractors failed to blot out or efface.

[1] See Lenn E. Goodman, Avicenna (Ithaca: Cornell University Press, 2006), pp. 149-73.

[2] Maimonides, Guide to the Perplexed, quoted here from the forthcoming translation/commentary by Lenn E. Goodman and Phillip Lieberman, 1.100b; cf. 2.9b-10b. Page references are to Salomon Munk, Le guide des égarés (Paris: Osnabrück, 1964, 1856-66 repr.).

[3] Ibn Kammuna’s Examination of the Three Faiths: A Thirteenth Century Essay in Comparative Religion, Moshe Perlmann, ed. (Berkeley: University of California Press, 1967); Ibn Kammuna’s Examination of the Three Faiths: A Thirteenth Century Essay in Comparative Study of Religion, Moshe Perlmann, trans. (Berkeley: University of California Press, 1971).

[4] Reza Pourjavady and Sabine Schmidke, A Jewish Philosopher of Baghdad: ‘Izz al-Dawla Ibn Kammuna (d. 683/1284) and his Writings (Leiden: Brill, 2006).