Ḥasdai Crescas and Simeon ben Ẓemah Duran on Tradition versus Rational Inquiry

Seth (Avi) Kadish
Oranim Academic College of Education and University of Haifa


Ḥasdai Crescas (c. 1340-1410/11) and Simeon ben Ẓemah Duran (1361-1444) were products of the same culture and reflect a shared intellectual tradition. Persecution of the Jews in Spain that peaked in 1391 led the former to devote the rest of his life to rebuilding Spanish Jewish communities, while the latter fled Spain and became an influential rabbinic leader in Algiers.

As time went on, the intellectual gap between them became much wider than the sea between them. Duran had a passion for the details both in his Torah study and in his analysis of the shared general knowledge of the Middle Ages; he combined them without hesitation in his voluminous encyclopedic writings, which reflect their common understanding in his time. Crescas was Duran’s intellectual opposite: He focused on underlying concepts and principles in a consistent way, and refrained from combining unlike things in his concise writings. He attempted to expose the conceptual basis of tradition and of philosophy, demanding that each be allowed to speak on its own terms, and eschewed the idea that each provides support for the other. He tried to think anew about common assumptions on both sides for every issue he confronted.

Crescas and Duran provide an example of how different personalities and intellectual bents can lead to vastly different outlooks, even for two people who share common intellectual roots and similar concerns. Elements of the debate between them still inform contemporary discussions of Torah and science.

Ḥasdai Crescas and Simeon ben Zemah Duran

Ḥasdai Crescas (c. 1340-1410/11) is best known for his critique of medieval Aristotelianism.[1] That was his outstanding intellectual achievement, and it made him one of just a handful of thinkers in his era who helped to pave the way for modern science. Scholars have also appreciated his theology and considered its connection to Crescas’s rabbinic leadership in Spain during troubled times. Unlike his philosophy, which was a negative critique, in his theology Crescas builds something new.[2] Both are aspects of a single, concise book entitled Or Adonai (“The Light of the Lord”), and Crescas’s motivation for pursuing them both was the same—namely, to help meet the challenges he faced in rebuilding Jewish communities in Spain, which had been ravaged by violent persecution in the year 1391 (and in which his only son was martyred). Crescas felt that Maimonideanism had weakened the resolve of Jews in Spain to remain loyal to God and the Torah when faced with mortal threats. His response was to undermine the perceived certainty of the Aristotelian axioms, which lay at the heart of Maimonidean Judaism, and to offer his people a different kind of theology in its place.[3]

A further theme that runs through the entirety of Or Adonai is a persistent demand for intellectual modesty and integrity. The book, like so much of religious philosophy in the Middle Ages, is ultimately designed to deal with the clash between tradition and the results of rational inquiry. But unlike a great many other works in the field, it carefully avoids subjugating one realm to the other. Crescas refuses to judge the veracity of tradition or radically reinterpret it in light of rational inquiry, and he equally refuses to subjugate rational inquiry to the strictures of tradition. He insists instead that each realm must be studied on its own terms. Furthermore, Crescas avoids extending the truth-claims of either realm to encompass areas where they do not legitimately apply. This consistent attitude lies at the heart of his negative critique of Aristotelianism and his positive theology alike.

Crescas’s underlying approach becomes sharply defined when we compare his work to that of his younger colleague, Simeon ben Ẓemah Duran (1361-1444), who wrote a parallel book entitled Magen Avot (“Shield of the Patriarchs”).[4] Both men were products of the same culture and educated in a shared intellectual tradition: Crescas was a student of Nissim Gerondi (1315/20-1376), while Duran was a student of Gerondi’s students. Both of them received the same Spanish rabbinic education and served their communities as first class talmudic scholars and halakhic decisors. They achieved similar mastery of the very same corpus of medieval philosophy (mostly in Hebrew translation), including the works of great Jewish philosophers such as Maimonides and Gersonides (for whom they shared an attitude of esteem mixed with unease). Both men were proficient in a wide range of fields. Their ways parted in 1391 when Duran fled Spain. He soon became an influential rabbinic leader in Algiers, and he left a major halakhic legacy: his responsa eventually became an authoritative source for Rabbi Joseph Karo.[5] Crescas remained in Spain, where he devoted the rest of his life to rebuilding the Jewish communities that were devastated in 1391.

As time went on, however, the intellectual gap between these two men became far wider than the sea that separated them. It is true that their areas of intellectual interest and the problems that troubled them remained extremely similar throughout their respective lives. They even chose to write books in the very same genre, namely “books of principles” in which the structure of each book as well as its contents are determined by a system of dogma.[6] Yet at the same time, their fundamental approaches to the problem of tradition versus rational inquiry became diametrically opposed. Their opposite intellectual tendencies find expression not just in their formal positions, but even in their writing styles and senses of organization. A comparison will show that although these two men were products of the very same culture and faced similar tensions and challenges, their individual intellectual temperaments took them in opposite directions.

Towards the end of his life, Duran read Crescas’s Or Adonai. His shock at what he read led to a flurry of literary activity in the form of refutations.[7] Even though these anti-Crescas works by Duran are long lost, we may surmise that it was the minimalistic attitude at the core of Or Adonai that so deeply offended him. Duran accepted the Aristotelian view of nature as largely true, and argued that it is simultaneously confirmed by logic, experience and the Torah. There can be little doubt that Duran must have been deeply troubled when he read Crescas’s sharp anti-Aristotelian arguments, which attack that world-view at its core and argue that little or none of it can be confirmed by logic, experience, or the Torah.

Yet Crescas’s intellectual modesty may have troubled Duran no less than his anti-Aristotelian position. The attitude that underlies Crescas’s formal arguments is that logic, experience, and the Torah can each only convey limited aspects of reality. Therefore, they don’t often touch upon one another, and they rarely confirm each other. The best one can usually do is to show that they don’t contradict one another. This kind of modesty was foreign not just to medieval Aristotelianism, but even to the kind of traditionalism represented by Duran.

As we shall see, echoes of their principled disagreements and of their highly different underlying attitudes can still be heard in contemporary discussions of religion and science, or in Jewish discussions of the tension between the yeshivah and the academy. A better understanding of Crescas, which can be sharpened through a comparison to Duran, can help to enrich that discussion.

Writing Style and Structure

For a reader, the contrast in style between Crescas’s Or Adonai and Duran’s Magen Avot is immediately striking: neither book is easy to read and digest, but for opposite reasons. The writing in Or Adonai is exceedingly brief, to the point that Crescas’s writing is often hard to understand. Even a reader familiar with his style is likely to find that she needs to read a paragraph several times in order to make sense of it. The style of Magen Avot, in contrast, is exceedingly verbose. Its language is not difficult, and so the reader can easily get a sense of what the author is trying to say as she reads the book line-by-line. But as she continues to read on at length, and as she encounters numerous examples and questions and proofs accompanied by lengthy, unexpected tangents—tangents so huge that they often dwarf the declared topic of a given chapter—she is likely to lose track of the issue at hand, or of the book as a whole.

This vivid difference between their writing styles is complemented by the formal structures of their two respective “books of principles.” In one sense they are similar: neither book’s structure is based upon a clear, intuitive dogmatic structure that might serve future generations as an effective pedagogic tool. Both Or Adonai and Magen Avot were written as responses to Maimonides’s list of thirteen foundations of the Torah, the former as a replacement for Maimonides’s system and the latter as an adaptation which attempts to improve upon it. But unlike the list of thirteen principles, neither Crescas’s replacement nor Duran’s adaptation can be used as a simple pedagogic tool. To understand why, a general description is in order.

Crescas’s system fails as a pedagogic tool because, instead of a straightforward list, he built it on four different levels. He divided Or Adonai into four formal treatises, each one devoted to a different class of principles. Furthermore, the distinctions between these four classes are somewhat subtle and even ambiguous. My understanding of the book’s structure is briefly as follows:[8]

  1. The first treatise of Or Adonai is devoted to showing that rational inquiry cannot prove the existence of the Aristotelian God, the unmoved mover. The Aristotelian God is, for Crescas, incompatible with the God of the Bible and the sages of Israel because it lacks will, is not a personality, and is incapable of a relationship. Crescas’s nuanced, relentless, and devastating critique of medieval Aristotelian science is motivated by his need to show that there is no compelling, logical reason to accept the God of Aristotle. Thus, the major thrust of this treatise is negative. And yet, at the end, Crescas opens the door to the possibility of a very different concept of God, one that to his mind is compatible with tradition. Once rational inquiry has been shown to confirm little if anything about God, Crescas compares its meagre results to the limited yet significant things that the tradition does firmly claim about the nature of God. He finds that there is no contradiction between the two.
  2. The second treatise of Or Adonai is about God’s gift of the Torah to Israel. That gift is evidence of a relationship, and Crescas has already shown in the first treatise that there is no compelling reason to think that God is incapable of a relationship. Now, Crescas further argues that if there is to be is any meaningful relationship between God and human beings, then each of them must possess three mutual capabilities: they must both be capable of cognition of each other; they must both possess personal volition; and they must both be capable of meaningful action upon one another. The Torah itself is a testament to all three of these mutual capabilities. Given the regnant philosophical outlook in his time, the most striking of these major themes in the second treatise are specifically Crescas’s position that God knows individual human beings, has a will regarding them, and that both God and man can act meaningfully upon one another. His defense of tradition is thus to demonstrate that rational inquiry does not contradict these “cornerstones” which make the Torah conceivable. In his order of presentation, Crescas was the opposite of his predecessor Gersonides and his younger contemporary Duran (who in this matter walked in Gersonides’s footsteps). Gersonides and Duran both took pains to present the full scientific corpus first for each issue, and then compare it to the Torah second. But for Crescas, the Torah comes first: once the God of tradition has been rendered possible (first treatise), Crescas can focus primarily on what God has revealed in the rest of the book.
  3. The third treatise examines the Torah’s general claims about the nature of reality, which include creation, immortality of the soul, reward and punishment, resurrection, the eternally binding nature of the Torah, the prophecy of Moses, the effectiveness of the Urim ve-Tummim, and the messiah. It shows yet again that rational inquiry does not contradict these claims. A second part of this treatise does the same for the Torah’s assertions regarding the effectiveness of certain commandments—namely, prayer and the priestly blessing, repentance, and the Day of Atonement along with other special seasons of the year. It is possible to conceive of a significant relationship between God and human beings that lacks any or all of these principles (second treatise), yet God, when he gave his gift of the Torah to Israel, declared them all to be true (third treatise). Beyond its individual themes, what is most striking about the third treatise as a whole is how little it claims about the concrete nature of reality in the here and now (compared to both Maimonides and Duran). It also asserts very little about the nature of the Torah. This is especially true when one takes into account the leeway that Crescas grants for how the Torah’s assertions may be understood.
  4. The fourth and final treatise of Or Adonai might seem to be no more than an appendix, and yet it is perhaps the most intriguing part of the book, as it reveals aspects of Crescas’s underlying motivations. In it we find a list of thirteen aspects of reality about which the Torah makes no absolute claims.[9] This is not to say that Crescas is agnostic concerning what the Torah says about these things; on the contrary, he has a firm opinion regarding most of them and takes pains (as in previous treatises) to show that rational inquiry does not contradict his opinion. And yet, all thirteen of these topics were the subjects of heated debate by Jewish scholars in the Middle Ages. By placing them in the fourth treatise, Crescas indicates that all sides of the debate remain within the tradition.

In short, the four-part structure of Or Adonai is simultaneously original, fascinating, challenging, and revealing. But it is also subtle and complicated, and as such it cannot serve as the basis for a popular creed or catechism.

Unlike Crescas’s Or Adonai, Duran directly follows Maimonides’s list of thirteen foundations of the Torah in his book Magen Avot. He further divides them into three basic groups: God, Torah, and Recompense. He then devotes a single chapter to each foundation, for a total of thirteen chapters in three parts. This initially seems like a clear and useful structure, but then Duran confounds it by adding “pillars” upon which Maimonides’s thirteen foundations of the Torah stand, along with “derivative principles” to which the bulk of his book is devoted. We will explore these further below. In the meantime it is sufficient to say that in their parallel attempts to move discussion of Maimonides’s dogma forward, neither Crescas nor Duran offered a popular alternative to his list of thirteen foundations, which might serve future generations well as a catechism.

They similarly failed to achieve the organizational simplicity of Sefer ha-`Ikkarim by Joseph Albo (a student of Crescas), which is divided into four major parts corresponding to a general discussion of “principles” and three basic dogmas that are identical to Duran’s three groups: God, Torah, and Recompense. The relative popularity of Albo’s work (compared to Or Adonai and Magen Avot) is a consequence of both its simple organization and its clear writing style.[10]

Nevertheless, although the four tiers of Crescas’ dogmatic system did not (and apparently could not) achieve the popularity Maimonides’s thirteen principles, or even that of Albo’s Sefer ha-`Ikkarim, they still have one clear advantage over the organization of Duran’s Magen Avot: in Or Adonai, each chapter has a clear focus on its formal topic. Although the overall organization of the book was not a pedagogical success, and its brevity is not always conducive to reading, its chapters are nevertheless precise implementations of their declared intentions. The same thing cannot be said of Duran’s Magen Avot: although its formal structure is quite clear and even appealing at first glance, the author grossly violates that structure in the actual content of the book’s chapters. While its first five chapters (part one of the book about God) are actually devoted to the first five of Maimonides’s thirteen foundations, most of the rest do nothing of the sort. Instead, as we shall see below, they serve the author as opportunities to present his reader with treatises on vast areas of medieval science. Nothing like that exists in Or Adonai.

We now examine a few examples in order to illustrate the differences between the two books. The overall comparison will show that their complicated styles and organization are not bugs, but were rather intended as features. Furthermore, it will become clear that the way each of these two books was written is an expression of its author’s intellectual temperament and the principled way he chose to deal with the confrontation between tradition and rational inquiry.

The Barnacle Goose, the Tree-Woman and Duran’s Jewish Encyclopedia

We begin with an entertaining example of the counter-intuitive structure and content of Duran’s Magen Avot and how it differs radically from Or Adonai. It appears within an essay on the nutritive and reproductive faculties of living beings, which are shared by vegetation, animals, and humans alike. In a biological tangent dealing with rabbinic views on reproduction, he mentions the following tidbit:[11]

It is to be found that a tree can generate an animal, such as the tree in France in which a bird grows by its beak, and when it is removed [from the tree] it flies. The [Christian] nobles eat it on those days when they fast from meat, because it is not considered meat by them, but our sages say they are forbidden as unclean fowl. And in India there is a tree from which grows the form of a woman who hangs [from the tree] by her hairs. When she is fully grown she falls [from the tree] with a terrible shriek and she dies. Her carcass is more putrid than all other carcasses.[12]

This engaging passage continues with a detailed survey of other connections between the world of plants and the world of animals, interwoven with numerous biblical and rabbinic parallels and prooftexts.

The barnacle goose and the tree-woman appear yet again much later in Magen Avot. Both appearances are in the thirteenth and final chapter of the book, a single chapter that comprises two-thirds of the entire length of the book. These lopsided proportions derive from the fact that the bulk of the book’s final chapter is not directly devoted to Maimonides’s thirteenth principle on the resurrection of the dead. Instead, we find that Duran devotes nearly all of it to two huge topics:

(1) The Soul. This section roughly parallels the faculties of the soul as discussed in Aristotle’s De Anima and medieval works that derive from it, but it further fleshes them out with an enormous amount of information culled from medieval Aristotelian (and pseudo-Aristotelian) works that deal with botany, biology, anatomy and zoology. Although the declared purpose of this voluminous section is to prove the immortality of the human soul, without which there cannot be resurrection, it mostly serves as a medieval Jewish encyclopedia of the natural world.[13]

(2) The Creation of the World. According to Duran, creation implies that God is a volitional being who acts within the world not just via nature, but who, as the creator of nature, may also act in ways that contravene it. Creation itself is the ultimate miracle and, therefore, a “derivative principle” of the resurrection of the dead. If God is volitional and he created nature in an act of volition, then he may resurrect the dead as well. But if nature is eternal, then the dead cannot be resurrected.[14]

It is the first of these two topics that concerns us here. Duran’s habit is to present a vast amount of information about one area of the life sciences after another, mostly drawn from medieval philosophical works, and then conclude his discussion of each topic with rabbinic sources that touch upon it. The latter usually confirm the bulk of data in the former, but sometimes they correct aspects of it as well. According to Duran, the sages of Israel were superior scientists by virtue of the Torah, which encompasses every sort of wisdom. It is only due to the ravages of exile that the Jews are forced to consult gentile wisdom.

Duran returns to the barnacle goose and the tree-woman some 33 dense folios later—a third of the length of the entire book, and yet still well within the “first topic” of its thirteenth and final chapter!—in a separate context. There, he takes pains to show that inanimate objects, plants, animals, and humans are not four completely separate domains: “We have now clarified that the world as a whole is like a single being, and each small part of it derives from yet another part.”[15] In other words, life is a spectrum: In nature we find creatures which fill the gap between inanimate and plant (e.g. coral), between plant and animal (e.g. the barnacle goose and the tree-woman), and between animal and human (e.g. the ape). Duran dwells at length upon the spectrum of life and describes numerous other examples of its essential continuity.

The amusing example of the barnacle goose and the tree-woman is just one of many hundreds of similar curiosities to be found within the numerous tangents in Magen Avot. But when we turn to Crescas’s Or Adonai, we find that such curiosities and tangents are not typical of the book in any way. It is not just that Crescas’s writing is better-organized than Duran’s, and that he was laser-focused on exposing underlying concepts rather than explaining the practical details of nature. It is also that, for Duran, both tradition and rational inquiry make solid claims about the nature of reality in all of its variety and detail, and those claims can and should be compared in all of their aspects. Crescas, as we shall see, does not share this view.

It is tempting to suggest that curiosities like the barnacle-goose and the tree-woman are absent in Crescas’s book simply because he was a less credulous person than Duran. Although this is possible, there is no evidence to back it up. There is nothing in Crescas’s thought per se which suggests he would be likely to deny commonly accepted observations of medieval zoology. On the contrary, Crescas respected the right of rational inquiry to establish whatever it can within its own legitimate realm. It would thus be more prudent to say that for Crescas, detailed observations of animals and plants were simply irrelevant to the goal of his book.

The Garden of Eden and the Structure of Or Adonai

The variety of living things is not the only continuous spectrum to be found in medieval conceptions of nature. Another one is climatology, which had a direct ramification for the medieval understanding of the Garden of Eden. The plain sense of the biblical text indicates that Eden is a geographical location on earth (Genesis 2:8-15). In his introduction to the chapter Ḥeleq within his Commentary of the Mishnah (Sanhedrin chapter 10)—the very same essay which concludes with the thirteen foundations of the Torah—Maimonides explained the Garden of Eden as follows:[16]

The Garden of Eden is a fertile place containing the choicest of the earth’s resources, numerous rivers, and fruit-bearing trees. God will disclose it to man some day. He will teach man the way to it, and men will be happy there. It is possible that many exceedingly wonderful plants will be found there, plants which are far pleasanter and sweeter than those which we now know. None of this is impossible or improbable. On the contrary, paradise would be possible even if it were not written of in the Torah. How much more sure then is it since the Torah specifically promises it!

That the Garden of Eden is a location on earth is neither impossible nor improbable for Maimonides because climate, too, is a full spectrum: we know that there are places on earth which are completely uninhabitable for human beings, and others which are better for habitation to one degree or another. Habitability is a spectrum. It stands to reason, then, that there is also a place on earth at the far end of the spectrum which has the perfect balance for human habitation. That place is Eden, which is therefore natural, not miraculous. Happily, claimed Maimonides, both rational inquiry and the Torah agree that this is so.

Later in his life, Maimonides turned again to the Garden of Eden in two separate chapters of his Guide of the Perplexed.[17] Those chapters may be understood to indicate a different position than his earlier one by suggesting that Eden is a metaphor rather than a geographical location on the earth.[18] However, we find that Nissim Gerondi and his students, including Crescas and Duran, all favored Maimonides’s early position that the Garden of Eden is an actual physical place.[19] There is no doubt that they were fully aware of how Maimonides dealt with Eden in the Guide, and that his words could be taken to deny the reality of Eden on earth. Nevertheless, they adopted a position akin to the one he suggested earlier in the passage cited above.

This unanimity, if properly probed, may reveal more than just a shared conservative impulse. A comparison of Crescas’s Or Adonai to Duran’s Magen Avot shows that they discuss Eden in quite different contexts within their two respective books. We begin with Duran, who mentions Eden matter-of-factly in his introduction to Magen Avot. There he describes Adam, Abraham, and Moses as archetypes for three different kinds of people in terms of their acquisition of wisdom.[20] The first, Adam, enjoyed every possible advantage because of his physical perfection as the direct creation of God and his location in Eden, the best of all places “in the middle of the world.” Had he taken advantage of his situation in Eden to apply himself to study, he would have reached intellectual perfection, but instead he occupied himself with Eden’s worldly pleasures. Due to Adam’s lack of effort, he achieved terrestrial knowledge alone, but he failed to attain knowledge of that which is above the firmament.

Abraham, for Duran, was the opposite of Adam: he suffered from every possible disadvantage in his quest for intellectual enlightenment, and confronted tremendous obstacles in his path. Yet, because of his dedication and perseverance over the course of many long decades, he attained the truth through intellectual inquiry and was further blessed to have that truth confirmed through God’s revelation. Abraham fell prey to no distractions in the form of worldly pleasures, and as a result, he surpassed Adam by apprehending both terrestrial wisdom and knowledge of the heavens to the highest degree of which a human being is capable. The wisdom he acquired also encompassed the commandments of the Torah that would later be given to his descendants. Abraham further strove to disseminate what he learned to humanity.

Moses is Duran’s third archetype: through prophecy, God granted him all that Abraham had attained, but immediately and with ease, in order to deliver it to Israel. Not just Moses himself, but Israel as well is thus blessed with vast knowledge of the cosmos, which each generation inherits through tradition. Therefore, the Jews do not depend on rational inquiry. And yet, since God blessed humanity with intellect, it is right to reconfirm the truth of prophecy via rational inquiry, much as Abraham did.

In Magen Avot, Duran strives to walk in the path of Abraham, namely “to show that what we learn from the Torah is the same as what the gentile philosophers fairly conclude after labor and exertion.” Furthermore, since prophecy is ultimately more reliable than rational inquiry, the latter must be corrected by the former whenever there is a real contradiction between them. We engage in this labor even though we don’t enjoy the privilege of Eden, because Abraham has shown us that it can be done nonetheless.

Both the Garden of Eden and Abraham’s career are themes within Crescas’s Or Adonai as well. Regarding the latter, Crescas invokes Abraham in the closing passage of his first treatise, but he describes him in a very different way than Duran: for Crescas, Abraham found that rational inquiry was incapable of resolving questions about God, and so he remained uncertain until God revealed himself through speech. In other words, prophecy or a tradition based upon it are the only ways to apprehend the divine. The medieval proofs of God’s existence are barren.

A similar thing is true of the Garden of Eden. As opposed to Duran who mentions it in passing (while discussing Adam), and considers its reality on earth to be self-evident, for Crescas the topic occupies a dedicated place within the very structure of his book: the ninth chapter in his fourth treatise is entitled “On the Garden of Eden and Gehinnom,” and Crescas thus considers that topic to be one of the thirteen aspects of reality about which the Torah makes no absolute claims. To be clear: Crescas himself—like Nissim Gerondi, Duran, and many others—thought that Eden is a physical place on earth (although there may also be a higher, “heavenly” Eden as well). That is what he thinks the tradition means, and he argues that rational inquiry does not contradict it. And yet the topic’s very inclusion in the fourth treatise means that, at least in principle, the tradition can bear an alternative understanding of Eden. In other words, even if an allegorical interpretation of Eden is wrong in Crescas’s opinion, it is still not denial of the Torah.

In theory, the fourth treatise of Or Adonai might have included hundreds or thousands of topics, not just thirteen. After all, there are countless places in which the biblical and rabbinic traditions touch upon reality in its myriad details. But in practice, Crescas only selected central topics that were the subject of heated rabbinic debate in his time—such as the geographical existence of Eden on the earth—precisely because these were seen as acute examples of the tension between medieval science and the Jewish tradition. Crescas eased that tension by showing that neither the Torah nor science assert nearly as much as is often claimed in their names. It is likely that he intended to convey irony even in the very number: instead of Maimonides’s thirteen dogmas, Crescas concludes his philosophical work with a list of thirteen uncertainties! In all of this, Crescas was the exact opposite of Duran.

Angels, Demons and the Structure of Magen Avot

Along with Eden, angels and demons are also topics in the fourth and final treatise of Crescas’s Or Adonai.[21] He deals with them in the same principled way that he deals with Eden. But the same thing cannot be said of Duran, who, like Crescas, was aware of them as points of acute tension between the Torah and medieval rationalism. Duran was deeply troubled by the Maimonidean understanding of the nature of angels and its denial of the very existence of demons.[22]His struggle with this topic is expressed in the very structure of the second part of Magen Avot.

Duran designated Part II of Magen Avot as a discussion of prophecy, and he divided it into four chapters corresponding to Maimonides’s sixth through ninth principles: (6) general prophecy, (7) the prophecy of Moses, (8) Torah from heaven, and (9) the eternally binding nature of the commandments. These topics are indeed the formal titles of their respective chapters, yet the main body of each and every chapter contains something else entirely.[23]

Chapter 1 is stated to be about “Prophecy in General” (Maimonides’ sixth principle), but nearly the entire chapter is about terrestrial physics: the four elements and the four levels of their compounds (inanimate, plant, animal, human). This essay is well-written, and it serves the reader as an excellent introduction to that important scientific topic. But it is not about prophecy.

Chapter 2 moves on from physics to metaphysics. Its formal title is “The Prophecy of Moses” (Maimonides’s seventh principle), yet it is actually devoted to a metaphysical discussion of the formation of the earth and the spheres during creation. It also contains a huge preliminary discussion of angels in the Jewish tradition (as understood and explained at great length by Duran).

Chapter 3 is entitled “Torah from Heaven” (Maimonides’s eighth principle), yet it instead continues the lengthy essay on angels, this time with a critical exploration of metaphysics and an essay on the world of demons as well. It also deals with the divine vision of Isaiah and the “chariot” of Ezekiel, and it concludes with polemics aimed at various groups. The main point of the chapter is that there are vast realms “above” Aristotelian metaphysics: Duran insists that since rational inquiry fails through terrestrial physics to apprehend all that exists below, all the more so does it fail to apprehend the vast realms that are above. In the end, Duran briefly ties these vast essays back into prophecy as the topic of Magen Avot Part II: all of this cosmology is ultimately meant to delineate the essence of the voice that Israel heard at Sinai.

Chapter 4 about “The Torah’s Eternity” (Maimonides’s ninth principle) is actually a full-fledged anti-Christological and anti-Islamic polemical treatise.[24]

I have argued elsewhere that the stark dichotomy between the chapter titles and their actual contents in this part of Magen Avot is a result of Duran’s attempt to improve upon Maimonides’s formulation of the thirteen principles, and at the very same time to use Maimondean admissions about the limits of human cognition as blanket permission to depart from his Aristotelianism while still claiming to walk in his footsteps.[25] In his formulation of the sixth and seventh foundations of the Torah, Maimonides stated that the mechanism for prophecy and its very content consists of rational knowledge, but then he declared that he would simply state his principles of prophecy rather than engage in a full exposition of the sciences. Furthermore, in the Guide, Maimonides explicitly says that human intellects cannot grasp the nature of the heavens, and Duran alludes to that statement. It seems that Duran decided to engage in the very exposition of the sciences that Maimonides declined to do, and to do so from a perspective that would improve and expand upon the Aristotelian framework in non-Aristotelian ways. In essence, what Duran does in the second part of Magen Avot is to supply his reader with a “Jewish” treatise on physics and metaphysics, one which he claims is far superior to the standard Aristotelian fare.

All of this is in stark contrast to Crescas. Duran claims that rational inquiry can establish an enormous amount about the terrestrial world, and also a not insignificant amount about the heavens. Its conclusions are not without fault and error, however, and since it is ultimately the work of human beings, there are limits to what it can touch upon. Science therefore needs to be corrected and vastly supplemented via the wisdom of the tradition, which is itself the greatest treasure trove of knowledge about the very nature of the cosmos. The inconsistency that is inherent in this kind of eclecticism is the opposite of Crescas’s principled critical thought. For Crescas, rational inquiry and tradition make more limited claims, each within its own respective realm. Their points of contact and possible tension are thus few and far between compared to what we find in Duran’s Magen Avot.

Contemporary Echoes of Crescas and Duran

When we listen to contemporary discussions of science and religion, we are bound to hear echoes of Crescas and Duran. The latter is represented by a corpus of apologetic literature that attempts to cast doubt upon certain results of modern science, or else to mitigate conflict by reinterpreting pre-modern traditions in the light of modern science. Among certain traditionalist Jews, this approach is partly represented by a small industry devoted to producing “kosher” books and educational materials on topics such as nature, history, psychology and more. Projects like these often present a wealth of valuable material to their readers even as they make selective use of their sources, and as such they are reminiscent of Duran.[26] Furthermore, the creators of some works that deal with Torah and science are accomplished experts in their scientific fields, and at times they achieve their results in creative and ingenious ways that betray an impressive mastery of a wealth of literature, both traditional and modern. This may not mitigate their essential inconsistency, but it can help to make their writing and ideas appealing, impressive and sometimes persuasive. That too is reminiscent of Duran.[27]

Echoes of Crescas’ approach can be heard today as well, and they become quite audible when we think of modern academia as a contemporary parallel to cosmopolitan medieval philosophy (in terms of the challenge that it poses to tradition). As examples of such echoes, it is worth mentioning two traditional scholars, both of whom served as popular public spokesmen for the Jewish tradition and both of whom were very recently deceased over the course of the year 2020. The first one is the late Rabbi Adin Steinzaltz. Yeshiva University in New York granted him an honorary doctorate in 1991, and on that occasion he gave a public lecture about “Torah and Science” (which is also the university’s motto).[28] At the beginning of his lecture, Steinzaltz remarked that when people find themselves confronted by conflicts between Torah and science, those problems are usually rooted in “popular Torah” or “popular science” or both. The more serious and broadminded a scholar is, the less likely he is to find substance in many or most of these apparent conflicts. But at the very same time, Steinzaltz admitted, there will always remain more nuanced, deeper problems that elude resolution. For those questions, the answer is not censorship but honesty, along with the kind of intellectual humility capable of acknowledging that “no one ever died from a question.” That Torah and science are popularly thought to establish far more than they actually do is reminiscent of Crescas, as is a lack of discomfort with the idea that many things can never be known.

Another echo of Crescas can be found in the writing of the late Rabbi Dr. Jonathan Sacks. In The Great Partnership: God, Science and the Search for Meaning, he recalled his personal introduction to the study of philosophy at Oxford in the 1960s:[29]

‘Thank God for the atheists!’ was my first response to philosophy. I was the first member of my family to go to university, and it hit me like a cold shower. Those were the days—Oxford and Cambridge in the 1960s—when the words ‘religion’ and ‘philosophy’ went together like cricket and thunderstorms. You often found them together but the latter generally put an end to the former. Philosophers were atheists, or at least agnostics. That, then, was the default option, and at the time I did not know of any exceptions.

The first thing we did, a kind of nursery-slope exercise, was to refute all the classic proofs for the existence of God…For me, far from being a threat, this was like an immersion in a mikveh, a ritual bath. I felt purified.

All these arguments, by then deemed to be fallacious, were in any case wholly alien to the religion I knew and loved. They were Greek, not Hebraic. They carried with them the scent of Athens, not Jerusalem. They were beautiful but misconceived. As Judah Halevi put it in the eleventh century, they were about the God of Aristotle, not the God of Abraham. Now, every thinking Jew—none more than Maimonides—loves Aristotle, and every feeling Jew loves Socrates, who comes across the pages of history exactly like a rabbi, always asking unsettling questions. Socrates is that most Jewish of figures, an irrepressible iconoclast. But Greece is Greece, Jerusalem is Jerusalem, and the two are not the same.

Slightly earlier in the same book, after summarizing numerous ways in which modern science and philosophy are commonly thought to have had a major subversive impact upon religious belief, Sacks writes:[30]

We think of these as shaking the religious worldview of the Bible, but it was something else entirely. For it was the Greeks who saw the earth as the center of the celestial spheres. It was Aristotle who saw purposes as causes. It was Cicero who formulated the argument from design. It was the Athenian philosophers who believed that there are philosophical proofs for the existence of God…

The Hebrew Bible never thought in these terms…Most of the Bible is about another face of God, the one turned to us in love… This aspect of God is found in relationships, in the face of the human other that carries the face of the divine Other. We should look for the divine presence in compassion, generosity, kindness, understanding, forgiveness, the opening of soul to soul. We create space for God by feeding the hungry, healing the sick, housing the homeless and fighting for justice. God lives in the right hemisphere of the brain, in empathy and interpersonal understanding, in relationships etched with the charisma of grace, not subject and object, command and control, dominance and submission.

Faith is a relationship in which we become God’s partners in the work of love. The phrase sounds absurd. How can an omniscient, omnipotent God need a partner? There is, surely, nothing he cannot do on his own. But this is a left-brain question. The right-brain answer is that there is one thing God cannot do on his own, namely have a relationship. God on his own cannot live within the human heart.

These remarks by Sacks are illuminating because they vividly convey the essential spirit of Crescas’s thought along with the vast differences between his era and our own.

That God is known through relationship (“right-brain”) rather than analysis (“left-brain”)—i.e. that God is a personality, not a concept—is the essential theme of Crescas’s Or Adonai. That the classic proofs of the existence of God can be refuted, and that they are not just impotent but also irrelevant, is the point of the book’s first treatise and its revolutionary critique of medieval Aristotelianism. But one thing that has vividly changed since Crescas’s time is that such refutations have become “a kind of nursery-slope exercise” for us today. Their revolutionary sting was lost centuries ago, and now they are commonplace. Furthemore, to live with God in a personal relationship is an experience that has largely dropped out of individual and public consciousness in the Western world, while at the very same time religion came to be seen as a set of concepts (“left-brain”) to be accepted or rejected. That is why, at first glance, it seems counterintuitive to a great many people today that a refutation of the proofs for God’s existence could serve as part of a heroic effort to bolster Jewish loyalty to the Torah during a time of fierce persecution (Crescas) or to help a traditional Jew today feel “purified” in his faith (Sacks).

Another thing that has changed is Crescas’s alternative to Aristotle. For Crescas, God is known in a “right-brain” way, either through direct personal contact and communication—i.e. prophecy, which is the “light of the Lord”—or else through a thriving tradition of such prophecy that lives among the people who received it. It is no accident that Crecas began Or Adonai by citing Isaiah: “House of Jacob, come and let us walk in the light of the Lord!” (2:5). For the Jews of Spain in Crescas’s time, this was still a powerful and appealing alternative to cosmopolitan philosophy. But Sacks wrote for a very different audience. For the Jews among his readers, there is no longer any assurance that they still think of themselves as members of the “House of Jacob.” Nor is there, for many or most of his readers, any longer a vibrant tradition that transmits “the light of the Lord.” If that light is to be sought out nonetheless, he expects his readers to do so in a personal way.

This is likely the reason that Sacks takes pains to emphasize the gentler aspects of interpersonal relationships, such as “compassion, generosity, kindness, understanding, forgiveness, the opening of soul to soul.” It would seem that the traditional God of the Bible and rabbinic thought—and also that of Crescas—was rather more complex than this, a fully developed personality whose inner life and relationships contained some darker aspects too. While an emphasis on the positive made it easier for Sacks to offer his ideas to his readers, he might have been able to provide them with something more powerful by presenting God as a personality to be struggled with as well.[31]

In his book, Sacks explicitly invokes Maimonides as his classic rabbinic role model. Maimonides, as Sacks describes him, rejected absolute naturalism and preserved all the essential aspects of the tradition intact. Maimonides’s approach, according to Sacks, put sensible limits on the claims of tradition and reason alike. The ambiguous nature of the Maimonidean corpus certainly allows for this reading; when such an understanding is combined with Maimonides’s enormous rabbinic stature, he becomes the natural choice as a role model for many traditional Jews who want to embrace the best of both worlds. In this, Sacks went down a well-trodden path.

And yet, this “traditional” understanding of Maimonides is not quite as traditional as it seems. It is mainly because of our cultural distance from the Middle Ages that so many traditional Jews today are able to read Maimonides and not be overwhelmed by the subversive implications of his writings. To a large degree, those who welcomed Maimonidean theology in his own era were those who rejected biblical and rabbinic conceptions of God, Israel, and the Torah. Those who criticized the Maimonidean corpus, or rejected it outright, tended to regard it as a perversion of the Jewish tradition. In other words, the wide-ranging acceptance of a moderate and traditional understanding of Maimonides is very much a historical anachronism.

Therefore, it may be that Crescas is the best precedent to the approach that Sacks argues for. Maimonides’s perceptive medieval critics (among them Crescas and Duran) were far from convinced that the Maimonidean corpus as it stood was really quite so innocent or benign as Sacks describes it. It was Crescas, not Maimonides, who openly critiqued Aristotelian axioms with integrity, and that was what enabled him to show that rational inquiry is just one way—and certainly not the most important way!—for human beings to understand existence and purpose.[32] It was Crescas, not Maimonides, who labored to preserve traditional biblical and rabbinic conceptions of God, Israel and the Torah in the face of severe persecution that was abetted by a cosmopolitan rationalist onslaught. It is Crescas who was clearly and unambiguously a defender of tradition, not Maimonides.

Furthermore, it was Crescas and not Maimonides who was able to reach beyond the reigning intellectual outlook of his time and open the door to something truly new. Maimonides was willing to radically reinterpret the Jewish tradition in accordance with the reigning philosophy, but Crescas refused. His was a double refusal: He refused to compromise the integrity of tradition, but he equally refused to compromise scientific integrity and rigor. It was precisely this combination that allowed him not only to remain loyal to the tradition, but also to become an original thinker on the cutting edge of science. In particular, what drove him to discover new scientific perspectives was his very refusal to compromise the truth of Torah as he saw it in favor of the regnant view among the educated class in his time. This can and should be an inspiring model of intellectual integrity for traditional Jews today.

It is true that Crescas is not well known for these positions in traditional Jewish circles, and that they are sometimes imputed to Maimonides instead (rightly or wrongly). It is likely that Crescas’s lack of prominence since the 15th century is partially the result of stylistic, organizational and conceptually challenging aspects of his book. An even more significant factor may have been his inability—despite his declared intention—to compose a revolutionary halakhic work that would compete with Maimonides’ Mishneh Torah, a loss which meant that even his very name eventually became unfamiliar in rabbinic circles (although his rabbinic stature was enormous in his own time). As the Zohar states, “Everything depends on fate, even the Torah scroll in the Ark.”[33]

But perhaps fate can be changed. Crescas’s life and learning potentially carry a powerful message for traditional Jews today. Unlike Maimonides it was he who insisted, clearly and consistently, that there must always be balance: Tradition and rational inquiry are two different ways of knowing. A scholar must pursue each of them with modesty and never allow one to subjugate the other.

[1] Still best presented in Harry Austryn Wolfson’s magisterial work, Crescas’ Critique of Aristotle (Cambridge: Harvard University Press, 1929). More recently, see Warren Zev Harvey, Physics and Metaphysics in Ḥasdai Crescas (Amsterdam: J.C. Gieben, 1998); Rabbi Hisdai Crescas (Jerusalem: Zalman Shazar Center, 2010) [Hebrew].

[2] On Crescas’s theology, see Natan Ophir, Rabbi Hasdai Crescas as Philosophic Exegete of Rabbinic Sources, Ph.D. diss. (Jerusalem: Hebrew University, 1994) [Hebrew].

[3] On philosophical antinomianism among the Jews of Spain at the time, see Eric Lawee, “The Path to Felicity: Teachings and Tensions in ‘Even Shetiyyah’ of Abraham ben Judah, Disciple of Hasdai Crescas,” Mediaeval Studies 59 (1997): 183-223, at 194ff. In terms of Crescas, see Harvey, Rabbi Hisdai Crescas, 45 and 47 (bottom). The argument was made strongly by Yitzhak Baer (Toledot ha-Yehudim bi-Sefarad ha-Nozrit [Tel-Aviv, 1965], 321-323), yet Harvey suggests that Baer may have overstated the point because Crescas began to write Or Adonai well before 1391. Still, it should be kept in mind that there was harsh persecution (if less drastic) before 1391 as well. Despite his hesitation, Harvey makes a good case that Crescas gives very strong, almost blatant hints to this in the introduction to Or Adonai, even if he isn’t explicit.

[4] On Duran and his main philosophical work Magen Avot, see my Ph.D. dissertation, The Book of Abraham: Rabbi Shimon ben Zemah Duran and the School of Rabbenu Nissim Gerondi (University of Haifa, 2006). The basic contrast between Crescas and Duran is described there in the introduction (9-15) and is the basis for the general description here.

[5] See Joseph Karo’s introduction to Beit Yosef; Kadish, Book of Abraham, 5 n. 21; and Yoel Katan’s introduction to Sefer ha-Tashbaẓ: Teshuvot Rabbi Shim`on bar Ẓemaḥ Duran (Jerusalem: Makhon Yerushalayim, 5758), 19-59.

[6] On “books of principles” in general, and on the intended meaning of the structures of Or Adonai and Magen Avot, see my “Jewish Dogma after Maimonides: Semantics or Substance?” Hebrew Union College Annual 86 (2015): 195-263.

[7] Duran’s testimony about this literary activity is described in Kadish, Book of Abraham, 9.

[8] See my “Jewish Dogma after Maimonides” for a fuller discussion.

[9] Thirteen is the number to be found in the final version of the book. On the changes that Crescas made to the fourth treatise, see Ophir, 64.

[10] On the popular success of the works of Crescas, Duran, and Albo, see Kadish, Book of Abraham, 11-13. On Maimonides’ thirteen foundations of the Torah as the basis of a simple catechism and the outlook promoted later medieval formulations of that catechism, see “Jewish Dogma after Maimonides” pp. 206-207; Eli Gurfinkel, “Ha-Issuq ba-`Iqqarim aḥarei ha-Rambam: Bein Reẓef le-Temurah,” Alei Sefer 22 (2011): 5‒17.

[11] Magen Avot (Livorno, 1785), 35b.

[12] On the barnacle goose and the tree-woman (or tree-man) in ancient and medieval sources, see Natan Slifkin, Sacred Monsters: Mysterious and Mythical Creatures of Scripture, Talmud and Midrash (Jerusalem: Gefen Books, 2011), 311-329.

[13] Kadish, Book of Abraham, chapter 5 (123-150).

[14] Ibid., chapter 6 (151-178).

[15] Ibid., 68a.

[16] The translation is from A Maimonides Reader, ed. Isadore Twersky (NY: Behrman House, 1972), 413.

[17] Guide of the Perplexed, I:2; II:30.

[18] For a solid discussion see Sarah Klein-Braslavy, Maimonides as Biblical Interpreter (Boston: Academic Studies Press, 2011).

[19] On Crescas and Duran, see immediately below; for Nissim Gerondi, see Derashot ha-Ran ha-Shalem, ed. Leon Aryeh Feldman (Jerusalem: Mossad Harav Kook, 2003), I (p. 39), VII (pp. 255-256).

[20] Magen Avot, 1a-b. The subsequent description is based upon Kadish, Book of Abraham, chapter 2 (25-57).

[21] Ibid., IV:3, 6.

[22] For a good survey of the opposing positions on angels, see Menachem Kellner, Maimonides’ Confrontation with Mysticism (Oxford: The Littman Library of Jewish Civilization, 2006), 265-285. Regarding demons, see the literature cited there and related comments, 284-285 n. 77.

[23] The summary that follows is based on Kadish, Book of Abraham, chapter 3 (58-88).

[24] This extremely long chapter appears separately in most manuscripts, and it was published separately as well under the title Keshet U-Magen (Leghorn, 1790). There is a critical edition by Murciano Prosper, Simon ben Zemah Duran: Keshet u-Magen: A Critical Edition, Ph.D. diss. (New York University, 1975).

[25] Kadish, Book of Abraham, chapter 3.

[26] Some quality examples in English might include (1) Nissan Mindel’s In Nature’s Wonderland, which appeared as a column in the Chabad children’s periodical Talks and Tales, published from 1941 to 1989 by Kehot Publication Society; (2) Rabbi Berel Wein’s volumes on Jewish history; (3) the late Rabbi Dr. Abraham Twersky’s numerous volumes on popular psychology.

[27] Some of the prominent examples of this have been Jewish physicists who attempt to tackle cosmology and evolution. Among them are the late Cyril Domb, who founded the British branch of the Association of Orthodox Jewish Scientists and Bar-Ilan University’s Journal of Torah and Scholarship (Bekhol Derakhekha Daehu or BDD); Prof. Natan Aviezer of Bar-Ilan; Prof. Herman (Yirmiyahu) Branover, who founded the journal B’Or Ha’Torah which is devoted to Torah and science; and the late Prof. Yehuda (Leo) Levy, Rector and Professor of Electro-optics at the Jerusalem College of Technology who also wrote widely on Torah and science. The book Challenge: Torah Views on Science and its Problems (New York: Feldheim, 1976), which was co-edited by Aryeh Carmell and Cyril Domb, is a classic work of this type.

[28] The summary that follows of Steinzaltz’s initial remarks is from personal memory. I have not found a recording or a transcript of that lecture.

[29] The Great Partnership: God, Science and the Search for Meaning (London: Hodder & Stoughton, 2011), 78-79.

[30] Sacks, 72-74.

[31] Michael Wyschogrod offers something like this in The Body of Faith: God in the People of Israel, 2nd edition (New York: Rowman and Littlefield, 1996).

[32] See Warren Harvey, Hasdai Crescas’ Critique of the Theory of the Acquired Intellect, Ph.D. diss. (New York: Columbia University, 1973), especially 38-40; 184-188. The topic is discussed at unusual length in Or Adonai II:6. Duran’s conclusions about the value of the intellect and the purpose of the Torah are similar to those of Crescas (see Kadish, Book of Abraham, 140-141), yet they are really no more than assertions. The impetus to crown intellect as the highest value is at the very core of medieval rationalism, but Duran lacked the desire and the intellectual bent to effectively challenge that core.

[33] Idra Rabba, Parashat Naso 134a.