Competing Claims for Truth:
Medieval Judaism and Christianity in Conflict
Professor of Medieval Jewish Philosophy at
Ben-Gurion University, Beer Sheva, Israel
College, February 6, 2003
See "Competing Claims for Truth: Medieval Judaism and Christianity in Conflict" on streaming media
I would like to talk tonight about one aspect of the relation between Jews and Christians in the Middle Ages, namely the polemical aspect. That does not mean that there were not mutually enriching relations between Jews and Christians in the past. For instance, if one looks at the relationship between Jews and Christians in Provence (southern France), one notices that despite the conflict between the two religions, there was also a close relationship between Jewish intellectuals and Christian intellectuals. Judah ibn Tibbon, the founder of the Tibbonide family of translators who were cultural transferors of Spanish and Andalusian Jewish culture to the south of France, wrote in his ethical will to his son about how at the son’s wedding, they were honored by the priests, and the bishops and the deacons who all came to the wedding. There were also professional relationships between Jews and Christians in Provence, such as in the fields of translation, science and astronomy. Throughout the Middle Ages, there were positive relationships between members of the two religions, but in the discussion tonight I want to focus on the polemical literature written by representatives of each side, and more specifically on the methodologies employed by the polemicists to substantiate their arguments. So, what I will be trying to do here is to enter into an epistemological question, "How does one determine the truth?" I will argue tonight that one of the reasons that this literature flourished without either side's scoring a decisive victory is the fact that neither side was able to develop a convincing epistemology or methodology of argumentation.
Before discussing this argumentation, we have to look a little bit at the history of the polemical literature. The Jewish-Christian debate is as old as Christianity when immediately after the crucifixion, the first Christians, who were themselves Jews, began spreading the good news of the messianic redemption among other Jews. Soon Christianity expanded to include both Gentiles and Jews, as a result of both the Jewish-Christian failure to convince other Jews and also the growing recognition that Jesus’ ministry was intended for all of humanity. Of course, it was Paul who is central to this development. It was also Paul who wrote many critical comments about Judaism. Whereas it is unclear whether these comments were meant to be directed at Jews, at Jewish-Christians or at Judaizing Gentile Christians, still Paul’s words contributed to the ongoing Jewish-Christian debate of future centuries and to the developing negative Christian view of Jews and Judaism. Now after Paul, there were other Christian missionaries who were active among Jews and pagans, and these Christians composed quite a number of polemical treatises to try to convince themselves and others of the truth of the new religion. This produced a genre of anti-Jewish writings which is known as Adversus Judaeos, or "against the Jews" and which became a popular literary form among Christian writers.
These anti-Jewish tracts were probably intended more for budding missionaries than for the Jewish readers themselves. Undoubtedly their contents were expressed to Jews by Christian interlocutors. It is probable that Jews in the first few Christian centuries did not know all the details of Christian theology, and judging from all the Christian groups which would later be declared heretical, apparently not even all Christians knew all the details of Christian theology. Nevertheless, Jews were aware that they were the objects of Christian missionizing activity. Now, these early Christians did not succeed very well in convincing Jews of the truth of Christianity and converting them to Christianity. And in the early centuries Jews tended not to respond to these threats, or at least we do not have many literary remains of Jewish responses to Christianity.
Already we see in the New Testament that Jews are portrayed as ridiculing Jesus’ messianic claims. "If he cannot save himself, how can he save others?" We know other early Jewish anti-Christian arguments from Christian material, for instance from Christian apologists, such as Justin Martyr, and from the Church Fathers. These Christians repeated Jewish arguments against Christianity in order to refute them. So we know that there were Jews arguing against Christianity, but we have very little evidence of this from Jewish texts. We have some texts, such as the Jerusalem Talmud from around the year 400 and the Babylonian Talmud from year 500 and 600, which include anti-Christian material, but these works generally ignored Christianity, even though occasionally they alluded to points of conflict between the two religions.
An extant book from some time in the early period (we do not know exactly from when) is a Jewish parody of the New Testament called Toledot Yeshu, the story of Jesus. It was composed not as a polemical work as such with argumentation, but rather as a criticism of Jesus by means of parodying the New Testament accounts of his life. So, in the first 800 years or so of the relationship between Jews and Christians, we have Christian polemical literature, but very little Jewish polemical literature. That changes in the ninth century or so, as a number of Jews turned toward a polemic with Christians. The first of these compositions were written in Arabic in Islamic countries, where it was officially forbidden for Jews to become Christians or Christians to become Jews. This fact demonstrates that there does not have to be a missionizing threat by Christians in order for Jews to respond to Christianity or to attack Christian doctrines.
When the center of Jewish life turned from Islamic countries to Western European Christian countries, the debate intensified. A great watershed in this respect was in the 13th century when Christians put a much greater emphasis on mission to the Jews, and they established missionary schools. Many Christians poured through Jewish Rabbinic and midrashic literature to find possible proofs of Christianity. Public debates were initiated in Paris in 1240, in which the Talmud was basically put on trial and as a result of which the Talmud was burned in 1242; and in Barcelona in 1263, where Nahmanides, the foremost Jewish authority of his age, was forced to come and debate against the Jewish apostate Pablo Christiani. New polemical strategies were developed by Christians and eventually Christians gave Jews the choice of death, conversion or expulsion. Part of this historical process was the proliferation of treatises which we can call specifically polemical treatises.
These treatises represent an asymmetrical relationship between the two religions. After all, Christians were trying to convert Jews or convince Jews of the truths of Christianity, whereas Jews were basically defending their right to remain as Jews and to convince other Jews not to convert. So even though, as I said, there are such polemics in the absence of a missionary threat, by and large the Jewish literary critique of Christianity is a product of the need to defend Judaism and Jews against Christian attacks. The heyday of the polemical literature in Western Europe was the Middle Ages. With the expulsion of Jews from Western Europe (by the year 1500 there are almost no Jews left there), the debate continued in Italy and Eastern Europe. The debate continues even today, with each side's producing controversial literature. As in the medieval case, one cannot necessarily say that the polemical literature represents the whole story of the current relationship between Jews and Christians, especially since today neither religion is monolithic. If one does look at the modern polemical compositions, however, one is struck by significant parallels between the medieval and the modern literature.
Now this literature, which I study, is a very problematic genre. We do not necessarily know why people were writing. Were they writing to their own community? Were they writing to the other community? Most Christian writers wrote in Latin which most Jews could not read. Most Jewish writers wrote in Hebrew, which most Christian readers could not read. We do not know how effective this literature was. People ask, "Was anyone ever convinced by any of these writings?" Unfortunately, there is no clear answer. The nature of this polemical literature is also somewhat problematic. It is not necessarily intellectually uplifting. Many of the polemicists indulged in vulgarity or used accusations which had no basis in fact. Of course, this is true not only concerning inter-religious polemics; one could think as well about political polemics. In pre-election debates between candidates, often the candidates accuse their rivals of all kinds of nefarious deeds. Afterwards they shake hands and they are all friends, something which did not happen in the medieval debates. But, this is what polemics is about: trying to use any argument in one’s arsenal either to convince the other side or to convince one’s own side. I think also that to a certain extent, this literature served not only for enlightenment, so that people would know different arguments of each side, but also as entertainment. After all, in the Middle Ages, people did not have television, video and internet to entertain them.
Another aspect of the polemical literature is what I call "all’s fair in love, war and polemics." Many times what an author writes in his work does not represent his true belief. We have authors who in a philosophical work say one thing and in a polemical work say something quite different. Authors make up public debates that never occurred in order to give a literary framework for their work. Although the literature itself is problematic, that does not mean it is not important. It leads to an understanding of many aspects of intellectual history. It gives an insight into popular religion, what different arguments were bandied about by the different sides. It gives us an idea of interreligious understanding and misunderstanding. It is an aid to understanding certain historical trends.
Given that short, cursory and inadequate introduction, what I would like to do is actually look at the argumentation contained in the polemical literature. What are they saying, what are the arguments, what are the methodologies for using the argumentation? First of all, I would say that there are three types of arguments being used. The first type is exegetical, namely how to interpret a holy text. The second might be called historical or social. And a third might be called rational.
Let’s start with the exegetical. The holy texts which were looked at were the Hebrew Bible, which the Christians consider the Old Testament, the New Testament and Rabbinic literature. The polemicist's basic purpose was to show that the holy texts substantiate his position and undermine his opponent's position. Christians would use the Hebrew Bible and Rabbinic literature, the post-biblical Jewish literature, as a proof of Christianity. So, if the Book of Isaiah talks about the suffering servant, Christians would identify that servant with Jesus. If the Midrash implies that the Messiah had already come, then Christians would use that to say to Jews that they no longer have any messianic hopes. Jews on the other hand would argue from the New Testament. They would say that the New Testament rejects the claims of contemporary Christianity. After all, Jesus said he came not to abolish the law, and he, himself, observed the law, but contemporary Christians did not. Christians did not generally argue against Jews for the truth of Christianity from the New Testament because Jews did not accept the New Testament, but they did argue from the Hebrew Bible and from Rabbinic literature.
Historical/social arguments are based on the vicissitudes of history and the attempt to justify one religion over the other on the basis of history – let’s say military victories - or they deal with questions as to which religious society is a better society. And if one's society is better than the other's society, then perhaps her religion is a truer religion.
Rational arguments are divided into what I call common sense and philosophical arguments. A common sense argument might claim that God would not require the murder of His son in order to bring redemption. A philosophical argument against a triune God, who is both three and one, might claim that it is logically absurd to believe that one aspect of the uncaused, immutable God has a causative relation with other aspects. Both of these arguments are claimed to be based on reason, but one is more like "God would not do such a thing," whereas the other one is based more strictly on the philosophical question of what doctrines are consistent or contradictory or self-contradictory.
In each of the three types of argumentation, the question of veracity arises. There is an epistemological question of truth. It seems to me that neither side was successful in developing a convincing, objective methodology of proving their argumentation. Let me give examples first from exegesis and history, and then I will concentrate on philosophy, which is of more interest to me.
Let’s look first at exegesis. Around the year 1170 Joseph Kimhi, who composed one of the first Jewish anti-Christian polemical works in Hebrew in Christian Europe, quoted a Christian as saying "You," namely the Jews, "understand most of the Torah literally, while we understand it figuratively. Your whole reading of the Bible is erroneous for you resemble him who gnaws at the bone while we suck at the marrow within. You are like the beast that eats the chaff while we eat the wheat." What did the Christian mean? He said that although the Bible has laws, saying for instance that one should circumcise himself, that does not literally mean circumcision. Those who take it literally are missing the point. Circumcision means purification. The paschal lamb had nothing to do with taking a lamb and slaughtering it; it has to do with a prefiguration of Jesus. Sabbath prohibitions are not necessarily meant to be Sabbath prohibitions. The same with purity laws. When the Bible, the Torah, the Pentateuch talk about "eternal" laws, eternal does not mean "always." The Christians claimed to interpret the Hebrew Bible correctly by understanding its allegorical nature, its figurative nature. Jews were said to be too literal. Even though these Christian accusations of Jewish literalism may be true in certain respects, the Christians themselves were certainly capable of interpreting very literally those verses which they wanted to. I mentioned Isaiah's suffering servant of the Lord before. "His grave is among the wicked, he suffered for our sins." Do Christians say that is allegorical? No, they say it is literal; that actually happened. Psalms says that we are conceived in iniquity. Christians take that very literally, meaning that each human being is born with original sin.
So, there are many Hebrew Bible passages taken extremely literally by Christians. And Jews, on the other hand, understand any number of scriptural passages as being allegorical. In the future, the wolf will lie down with the lamb, but for most of the Jewish rationalists, that does not mean that there will be a change of nature. When the messiah comes, the only way that the wolf and the lamb will live together is if there is a new lamb every day. The law is to be taken literally, as incorporated in the oral law, which itself is not always a literal interpretation of the biblical law. When it comes, however, to historical accounts, or descriptions of God, some can be taken literally, some can be allegorical. The limits of allegory was one of the subjects of the Maimonidean controversies in the 13th and 14th centuries. But, Christianity has the same problem. Christian rationalists also have to accept certain passages of the Hebrew Bible as allegorical and certain passages as literal.
What about the New Testament? Jews said to the Christians, "You interpret the New Testament much too literally." When Jesus, at the Last Supper said, "This is my body, this is my blood;" what did the Medieval Christians, at the time Catholics, say? They said that Jesus literally meant that the bread became his body, the wine became his blood. What did Jews say? "No", this is meant allegorically. He did not mean this literally to be the fact. When Jesus said "I did not come to abolish the law," do Christians take that literally? No, they take it allegorically. And on the other hand, when the Midrash says that the messiah was born on the day the Temple was destroyed, Christians say that that meant that the messiah has already come and, therefore, there is no more Jewish hope, whereas Jews say that this has other meanings rather than a literal application.
Although the exegetical debate made up the bulk of the argumentation in the Medieval polemics, there was no agreed upon methodology of exegesis. Although the polemicists occasionally attempted to establish exegetical criteria, such as determining when one should interpret scriptural passages literally and when one should interpret them allegorically; and there are also attempts at contextualization of verses so that exegesis is not totally arbitrary; the bottom line seems to be in all these debates that first one has his theological commitments, then he interprets holy text. And if that is the case, there certainly is no strict methodology of how to interpret.
Let’s look now at history. In Judah Halevi's Book of Kuzari (12th century), the author quotes the King of the Khazars who converted to Judaism (this is based on historical facts but Halevi's account is fictional) as saying "If Judaism is the true religion, how is it that Christians and Muslims are strong and the Jews are weak?" So what does Judah Halevi, or his representative in the debate, answer? He says that when the other religions were weak, they glorified weakness. Therefore, the original Christian martyrs were taken by Christians as proof of the truth of Christianity. Muhammad had to flee from Mecca to Medina. This was not seen as an admission of defeat or of being wrong. In fact, when the Jewish representative says that "Our being weak is indeed a sign of our belief in God;" the king replies, "Yes, but if some day you will be strong, you might turn around and do to your enemies exactly what they are doing to you." The author could only admit that the King's statement is probably true.
The problem with historical arguments is that, when one is weak, dying for God proves the truth of religion; when one is strong, then killing for God proves the truth of the religion. So if both dying and killing are proof, it seems to me that there is no proof. History has not ended yet, so how can one argue from history? And one generation’s absolute truths and absolute certainties - manifest destiny, divine right of kings, white man’s burden are good examples - might be accepted as God’s will in one generation, but were seen in another generation as against God’s will. Does that stop people from theological judgments? No. In fact both Jews and Christians agreed that Jewish exile was a result of sin. The difference of opinion was, "What was the sin for which Jews were in exile?" For the Christians, it was the sin of the crucifixion, of deicide; for Jews, it was the sin of not being sufficiently observant and sufficiently believing in God. The fact the medievals understood Jewish exile as a sign of punishment of Jews for the crucifixion has its influence to this day and has made it difficult for many Christians to accept a reborn Jewish state, especially a strong triumphant one. In addition, when Jews and Christians are arguing from history, there is another player on stage, and that is Islam. Jews would say, "How could Christians claim exclusive truth on the basis of Christian strength when there are Muslims just as strong as Christians and now (at least after Saladin) they control the Holy Land?" This Christian-Muslim controversy, which is still being played out today, has strong roots in the Middle Ages and was pointed out by Jews as a sign of the weakness of Christian argumentation from their own strength.
What about social arguments? Here Jews claimed that Christians were immoral. They engaged in murder, theft, sexual sins; priestly celibacy was a sham. As opposed to Christian sins, Jews were hospitable, they did not let their children use foul language, they were charitable. Jewish society was much better than Christian society from the Jewish point of view. What did Christians answer? Christians claimed, "No", the Jews were immoral. Jews lent at interest; Jews were untrustworthy. But this leads to the question, "How does one judge a society?" How does one say that a society as a whole is a better society than another one? And even if one could determine this fact, what would this tell us about the truth of religion? As it is, we tend to say that people who act as religionists but do something bad are not really representative of that religion. At least people try to claim that, so that, as said among Jews, the Sabbath observant thief is actually clean shaven under his beard. Rumor has it that members of the Mafia are good attendees of mass. On the other hand, there are people who do terrible things in the name of their religion; and even though one tries to say that they do not really represent their religion, still it is hard not to see that at least they think they are acting out of religious motives. What I am trying to say, though, is that the question of the truth of religion should not necessarily be a utilitarian or pragmatic one. Is truth determined on the basis of which religion produces a better society, assuming we can even determine which religion makes a better society? Or are there truth claims involved about the nature of the doctrines of religions? So it seems to me that historical/social arguments also have a problem of methodology.
Let’s look now at rational arguments, beginning with common sense arguments. One popular argument, one which originated in the Islamic world and is found, for example, in the Book of the Covenant by Joseph Kimhi, uses graphic descriptions of the indignities of gestation and birth as an argument against incarnation. Joseph Kimhi said, "Thus we do not profess this belief which you profess, for my reason does not allow me to diminish the greatness of God, be He exalted, for He has not lessened His glory, may He be exalted, nor has he reduced his splendor, be He extolled." We find these arguments in the Christian literature as well. Odo of Tournai, in the beginning of the 12th century, quoted a Jew Leo as arguing against incarnation from that point of view. But for the Christian, the gestation and birth did not involve indignities at all because Jesus was not touched by the female impurities, just as light can shine through garbage without itself becoming soiled. And even if it did, even if there were such indignities, all it proved was God’s great love for humanity. No one apparently seemed to doubt the assumption that the female innards are somehow repellant or repulsive; they argued merely as whether or not it was possible for God to undergo the process of birth.
Or take an example from the Christian point of view. Anselm of Canterbury in the late eleventh century developed the rational understanding of the need for incarnation in order to have a God-man sacrifice. Now, Anselm seemed to think this doctrine was fully consonant with human reason, and reason demands this to be the case. In fact, his claim that Christianity is the necessary result of the use of reason led one of his followers, Peter Venerabilis in the middle of the 12th century, to deny Jewish humanity. On what basis? If the definition of a human is a rational animal, and anyone rational being will accept Christianity, then anybody who does not accept Christianity is not rational, and if a person is not rational, then this person cannot be a human being. On the other hand, Jews looked at this argument and said, "This does not make sense." Jacob ben Reuben, in the 12th century, explained it this way. He said that if a king hears that one of his subjects committed a terrible crime, does a king volunteer to take off his royal clothes, demean himself, and then have himself killed to atone for the sin of his subject? So, what looked like reason, ratio in Latin, or common sense, for one person, definitely did not look reasonable for someone else.
I would like to turn to the philosophical arguments, which are my major interest and probably the bulk of the methodological part of the talk. In these polemics, there are true methodological discussions, as one would expect from philosophers. Specifically, the philosophical part of the debate revolved around the question, "Which theological doctrines are possibly true, and which ones are indubitably false?" The Jewish polemicists argued that a religion which teaches impossible or self-contradictory doctrines is ipso facto false. To their mind, Christian doctrines are probably considered rationally impossible and therefore Christianity is, of necessity, a false religion. So, in order to validate this argumentation, it was necessary to establish epistemological categories concerning truth claims, categories in which a distinction between imagination and intellect played a role in this discussion. The polemicists had to determine which of these two categories – imagination or intellect – would determine possibility and which one provides the wherewithal to support or reject specific religious doctrines.
This discussion begins with Maimonides in his Guide of the Perplexed in the late 12th century, and it occurs in a polemical context but not in an anti-Christian polemical context. Rather, Maimonides was arguing against the Jewish and Muslims followers of the Islamic theology known as Kalam who, according to Maimonides, were not sufficiently scientifically rigorous in their theological discussions. Maimonides himself tried to navigate between the naturalistic and scientific theories of Aristotle, which he asserted were based on the intellect, and claims of theology. According to Maimonides, these theological claims of the Kalam were based on the imagination. In light of this distinction, Maimonides argued that only the intellect determines possibility, not imagination. Although one could presumably imagine an elephant the size of a gnat, but that would not make such an elephant possible, since the enormous size of the elephant is part of its essential definition. On the other hand, Maimonides says that it would be difficult to imagine two people standing on either side of a ball without one of them, if not both of them, falling off; and yet, on the other hand, we know that that is what happens on the earth. Although Maimonides knew the intellect and not the imagination was the arbiter of possibility, he himself was incapable of drawing firm boundaries between the possible and the impossible. What he called the Kalam theory of admissibility – that anything imaginable is possible – he said is "not a theory one hastens to reject in its entirety with nonchalance." Now Maimonides also said, "Would that I knew how one could make the final adjudication between the two classes of possible and impossible."
As I said, Maimonides was arguing against the Islamic philosophy called the Kalam, but later readers saw that his argumentation could be used against Christianity as well. Among the examples proffered by Maimonides as impossible beliefs, disavowed by the intellect, are that God should bring into existence someone like Himself, or should annihilate Himself, or should become a body, or should change. A philosophical polemicist against Christianity could easily relate these impossibilities with the Christian views of the generation of the Son and procession of the Spirit, the incarnation, and the putative death of the son of God on the cross; and it is possible that even Maimonides, himself, was thinking in that direction. There are other impossibilities that Maimonides mentions such as substance's becoming accidents, or accidents' becoming substance, or for a physical substance to exist without accidents. Here it is highly unlikely that Maimonides was actually referring to Christian transubstantiation, which became the orthodox belief only eleven years after his death in 1215 at the Fourth Lateran Council. Nonetheless, later Jewish polemicists used these as examples of impossible beliefs, referring specifically to transubstantiation.
It was during Maimonides’ lifetime that Jews in Western Europe began to write polemical treatises against Christianity. His contemporaries, whom I have mentioned, both Jacob ben Reuben and Joseph Kimhi, did try to use rationalistic argumentation. For instance, Joseph wrote, "Incarnation is rejected by the intellect because it is unseemly for God to suffer the indignities of gestation and birth," but he did not offer any philosophical proofs for that assertion. Jacob ben Reuben referred to trinity, incarnation, virgin birth, but did not come up with a theory of possibility. Both of these used the Hebrew term sekhel, reflecting the Latin ratio, a central term in the 12th century discourse about the rationality of Christianity. These Jewish authors were arguing that indeed Christianity is not rational; if there is a rational religion, it is Judaism, not Christianity.
Now, a true theory of possibility develops only toward the end of the 14th century in Spain, probably as a result of Christian successes in converting Jews – often, but not always, by means of force such as in the riots of 1391. Also there is the influence of Averroism, which distinguished between philosophy and religion so that a philosophical defense of religion was considered impossible. Thus, the Jewish philosophers understood that they could not prove the truth of Judaism by use of reason, but they were hopeful of finding a way of rationally refuting Christianity so it would be less attractive to their wavering co-religionists. The result was the enunciation of an epistemological principle: although reason cannot prove the truth of religion, as per Averroes, it can disqualify a false religion by demonstrating the rational untenability of its doctrines. Building upon another passage of Maimonides, what these philosophical polemicists did was to distinguish between what they called natural impossibility, such as dividing a sea or turning a rod into a serpent, and logical impossibility, such as the existence of a square whose sides and diagonal are the same length or a triangle the sum of whose angles was more than two right angles. In the context of the debate with Christianity, the Jewish polemicists argued that a true religion may teach naturally impossible doctrines, since God has the power to change nature, but it may not teach logically impossible doctrines, since that which is truly impossible is not subject to divine power. Christian principles such as trinity, incarnation, transubstantiation and virgin birth were then subjected to philosophical analysis in the hopes of demonstrating that they are logically impossible – contradicted by the intellect as well as being self-contradictory and, therefore, they could not be taught by a true religion.
From the Jewish point of view, Christianity, which promulgated such logically impossible doctrines, is of necessity a false religion. Judaism was claimed to hold no such logically impossible, self-contradictory doctrines. Those doctrines that Judaism does teach that appear to be impossible require merely the abrogation of what is naturally impossible. Judaism is, therefore, a possibly true religion. One could go a step further. If there are only three possible candidates for being a true divine religion – namely Judaism, Christianity and Islam – and Christianity is eliminated for the beliefs I mentioned and Islam has other rational problems according to some Jewish polemicists, that leaves only Judaism. This is the tack taken by Joseph Albo in the 15th century, even though he did not develop the anti-Islamic polemic to any extent.
The theory that there is a difference between the rationally impossible and the logically impossible is actually reminiscent of the Kalam’s view as reported by Maimonides that the possible is determined by imagination, and as such it would be open to Maimonides’ Aristotelian critique, namely not everything which is imaginable is possible. So why is resurrection of the dead, which is against nature but imaginable, any more acceptable than an elephant the size of a flea, which Maimonides rejected as impossible? If one holds that the laws of nature reflect logical necessity, as the Aristotelians tended to do, then there cannot be a difference between natural impossibility and logical impossibility. This is the reason why traditional Jewish beliefs in miracles, such as creation ex nihilo, resurrection and the splitting of the Red Sea, are problematic for Maimonides, and why many of Maimonides’ readers are somewhat skeptical of his actually having held those views, despite his ostensible support of them. Once nature exists following necessary laws that reflect divine wisdom, a break in nature would be impossible even if imaginable. For a true Aristotelian, and thus maybe for Maimonides himself, resurrection of the dead is no more possible than an elephant the size of a flea or incarnation of the second person of the trinity.
Now it seems to me that the Jewish philosophical polemicists were aware of the problematics of their methodology, namely, this distinction between natural impossibility and logical impossibility. They did not want to use the term imagination, which Maimonides had said could not be used. As a result, they used another term, representation, tziyyur in Hebrew. Could a belief be represented or not? This idea of intellectual conception also goes back to Maimonides in his discussion of divine attributes, where he says “belief is not the notion that is uttered, but the notion that is represented in the soul when it has been averred of it that it is in fact just as it has been represented.” In order to have faith, one has to be able to represent that faith, have an intellectual representation of that faith. In the same context, Maimonides says that the statement of the mistaken believers that "God is One but has attributes" is like the doctrine of the Christians who say that "God is One but also Three, and the Three are One." So, from Maimonides’ point of view, neither view, namely attributes or Trinity, can be represented in the mind and therefore neither one can be true. A true belief is one which is intellectually conceivable. False beliefs like the Trinity are those which are not intellectually conceivable. Thus, later polemicists made intellectual conceivability, or representation, and not imagination as a determinant principle for possibility and impossibility. If a belief can be represented intellectually, then, "Yes, it is possible;" if it cannot be represented intellectually, then, "No, it is not possible." So, we see that Jews distinguished between Jewish beliefs, which they said were possible, and Christian beliefs, which they claimed were not, even if such a distinction might be considered arbitrary or philosophical questionable.
How did the Christians respond to the Jewish claim of Christian irrationality? First of all, it is obvious that many of the Christians knew the philosophical problems related to their doctrines even without Jewish prompting. Many of the Christian beliefs, especially the mysteries, were understood to be problematic vis-à-vis the intellect. Medieval Christian philosophers developed a vast apologetical literature answering internal Christian doubts about the rationality of their beliefs, literature which is most likely not related to the Jewish critique except perhaps as a source for some of the Jewish argumentation. Take, for instance, Thomas Aquinas, who struggled with many of these same problems in the mid-thirteenth century, 100-150 years before they appear in Jewish literature (especially the arguments concerning transubstantiation). The standard Christian philosophical claim, as developed by the rational apologists, was that Christian doctrines, even if they appear to be rationally questionable, can be defended by reason and, therefore, are not to be dismissed out of hand. Christian philosophers, very much like the Jewish ones, argued that the seemingly impossible doctrines are not logically impossible. A good example is the question of the union of God and man in the person of Jesus. Since none of the models of union known from the Aristotelian literature was sufficient to explain such a union, Thomas theorized something called a hypostatic union. A hypostatic union is one in which one hypostasis of God can be united with a human being. Even in the absence of a specific Jewish challenge, Christian thinkers felt a necessity of proving the possibility of the truth of their doctrines.
There is also another direct response to Jewish arguments. We see in the Jewish polemical literature that Christians were aware of the Jewish attack on the rationality of their beliefs. If we can rely on these sources, some Christian interlocutors reacted to the Jewish assault on their religion by arguing that Christian doctrines are no more impossible than Jewish ones, and, hence, Judaism is no more intellectually respectable than Christianity. I can give a number of examples. Nissim of Marseilles from the 14th century quoted a Christian as saying, "Why is it that you believe in resurrection and creation and deny incarnation? In fact, creation of the world ex nihilo makes less sense than incarnation because incarnation is creation from something, whereas creation of the world from nothing has no basis that is possible." Nissim responded by saying that the Christian beliefs are those that undermine religion, since the minute one believes in an incarnated God, God is no longer a necessary existent. Resurrection of the dead and creation do not undermine religion. In fact, they are politically useful beliefs for the masses. For Nissim, the distinction between prima facie impossible Jewish beliefs and actually impossible Christian beliefs is the distinction between the theological and politically useful and the philosophically abhorrent. Similar questions are found in the contemporary of Nissim, the 14th century Provençal Joseph ibn Caspi. Again the Christians are quoted as saying: "How can you believe in creation and resurrection and reject incarnation?" Caspi argued that Jewish beliefs do not imply any deficiency in God whereas incarnation does imply such inadequacy. Whether attributing inadequacy to God is a philosophical problem, as would appear in Nissim’s work, or a theological problem is not clear because Caspi says: "God forbid, halila, that there be in the divine substance potentiality for evil or deficiency." We have other authors as well who raised a similar question: how is it, according to the Christians, that Jews are willing to believe in some impossible beliefs and not other impossible beliefs, such as the incarnation?
What is common to these discussions of possibility is that the Jewish philosophical polemicists struggled to find a way of distinguishing between problematic Jewish beliefs and problematic Christian ones. As good Maimonideans, the polemicists asserted that the intellect is the proper determinant of possibility; and the intellect could distinguish between natural impossibility and logical impossibility. But also as good Maimonideans, they probably would have had to admit that they were not totally successful at distinguishing between the possible and the impossible. And with Maimonides, they could say, "Would that we knew how to determine the difference between the two classes." So, even in the realm of the strictly philosophical argumentation, an ironclad epistemological rule of distinguishing between impossible beliefs and possibly true beliefs escaped the polemicists.
We see from this discussion the two sides talked past each other for more than one reason. Not only do they start with different theological assumptions, but they also do not have an agreed upon methodology in pursuing their debate. It is not like a baseball game in which the ground rules are laid out in advance. It is not like a legal system in which there are clear ways of determining correct procedure. It is not like geometry with axioms and theorems. Perhaps that is what one might expect from theological questions which are not amenable to proof in the same manner as the sciences. This, however, did not stop the polemicists from defending their own religion and attacking that of their opponents. And it does not stop those of us who study the polemical literature from attempting to understand its contribution to the Jewish-Christian encounter.