How Tolerable is Cusa’s Tolerance? Revisiting Cusa’s Encounter with Islam

This paper will analyze Cusa’s approach to Islam as a test case regarding toleration. Firstly, we will establish toleration and its key components as tertium comparationis . Secondly, we will give a brief overview of Cusa’s main positions on Islam and (religious) diversity, including some shifts that occur within his sustained study of the Qur’an . Thirdly, we will apply the concept of toleration to some key points taken from two of Cusa’s works in which he engages in an imagined dialogue with Islam in order to identify his grounds for accepting, objecting to, and rejecting Islamic doctrines. We will argue that while Cusa’s irenic position and his concept of human nature remain constant principles regarding his toleration of Islam, Cusa’s application of the concept of rationabilitas plays a major role in shifting from tolerating to rejecting Islamic doctrines the more the latter are interpreted as heretical.

One could argue that nothing novel can be said about Nicholas of Cusa's approach to Islam, [2] given that his principal works that deal with the topic, namely De pace fidei from 1453, the letter to Juan de Segovia from 1454, and, finally, the Cribratio Alkorani from 1460/61, have been discussed extensively in scholarship, with a special focus on De pace fidei. 1 In terms of interpretation, certain trends can be observed. First, we see a long-standing [3] 1 See, for example, Burgevin (1969), Decker (1953), Decker (1962), Hagemann (1976), Haubst (1984), Euler (1990), Euler and Kerger (2010); Euler (2019). For an excellent comprehensive overview and new insights, see Levy, Tvrtković, and Duclow (2014). For a brief overview over the literature and the content, see also Gottlöber (2014bGottlöber ( , 2014cGottlöber ( , 2014a tradition to read Cusa's approach to different religions in general, and Islam in particular, as an example of late medieval/early modern toleration, especially with regard to De pace fidei (see, for example, Bocken 1998;Hoye n.d.). A similarly strong trend, however, can be identified which stands in opposition to this view. These perspectives either argue that Cusa actually is an example of an intolerant approach, and/or (sometimes connected with the first point) that those scholars who credit Cusa with a tolerant position read him in an anachronistic fashion, or maintain in general that Cusa did not contribute to the idea of toleration-at least not as we understand it today (see, for example, Krieger 2008). There are also positions that argue that the 'truth' may lie somewhere between these two extremes. Thus, Cusa scholar Walter Andreas Euler rightly states that if we were to ask about Cusa's stance on toleration, 2 the answer that is elicited will depend upon which text we look at; in them, we encounter a variety of perspectives, stretching from the irenic and inclusive approach of De pace fidei to the strong anti-Islamic statements in sermon CCXL. 3 Nevertheless, I would like to suggest there is a good reason to return to the question of [4] Cusa's approach to Islam within the context of toleration one more time as approaches in scholarship tend to be one-sided, often due to the fact that assessments of Cusa's thinking lack a well-developed concept of toleration, either using a general contemporary understanding that toleration means embracing or affirming difference, or embedding and assessing Cusa's position solely in the context of his time, claiming that toleration is too modern a concept to apply to Cusa. 4 Therefore, the goal of our paper will be to analyse Cusa's continued approach to Islam as [5] a test case regarding toleration. We will proceed in three steps: firstly, we will establish a framework with regard to the key components of toleration. This will enable us to set up toleration as a tertium comparationis which will allow us to analyse Cusa's encounter with Islamic doctrine in more detail but also to consider the shifts that occur with his concentrated study of the Qur'an. Secondly, we will give a brief overview of Cusa's main positions on Islam and religious diversity, as established in his three main texts on Islam. Thirdly, we will apply this framework, as developed in step one, to some key points taken from two out of the three works where Cusa engages in an imagined dialogue with Islam, De pace fidei and Cribratio Alkorani, to identify Cusa's grounds for 1) accepting; 2) objecting to; and 3) rejecting Islamic doctrines.
It is to be hoped that rather than judging according to contemporary twenty-first-century [6] 2 Even though Habermas indicates that he sees a difference between toleration (as the legal act of a government) and tolerance (as a form of behavior) in English, we will not follow this distinction, as most positions in scholarship use the terms interchangeably. Thus, for the following argument, toleration and tolerance will also be used in an indiscriminate manner (for Habermas's position see Habermas 2003, 2-3). 3 See Walter Andreas Euler in his paper at the 2015 SIEPM Colloquium Tolerance and Otherness in Medieval Philosophy (http://www.irishphilosophicalsociety.ie/conferences/siepm-colloquium-2015tolerance-and-concepts-of-otherness-in-medieval-philosophy-9-12-september-2015/; last accessed December 11, 2019). 4 Anna Akasoy also rightly identifies the problem that most authors who make a plea for Cusa being tolerant or intolerant do not actually put forward a clear definition of toleration (see Akasoy 2005, 107). As will be shown later, most recent and contemporary research into toleration suggests that we do not talk about toleration in cases where differences are affirmed or embraced.
Thus, even recently, the late scholar Morimichi Watanabe, when stating that "Cusanus's relationship between Christianity and other religions was not based on completely relativistic views on religious tolerance," takes it as a given that tolerance is relativistic and pluralistic (2014,12). Likewise, Aikin and Aleksander assume a "pluralistic tolerance" as the goal of Cusa's work De pace fidei (see Aikin and Jason 2013). These two examples may suffice; however, the same point can be made about the majority of Cusa scholarship. standards as to whether Cusa was tolerant or not, and rather than remaining completely within the historical context of his time, we can establish a clearer understanding of Cusa's reasoning with regard to toleration, thus constructing a deeper and more precise analysis of his toleration of Islam, or lack thereof.
We will, finally, raise the issue that whether Cusa was tolerant or not may in fact have [7] been the wrong question to begin with. Rather than asking the catchall question, 'Was Cusa tolerant of Islam?', we suggest a more refined set of questions that would focus on what level of tolerance we encounter in the different texts of Cusa and what the grounds for acceptance, objection, and rejection were that we can identify. Depending on the text, context, and addressees, answers differ. One would assume that with closer intellectual 'contact,' and the more Cusa identifies Islam as part of the Christian tradition, the more tolerant he would become. However, the opposite seems to be the case: the more Islam is identified as heresy, and thus as what I refer to later as the 'internal Other,' the more the Cardinal rejects the diverging teachings and practices of Islam as he sees it.

Developing the Framework: Toleration as Tertium Comparationis
Against positions that declare that there are many different interpretations of toleration, and [8] following Rawls' distinction between concept and conceptions, Rainer Forst, one of the leading contemporary thinkers on toleration, develops the idea that we can establish "a core meaning, and this core is the concept of toleration" (2013, 17, emphasis in original) in his work Toleration in Conflict: Past and Present. 5 In order to be able to speak of toleration at all, Forst, taking up Preston King's notion of toleration, posits three necessary components: (1) an objection component, without which we would not have the necessity for toleration at all but would actually experience affirmation or indifference; (2) an acceptance component "which specifies that the tolerated convictions and practices are condemned as false or bad, yet not so false or bad that other, positive reasons do not speak for tolerating them" (2013, 20); and finally (3) a rejection component that establishes the reasons for the limits of one's toleration (2013,(17)(18)(19)(20)(21)(22)(23).
Forst rightly indicates that there are thus three different types of reasoning involved in any [9] discussion on toleration: finding reasons for accepting, objecting to, or rejecting a particular belief, practice, etc. All of these reasons may rest on different justifications: moral, pragmatic, religious, etc. Thus, one may have a religious objection to a particular practice, pragmatic reasons for acceptance (and thus tolerating something), and, finally, moral reasons not to tolerate a particular practice, belief, etc. It is these elements that we need to keep in mind foremost when analyzing Cusa's arguments for accepting, objecting to, and rejecting certain Islamic doctrines.
In this way, our concept of toleration functions, much like the Lesbian Rule, 6 as a flexible [10] 5 Anna Akasoy, in her paper "Zur Toleranz gegenüber dem Islam bei Lullus und Cusanus" ("On Tolerance Regarding Islam in Lullus and Cusanus"), also works with Forst's concept of toleration as a tool for analysis. However, rather than concentrating on the three core components of the concept of toleration, Akasoy uses Forst in a different way by making use of six components. This, however, makes it harder to establish the concept of toleration as an 'impartial' tertium comparationis, in my opinion, given that the modern interpretations of toleration potentially come more to the fore (see Akasoy 2005). tool with which to understand and measure toleration in different approaches, independently of their origin and historical context. At this stage already, we can conclude three points: Firstly, the reasons for acceptance, objection, and rejection of a belief, etc., may differ from [11] culture to culture both geographically as well as historically. If the reasons that are deemed to be acceptable depend on cultural and social context, one cannot necessarily even speak of a particular culture, as a whole, as more or less tolerant, as there may be greater toleration (or even acceptance) when it comes to, for example, religious diversity, but less when it comes to, for instance, social norms.
Secondly, we tend to treat toleration as a positive attitude or a virtue, so that intolerance [12] (relying on the rejection component) needs to be thoroughly justified. However, this has not always been the case. Through investigating a number of positions regarding the toleration of otherness, it becomes clear that, for instance, in the debates in the Middle Ages, it was not rejection but acceptance of otherness that often needed to be justified (see, e.g., Aquinas on tolerating others in STh II, II, qu. 10-12). Thus, our position today is a substantial change of perspective from the medieval position, since we tend to argue from the perspective that toleration comes first and that we need to defend it.
Both of the above points lead to the following third observation: not only do we need to look [13] into the different ideas Cusa had on toleration, but also at the epistemological and axiological premises that are seen as binding and which underlie the arguments for toleration or rejection of particular beliefs, practices, etc. (see also Kuçuradi 1996, 168f). This will be taken up in greater detail below.
From the foregoing, we now begin to see with regard to the question of Cusa's understanding [14] of "toleration" that we will need to reformulate the traditional catchall question. As such, asking whether Cusa was tolerant or not in his approach to Islam is a misleading question as it already presupposes a particular understanding of tolerance. Instead, by identifying on what grounds Cusa accepts, objects to, or rejects Islamic doctrines opens up a much more promising approach. 7

Cusa's Stance on Islam
Cusa's engagement with Islam, though not overly extensive, is still outstanding for his time. [15] Walter Andreas Euler, in his article "A Critical Survey on Cusanus's Writings on Islam" (2014), presents a comprehensive overview regarding the writings in which Cusa mainly engaged with Islam. After the Fall of Constantinople in 1453, Cusa wrote his famous work on interreligious 6 Aristotle uses the idea of the Lesbian rule, the leaden rule used in Lesbian building, as a metaphor for the importance of the flexibility (as opposed to the rigidity) of rules and measures with regard to, for instance, equitable justice. Thus, one can have an objective standard which yet remains flexible with regard to different situations (see Aristotle, Nicomachean Ethics, 1137b 29-33). 7 This can be seen in number of positions presented in scholarship. Interpreters often assume a particular concept of toleration, normally one that Forst has summarized under the different conceptions of toleration, such as respect or even esteem (see Forst 2013, 29-31). Phrased differently, and as we pointed out earlier, scholars assume a pluralistic or relativistic idea, i.e., a particular type of enacted political and social toleration as the concept of toleration. Furthermore, toleration comes in a wide variety of forms, from respecting different values although not agreeing with them (which comes closer to our general understanding of toleration) to the position that "[w]hat the tolerant person 'tolerates' is not the radical different views, opinions, norms or attitudes, ways of behaviour, practices, and given actions of the others, but the existence of these others" (Kuçuradi 1996, 165f.). However, as this paper is primarily neither about different forms of toleration nor the connection between rights (to exist) and toleration, this issue does not need to concern us further at this juncture. dialogue, De pace fidei; then followed, in 1454, the letter to Juan de Segovia, and finally the Cribratio Alkorani in 1460/61. As Euler correctly states, there are a number of reasons why we can consider Cusa's interest [16] in Islam to be considerable. Not only does Cusa already state, in the preface of the Cribratio Alkorani, that he had an interest in the Qur'an for a long time; he also, as Biechler pointed out, studied the Qur'an extensively a number of times (see Biechler 1983). 8 Depending on the goal, Cusa's engagement with Islam differs in each of his writings. Euler [17] traces this development by showing Cusanus' growing awareness of the fact that Islam might not be integrated into a Christian interpretation without problems after all (as had still been suggested and thus hoped for by Cusa in his utopian vision outlined in De pace fidei; see Euler 2014, 28-29). Let's trace some of the important points in this development while keeping one last important point in mind: while Cusa's contact with Islam, as far as we can see, remained on a purely theoretical and mediated level (as there seems in all likelihood not to have been any actual encounter or exchange with Islamic scholars and Cusa was confined to the Ketton translation of the Qur'an and the apologetic literature of his time) 9 , the endeavour itself did not. Instead, it was framed by real political, and indeed existential, concerns, given the awareness of an Islamic military power advancing from the East.
De pace fidei, the most famous and influential work of the three, has a very clear irenic [18] stance, aiming at a concordantia between the different religions. Driven by the desire for peace after the fall of Constantinople and the atrocities committed afterwards, this motivation is clearly displayed by the text starting with a man (presumably Cusanus himself, who visited Constantinople in 1437) praying to God to lessen the raging persecution that was a result of the different practices of religion (Nicholas of Cusa [1453] 1989, 706, 710). What follows is well known: using his philosophical ideas of the coincidentia oppositorum and explicatio, Cusa argues that all rites (i.e., different philosophical approaches and religions)-due to the existing diversity in peoples-present the unfolding of 'the one' religion, motivated by the desire of all men for the greater good and for absolute wisdom.
This ontological underpinning, to which we will return in more detail later, is further-[19] more supported by the latent (though here not explicitly named) methodological tool of the manuductio, i.e., to lead the interlocutors by the hand towards the desired understanding, 10 a technique that will appear more explicitly in the Cribratio Alkorani.
The dialogue unfolds in a particular, repeated pattern: agreements are put forward quickly, [20] philosophical leaps in the argument are permitted, and theological Christian presuppositions are often accepted without much questioning. Thus, for example, the Arab agrees with the Word that all men desire wisdom and that everyone presupposes the one absolute wisdom that is God by replying in the following way: "This is it. And no intelligent being could think otherwise" (Nicholas of Cusa [1453] 1989, 724). Likewise, differences, while mentioned by individual interlocutors, either get downplayed, or are already pre-empted by the interlocutors themselves, or are overcome very quickly with the basic Christian dogma emerging as universally acceptable and the most reasonable of all. Thus, for example, the Word's explanation of the Trinity in response to the Chaldean is accepted by the Jew without any further 8 With the finding of another annotated manuscript in Rome, these conclusions can only be confirmed (cf. Martínez Gázquez 2015). 9 On the question whether Cusa had an actual exchange with Muslims, see the recent article by Halff (2019, esp. 50ff). 10 This has been pointed out by a number of scholars (see, for example, Bakos 2011; Biechler 1991Biechler , 2004. questions and with the latter exclaiming: "The above all praised Trinity, that no one can deny has been explained in the best possible manner" (Nicholas of Cusa [1453] 1989, 738). 11 And while not even the version of Christianity practiced at Cusa's time can be identified with [21] the una religio, the basic foundations turn out to be coherent with, and adequately expressed in, Christian dogma (see Euler 2014, 23).
The Letter to Juan de Segovia has a slightly different focus. Here, Cusa also emphasises the [22] importance of dialogue, but at the same time acknowledges that the Trinity is a major problem in discussions with Muslims. This is also true, according to Cusa, regarding questions on Christology or the Eucharist. The letter shows two interesting developments: first, the suggestion to turn the artificial dialogue into a real one by including those Christians who live under Arabic rule and who thus not only have a better understanding and practical experience of Islam but may also be more easily accepted by the Islamic side; 12 and second, the fact that Cusa now acknowledges considerable disagreements with Islam on certain Christian dogmas in a way he did not in De pace fidei. Nevertheless, as Euler points out, "he [Cusanus] remains convinced that the pro-Christian essence of the Qur'an is far more substantial than the conflicting elements, and that a corresponding interpretation of Islam is therefore hermeneutically valid" (Euler 2014, 27).
Finally, the Cribratio Alkorani, a work written to provide Cusa's friend Pope Pius II with [23] a manual for an encounter with Islam, and potentially the conqueror of Constantinople, Mehmed II, 13 takes a different angle again, although the irenic stance is continued, if somewhat muted. Like the letter to Segovia and unlike De pace fidei, the Cribratio is concerned specifically with Islam.
The Cribratio shows itself to be a curious mixture of apologetic, polemic, and inclusive [24] passages. It is perhaps because of this mixture, its "somewhat haphazard" organization, its polemic passages against Mohammed, and that it "does not really advance the philosophical and theological arguments [of De pace fidei and De docta ignorantia]" (Alfsåg 2014, 63) that, with few exceptions (such as Burgevin 1969;Hagemann 1976), the Cribratio had not received the same scholarly attention as De pace fidei. Hagemann remarks regarding its relevance that "the value of the Cusanic work does not show itself first and foremost in its usefulness for today but in its historical relevance" (Hagemann 1976, 183). Likewise, Euler affirms that overall, the work does not offer satisfactory (or useful) responses to the problem of the Christian-Islamic dialogue; however, it nevertheless remains an interesting work as it shows "a deepened awareness of an underlying problem […] the ambivalence of Islam, which displays both pro-and anti-Christian sides" (Euler 2014, 29).
From the perspective of the historical development of the Qur'an and of Islam as a religion, [25] the ambivalent passages as well as the concordances that Cusa spotted, of course, make sense. In addition, the inaccuracies of Cusa's Qur'anic interpretation, or some of his apparently almost violent attempts to read the truths of the Gospel from the Qur'an, are better understood when taking into account the fact that Cusa had to work with Robert of Ketton's translation of the Qur'an, which was completed in the mid-twelfth century, commissioned by Peter the Venerable. Robert of Ketton, however, was not driven by the desire for an accurate literal 11 Optime explenata est superbenedicta trinitas, quae negare nequit. Only in an afterthought is it explained that the Trinity, as the Arabs and the Jews interpret it, should be rejected by everyone (thus implying a severe misunderstanding), while the true Trinity must be accepted by everyone. On the explanation of the Trinity, see chapters VIII and IX of De pace fidei. 12 For the full text, see Klibansky and Bascour (1956). See also Hollmann (2017, 83f.). 13 For the full text, see Nicholas of Cusa ([1460-1461] 1989-1993). translation but rather by the motivation to introduce the Western reader to the content of this 'strange' religion. This hermeneutic approach, which resulted in paraphrasing as well as mistakes in the actual translation, substantially contributed to Cusa's own interpretation of Islam. 14 In any case, what is interesting for our question of toleration is not so much the accuracy of [26] the Qur'an translation and Cusa's awareness of it but how he approached the encounter with Islam in the years after De pace fidei, after further study and further political developments. We can also ask ourselves in how far the increasing awareness of irreconcilable differences with Islam and the more aggressive judgements on Mohammed were a result of Cusa's more detailed knowledge and study.
As Hagemann points out in his Introduction to the Meiner edition, Cusa makes use of three [27] distinct methodological approaches to achieve his goals, not only to inform his contemporaries about Islam but also to build a theological bridge for Muslims: a pia interpretatio as a basis for a benevolent interpretation of Islam; the aforementioned manuductio ad Trinitatem; and, finally, the rationabilitias to demonstrate that what was given in (Christian) faith as reasonable (see Hagemann in Nicholas of Cusa [1460-1461] 1989-1993. 15 The latter deserves some more attention. Hoffmann points out how rationabilitas and ratio-[28] nalitas were widely used in a synonymous manner, even though Augustine emphasised the difference between rationalis as the ability and rationabile as the "product" of this ability, i.e., that it is reasonable (Hoffmann, Rolke, and Gosepath 1992, 52). 16 More specifically, used as a technical term in Canon Law, it refers to the reasonableness of a law that is contrasted with the inhumanity of a law, therefore presupposing a conformity with the principles of Christian morality, fairness, prudence, justice, and honesty. Rationabilitas thus indicates that something is agreeable to human reason but also expresses the harmony that should be between human law and divine law (Di Paolo 2016, 128n35). 17 When Cusa himself uses the term (such as in De coniecturis), he generally seems to do so in conformity with the Augustinian interpretation.
Cusa also follows a long-standing Latin tradition (Tischler 2015) when it comes to his ap-[29] proach to Islam in the Cribratio, where he refers to it not as the religion of Mohammed but as the law of Mohammed (lex Mahummeti). This now allows him to use the concept of rationabilitas as a means to assess Islam in the Cribratio (at least for the most part) as a set of laws from , not only gives an excellent overview of the reception of the translation of Robert of Ketton (including the many critical responses regarding the translation starting as early as Juan de Segovia) and provides the reader with a detailed textual analysis, but also-here mainly referring to Burman-raises the question whether a literal translation was indeed the actual goal of Robert (see Cecini 2012). Burman makes the interesting case that while there is no denying that Robert was an "exuberant paraphraser," he (i.e., Burman) wants to take issue with the position that this is the reason why the translation turns out to be poor and misleading. Burman himself acknowledges that this raises the question of what a good translation is in cases where paraphrasing may be truer to the original than a literal one. While not denying the mistakes and problems of Robert of Ketton's translations, Burman supports his point by showing how Robert's use of several Arabic tafsīr indicates the heavy influence of the Arabic tradition on the Qur'an exegesis (see Burman 1998, 707). 15 Biechler makes the interesting point that Cusa's main goal is to present a convincing argument for those Christians who had converted to Islam (see Biechler 2004, 285). 16 […] rationabile autem, quod ratione factum esset aut dictum (Augustine, De ordine II, 11, 31). 17 Di Paolo also points out that while rationabilitas expressed a general conformity of the teaching of the Christian faith for the Church fathers, it acquired a much more juridical sense for the Medieval canon lawyers after Pope Gregory the Great (see Di Paolo 2016, 128). It would be very interesting to inquire into the question as to how much of Cusa's understanding of rationabilitas is not only informed by Augustine but-with Cusa being a trained canon lawyer himself-the canon law tradition. However, we leave this for another occasion. a moral and prudential point of view (in the widest sense), in terms of conformity with the teachings of the Christian faith. 18 In light of the above observations, the Cribratio can be summarized as follows: the first [30] book of the Cribratio focuses on Cusa's proof that the Qur'an is written by humans and that what is true is true because it agrees with the Gospel; the second book mainly focuses on the manuductiones ad Trinitatem, and the third book essentially contains a-mainly polemiccriticism of Islam.
There is without doubt evidence for all the different interpretations that we have seen over [31] the years of the Cribratio: Hagemann's irenic interpretation (Hagemann in Nicholas of Cusa [1460-1461 1989-1993, 1: X), Hölscher's position that Cusa attempted an interpretation that was as conscientious as possible (Hölscher in Nicholas of Cusa 1946), but also Jaspers' critical assessment of the Cribratio as a work of anti-Islamic polemic and intolerance (Jaspers 1964, esp. 188).
Regarding the question of the development of Cusa's attitude towards Islam, we can observe [32] the following: the evidence of his engagement with Islam and the available sources demonstrates an ongoing interest and desire to understand Islam. However, if I am right in that Cusa, in the first instance, applies the concept of rationabilitas more rigorously, and secondly, favours the classic interpretation of Islam as a heretical Christian sect, this then helps us to better understand the shifts we see in the Cribratio, which are as follows: Cusa's intention is no longer so much concerned with demonstrating how all rites participate in the one religion but to sieve the Qur'an for the truth of the Gospel (a point that connects the Cribratio with Cusa's letter to Juan de Segovia). With the Gospel becoming the emphasised and central point and lens of reference, Islam is now explicitly understood as a heretical sect of Christianity. Deviations are thus judged more strongly on moral grounds than before and are now explained as consequences of the (mainly ill) intentions of Mohammed, leading to the polemics that dominate much of the Cribratio.

Cusa's Engagement with Islam Revisited
Forst, when laying out some key historical positions on toleration, summarizes his perspective [33] on Cusa as follows: Nicolas of Cusa's De Pace Fidei (1453) marks an important step towards a more [34] comprehensive, Christian-humanist conception of toleration, though in the conversations among representatives of different faiths his core idea of "one religion in various rites" remains a Catholic one. Still, the search for common elements is a central, increasingly important topic in toleration discourses (Forst 2017).
This statement is worth expanding upon: toleration, while needing all of the above-[35] 18 Tischler, in his excellent article "'Lex Mahometi' The Authority of a Pattern of Religious Polemics," makes a slightly different point by arguing that by using lex, the medieval authors strengthened the "perspective of comparable religious entities," which is then used as a means to "other" the other religion (2015, 6-7, 11ff.). Interestingly, Tischer also emphasizes the important role of the legal aspect (ibid.). However, I am not sure if, at least in Cusa's case (as in all those who interpret Islam as a Christian heresy), rather than disintegrating and "othering" Islam, it is the case that Islam becomes integrated. Or it might be better to say, as I will develop in my conclusion, that Islam is reinterpreted from the external Other (religion) to the internal, more problematic and even less acceptable Other (heresy). In his approach, Tischler also allows for comparison as leading to integration (2015, 41), but he does not develop this aspect further. mentioned features in order to be considered as such, relies essentially on the acceptance component of those arguments which can trump our reasons for objecting to something. One additional observation is also important: Cusa rests his whole argument not only on the [36] often discussed presumptions of the one truth, which cannot be reached by human thought (which, in turn, is limited by its finiteness). He also assumes two basic presuppositions that are never questioned by him (though they would be today): firstly, the anthropological feature that all humans search for wisdom (based on their having reason and intellect), which is part of the human search for the greater good; secondly, and grounded in the first presupposition, the epistemological assumption that we can assess (and thus judge) all belief systems according to their reasonableness, with the more 'reasonable' one also being 'truer.' 19 Keeping these two principles in mind, we can now turn to Cusa's arguments for acceptance.
[37] There are two arguments, in fact, with one being more fundamental than the other. The first is best expressed in the famous statement una religio in rituum varietate, grounded philosophically, as Alfsåg rightly points out, in the philosophical positions of the De docta ignorantia and the coincidentia oppositorum (see Alfsåg 2014, esp. 60). 20 However, this statement also assumes that this one religion still coincides with the basic doctrines of Catholic Christianity. This is true even when one agrees, as I would, with Aikin's and Aleksander's observation that "Nicholas maintains that an ideal Christianity […] [is,] metaphysically speaking, the only religion, and all of the diverse, finite rites of mundane religions (including his own Catholicism) must be measured according to this ideal universal religion" (Aikin and Jason 2013, 223).
This foundation is most evident and inclusive in De pace fidei. Rather than concluding, [38] however, that this is an indication for a pluralist perspective (as Aikin and Aleksander do), I hold that we see Cusa arguing from, and for, an inclusivist perspective, i.e., what is true in Islam (as well as other religious and philosophical approaches) is true because it is compatible with the essential Catholic Christian dogma on which consensus can be achieved; evidence of this has already been presented earlier. Here, as we have also seen, the distinctions between the different religions or philosophies are marginalised to such an extent that they lose their significance almost completely. Despite Cusa tolerating diversity to a certain degree, this kind of position does not sit well even with an attempted pluralistic approach (as Aikin and Aleksander argue Cusa holds), as pluralism in all its different shapes relies, essentially and in itself, on certain conditions; for example, in the case of "value pluralism" that there is a plurality of values that are incommensurable with one another and, most importantly, cannot be traced back to one 'reference point.' 21 It thus seems to me that it is important to distinguish between embracing plurality and pluralism 22 and that Cusa accepted the former (on ontological grounds) but not the latter.
The second reason for tolerating objectionable positions, such as circumcision or differences [39] in prayer (see Nicholas of Cusa [1453] 1989, 3: cap. XVI, XIX), is the argument for peace and the hope that in accepting that all rites are an expression of the one religio, not only will peace prevail but also will the practices themselves become more magnificent, because the nations 19 This assumption again has to be seen within the context of the concept of rationabilitas. 20 Hagemann has made the interesting observation that Cusa could also see this assumption to be grounded in Islamic doctrine rather than neo-platonic principles. However, there is no reason to treat this question to have an either-or answer, as Cusa could have seen the different sources just as an affirmation that the truth is expressed in many different ways, thus affirming his position. 21 On value pluralism, see Berlin (1969) and Berlin (1953). Of course, it is also important that pluralism does not, as Berlin had pointed out, equal relativism; but since my argument is that Cusa was not attempting pluralism, this point does not need to be developed any further. 22 On the distinction between plurality and pluralism, see Ratzinger (2005, 67).
will try to outshine each other in their adoration for God (Nicholas of Cusa [1453] 1989, 3: 796). In this way, despite the differences, De pace fidei gains an almost Lessing-like quality in the end; 23 or, as de la Cruz Palma and Álvarez Gómez put it: "Cusa aims at a first consensus in a universal faith that is grounded in the love (dilectio) of the one unique God". It is the acknowledgment that the main religions (if not all, as the authors state) participate in the truth; thus, truth becomes the main foundation for toleration (de la Cruz Palma and Álvarez Gómez 2009, 95). 24 The above reasons, easy to trace (and the main focus of much of the scholarship on the [40] topic), now need to be supplemented with the grounds for objection and rejection, which are often analysed less. Since a discussion of toleration, as mentioned above, is also always a discussion of its limits, they will add another dimension to Cusa's approach to diversity.
The grounds for rejection are identified by Cusa without much additional explanation. In [41] response to the question posed by the Indian in chapter VII of De pace fidei as to what should be done with regard to statues and images, the Word replies that those images that further the true cult of the one God are accepted, but not those that lead away from it. Those will justly be destroyed because they deceive and deflect from the truth: tunc quia deciperunt et a veritate avertunt, merito confringo debent (Nicholas of Cusa [1453] 1989. After all, as has repeatedly been pointed out, the work is called De pace fidei, not De pace religionis. Thus, beliefs and rites that endanger faith in the one God are not tolerated but to be rejected. This leads to the question about the "objection component," and here lies the heart of [42] Cusa's approach to difference in De pace fidei. As I aim to show, the answer to this particular question is not as clear-cut and relies substantially on the status of difference in, or diversity of, rites. As we have seen above, what we can say for sure is that difference is not tolerated if it endangers the belief in the one God. However, is a difference in rites objectionable as such? As I have argued elsewhere, Cusa's ontological approach can be used as a basis to appreciate diversity (Gottlöber 2013).
Yet, things may not be that simple after all. If we focus, for the moment, on De pace fidei, [43] we can see the following: in Chapter I, diversity is seen as a fact of created existence. Many peoples came into existence out of the one man and this great multitude is not possible without diversity (see Nicholas of Cusa [1453Cusa [ ] 1989. 25 As such, this diversity, as a fact of human existence, does not seem to be the object of either a positive evaluation or an objection. Thus, the attitude to natural diversity is indifference. 26 However, this natural diversity also leads to a diversity of rites, which becomes problematic when the different rites, born out of long-standing habits and perceived as having become part of nature, are mistaken for truth (see Nicholas of Cusa [1453Cusa [ ] 1989 truth. 27 If this is true, then the diversity in rites is actually not seen as a positive fact to be embraced but rather as something to be endured-tolerated-for the sake of peace as long as the grounds for rejection (leading away from faith in the one God) are not met. This becomes very clear towards the end of the dialogue, where Paulus responds to the question of the Englishman, namely, what to do with the different rites in terms of sacraments, marriage, etc., with, "one has to accommodate as much as possible the weakness of humanity if it does not violate eternal salvation. Demanding an exact conformity would disturb peace" (Nicholas of Cusa [1453Cusa [ ] 1989. 28 Only then it is stated, seeing something positive, as it were, that competition in rites may also lead to a greater and more glorious praise of God. We thus find not one, but three ways of dealing with diversity in De pace fidei: 1. It is [45] accepted as part of natural human existence, but in a rather indifferent way; 2. it is tolerated for the sake of peace as long as, 3., it does not lead away from belief in the one God and endanger salvation. If that is the case, it is to be rejected. That diversity is tolerated as long as belief in the one God is not challenged also enables us [46] to establish a hierarchy on the grounds for acceptance: while peace is the prime motivation for the dialogue (which is also true for the other writings on Islam), backed up by the assumption that most established religions and philosophies participate in the one truth, this argument is subordinated under the basic principles as mentioned above. All differences are to be assessed in this way.
One final point regarding Mohammed deserves mentioning before we turn our attention to [47] the Cribratio: Cusa's position in De pace fidei towards Mohammed is clearly guided by a benign interpretation. Thus, for example, the sensual descriptions of paradise in the Qur'an are interpreted as similes and used to guide an unrefined, uncultured people (rudis populus) away from idolatry (Nicholas of Cusa [1453] 1989, 774). While nowadays this condescending attitude would, in all likelihood, hinder a dialogue rather than advance it, the benign, latitudinarian, and benevolent interpretation that Hagemann and Glei note as the attitude in the Cribratio (Hagemann in Nicholas of Cusa [1460-1461 1989-1993, 1: X) is clearly recognizable in De pace fidei.
In this way, then, we can see that the distance between De pace fidei and the Cribratio [48] Alkorani may not be as great as some scholars would hold. Instead, we see a particular development with, as Euler rightly points out, the inclusivist attitude remaining, even if it becomes less pronounced, as the differences keep coming to the fore more strongly. This becomes most evident in the Cribratio Alkorani, which shall be our final object of focus.
As mentioned earlier, unlike De pace fidei, the Cribratio is focused solely on Islam. Something [49] which is not as conspicuous in De pace fidei now becomes very much a central focus point: For Cusanus, Islam is not only a different rite of the one religion as it is depicted in De pace fidei but is a heretical version of Christianity. 27 In his paper "Zur Bewältigung religiöser Differenz bei Raimundus Lullus und Nikolaus Cusanus" ("On Overcoming Religious Difference in Raimundus Lullus and Nikolaus Cusanus"), Riedenauer gives a slightly different weight to the individual causes of both diversity and potentially resulting violence. Diversity is caused by the multiplication of the first man, there being no immediate relationship to the Deus absconditus and thus a need for mediation through religion; and finally, the universal conditions of human existence living in a world of constant change and imprecision, which necessarily leads to a hermeneutic variability of human language and cognition. These again can lead to violence through misunderstanding the prophets; wrongly identifying habits with the one truth; envy with regard to salvation and fear of losing one's identity; and, finally, the seducible nature of man and the abuse of freedom. Riedenauer thus rightly concludes that Cusa sees the conditio humana in an ambivalent manner (Riedenauer 2005, 95f.). 28 Oportet infirmitati hominum plerumque condescendere, nisi vergat contra aeternam salutem. Nam exactam quaerere conformitatem in omnibus est potius pacem turbare.
The grounds for acceptance largely remain the same, as do the underlying anthropological [50] principles that all men desire wisdom and the greater good (which is identified with God), as well as the Augustinian/neo-Platonic principle that our spirit only rests when it returns to its origin (see Nicholas of Cusa [1460-1461] 1989-1993, 1:6-9). However, now Cusanus explicitly states that his goal is to prove the truth of the Gospel as being present in the Qur'an (see Nicholas of Cusa [1460-1461] 1989-1993, 1:6-9), 29 thus aligning the existing Catholic Christian dogma more closely with the one religion as he did in De pace fidei.
Unlike De pace fidei, most divergences of the Qur'an from the Gospel are no longer inter-[51] preted in a benign manner but, based on the interpretation of Islam as a heresy, used as arguments for rejection. The prologue already asserts "this sect of Mohammed which is a Nestorian heresy is to be condemned" (Nicholas of Cusa [1460-1461] 1989-1993, 1:1). Furthermore, Cusa seems to accept the dominating ideas regarding heresy, as we find, for instance, in Aquinas (cf. again, STh II, II, qu. 12), namely that heresy is grounded in bad intentions. 30 Thus, it is clear for Cusa that where the Qur'an differs from the Gospel this is due-with exceptions-to the evil intention of Mohammed (ex perversitate intenti Mahumeti). This bad intention stems, like all evil, from ignorance, a fact that Cusa sees as proven (Nicholas of Cusa [1460-1461] 1989-1993, 1:12). The intended "sieving of the Qur'an" will thus separate the truth from lies and in this way also educate the Muslims (Nicholas of Cusa [1460-1461] 1989-1993, 1:12).
However, while large parts of the Cribratio follow this intention as laid out in the beginning, [52] resulting in the curious mixture, already mentioned above, of polemic attacks and apologetic passages, on closer examination things are not that simple. Even in the Cribratio, not all differences are grounds for rejection. Thus, certain passages indicate a toleration of difference, and it is in these passages that Cusa returns to the lines of thought of his De pace fidei. 31 First of all, the Nestorian influence, as represented mainly by the monk Sergius, 32 is not [53] seen in a purely negative light. Thus, Cusa states that Sergius himself attempted to reconcile apostates (whom he refers to as "brothers of that sect" (fratres […] illius sectae, Nicholas of Cusa [1460-1461] 1989-1993, 1:14) and pagans with Christianity in Mecca and attributes an overall positive influence of Sergius over Mohammed. Cusa acknowledges where the Nestorians (and thus also Mohammed) agree with the accepted dogma, and even when he points out mistakes in the Nestorian interpretation, he does so without the condemning overtone that he takes in later passages against the Qur'an. 33 Therefore, some (not further specified) differences seem tolerable, as they are used to guide people back to the true faith. This is a similar argument to that which we have seen in De pace fidei. It is also employed, again mirroring De pace fidei, when Cusa states in the second book of the Cribratio that, according 29 […] ut etiam ex Alkorano evangelium verum ostenderem. 30 Although there were positions that understood heresy as not intentionally erroneous but that heretic beliefs could also stem from a sincere rejection of the  (Leff 1967, 1; see also Borst 1974Borst , esp. 1000 It is these passages that lead Kuhn-Emmerich to her assessment that the main passages in the Cribratio stand in concordance with De pace fidei (Kuhn-Emmerich 1968, 139f). 32 The assumption, which is a firm constant in the Christian polemic against Islam, is that the Nestorian monk Sergius influenced Mohammed. This is based in the Islamic Bahīrā story (see Hagemann in Nicholas of Cusa [1460-1461] 1989-1993:XI-XII). 33 For example, he just uses the verb erravit without any further judgment (see Nicholas of Cusa [1460-1461] 1989-1993, 1: 16). He also accuses "three sly Jews" of being responsible for not becoming fully Christian and including passages in the Qur'an after Mohammed's death (see Nicholas of Cusa [1460-1461] 1989-1993, 1:14).
to his benign interpretation, Mohammed could reveal certain mysteries only to the educated Arabs (Nicholas of Cusa [1460-1461] 1989-1993, 2:34). Finally, again in the first book of the Cribratio, Cusa refers to the fact that while observing the identity of the faith, it cannot be seen as obstructive to adhere to different rites (Nicholas of Cusa [1460-1461] 1989-1993, 3:37). 34 These passages seem to contradict the statement in the beginning of the prologue, where all difference is attributed to Mohammed's bad will and ignorance. However, these passages are rarer and the Cribratio is certainly dominated by Cusa's apologetic attempts (which include 'proving' the erroneous positions in the Qur'an, accompanied by polemic passages) to convince Muslims to give up their religion and to convert. It becomes clear in De pace fidei, and maybe even more so in the Cribratio (as well as in Cusa's [54] letter to Juan de Segovia), that Cusa's goal is not toleration itself but a peaceful encounter between the different religions, with one being a distortion of the other, yet entailing the truth of the Gospel. The latter foundation for acceptance (and thus toleration), while still detectable, has become smaller, with differences becoming more pronounced and, due what is now regarded as the 'bad intention' of a misguided and mistaken Mohammed, are seen as grounds for rejection.
This leads to a final observation that at this stage is not much more than a hunch but [55] might prove fruitful for further investigation. There often seems to be a greater intolerance towards what I would call the 'internal Other' (that can be identified according to different parameters, such as religious difference, gender, etc.) than the 'external Other.' The attitudes towards heretics, also taken up by Cusa, are just one historical example. If this is true then we may conclude-though still carefully at this stage-that in identifying Islam as a heretic sect, Cusa becomes more intolerant of its differences.

Conclusion
The goal of this paper has been to analyse Cusa's intellectual encounter with Islam as a case [56] study in the use of toleration. The approach used a minimal understanding of toleration as a tertium comparationis in a manner that did not judge Cusa's approach according to modern, value-laden conceptions of toleration.
As we saw, focusing mainly on De pace fidei and Cribratio Alkorani, despite their differences [57] these works have a number of points in common. Firstly, none of them actually acknowledges that the differences form an essential part of the self-understanding and identity of the other. Secondly, the irenic position that Cusa displays in all three works (if we include the letter to Juan de Segovia) remains a central theme. And finally, Cusa's use of rationabilitas remains central to his approach.
Any kind of attempted understanding of toleration arises out of one's own, and thus a [58] contemporary, perspective. Thus, I would argue that relating a position from a historically different context to one's own is-like any comparison-beneficial for a clarification of both positions, one's own as well as the other. 35 It may, in addition, be helpful to understand the different stances scholarship has taken over the years to judge Cusa's position regarding 34 In toleration, while at the same time, if one wishes, taking Cusa as a reference point in history, to 'think with Cusa beyond Cusa,' although this was not the task of the present analysis. Those scholars who establish that Cusa's position is not a position of tolerance seem to do [59] so mainly because they interpret toleration in the sense it is commonly understood today, namely, solely as appreciation of the other. Building on this assumption, they can then identify Cusa's approach as a hidden intolerance of otherness. And indeed, in times when plurality and pluralism have become endowed with intrinsic value, an argument reducing difference to sameness is not deemed acceptable by many, and with good reason. Yet, Kuçuradi makes the point that "it appears that what the tolerant person 'respects' is not 'differences', but what is identical in all human beings", i.e., their humanness, and thus rejecting damage to their rights (Kuçuradi 1996, 166). 36 Cusa's reference point, in a similar fashion, is what is identical, although he does not only appeal to a sameness of human nature but also to one true religio.
This brings us to the second point. While in this time of secularism in the West the attention [60] has very much shifted away from religious truth (to the first duty of being a responsible citizen and observing citizen rights), the argument for peace as a pragmatic argument remains, even though it is expanded to include issues such as human rights. This shift signifies an important transformation of the foundation of the argument for toleration itself. Religious questions (together with many questions of, e.g., moral philosophy concerning the good life) have been moved into the private sphere, with the acknowledgment that many doctrines remain in conflict "and indeed incommensurable" with each other and may not be subject to public reason at all (Rawls 1987, 4). This is clearly an unacceptable (and maybe even an unthinkable) position for Cusanus. Today, we thus see a general acceptance not only of values but also of an epistemological pluralism grounded in the belief that not all areas of life are governed by the same concept of 'truth.' But as peace (and, closely connected, the right not to suffer, at least physically) and the basic rights protecting the individual seem to be universally accepted values that benefit all, they have now become the dominating reference points. Thinking along those lines, Aikin and Aleksander equally conclude: "We, on the other hand, suspect that it is preferable to provide a political justification for religious concord than it is to provide a theological justification for peaceful politics" (Aikin and Jason 2013, 234).
The perhaps most surprising conclusion, in my opinion, is related to the third point. There is, [61] of course, a long-standing tradition that the major foundations of Western civilisation, such as human rights and human dignity, are grounded in Christian thought, with prominent thinkers such as Habermas as representatives. We also, of course, see a similar argument of grounding the emphasis on reason in the Western intellectual tradition in Greek philosophy. The truth or falseness of these claims does not concern us here. However, we may, I argue, add the concept of rationabilitas to those foundations. One may contend that Cusa's approach only made sense within the context of the rationabilitas arguments of the Middle Ages, in terms of what is generally accepted as agreed foundations (such as epistemological or axiological assumptions or assumptions regarding human nature). However, with revealed truths, or indeed 'truth' per se no longer being the generally accepted reference point, one may think that the relevance of the concept of rationabilitas has declined as well.
Yet it seems to me that we do not just use rationality as central means to discern the intol-[62] erable. Rather, what we see even with the shift of the arguments from truth to rights, equal 36 Berlin's argument that pluralism is not relativism and one can be a pluralist even when rejecting certain positions follows a similar line. citizenship, etc. is an appeal to the agreeableness, on moral and juridical grounds, to human rights and human dignity, which are now regarded as having universal value. 37 This would mean that we still operate with the concept of rationabilitas, but have changed our reference points from divine law to secularised versions of human dignity and human rights, thus secularising the idea of rationabilitas as well. Still, the fundamental feature of rationabilitas, namely the belief that we can argue for the judgement that certain beliefs, practices, etc. are, or should be, in concordance (or not) with, for instance, human rights, stays the same. Thus, the intolerable positions of our time, such as religious extremism, right wing conservatism, racism, sexism, etc., are now judged along those lines. This secularization comes at a price: deprived of its religious source, the concept has be-[63] come fragile, if not necessarily incoherent. This does not mean that one needs to go back to foundations of absolute certainty, as is argued especially from conservative positions. Rather, the fragility of the concept calls for constantly discerning its intellectual and intuitive roots, while at the same time recognizing the limits of these foundations rather than taking them for granted. In this way, the awareness that 'it could be otherwise' becomes integrated into the concept itself.
How tolerable, then, is Cusa's tolerance? It is here, in our final reflections, that we turn to [64] the question of the intolerable. As noted throughout the concluding remarks, our axiological foundations have shifted profoundly, and with it what we define as acceptable, objectionable, and rejectable. As Kuçuradi rightly pointed out, while it is not possible to develop positive criteria to define the tolerable, it is possible to formulate these criteria for the intolerable (Kuçuradi 1996, 169-70). Using a secularised version of rationabilitas to discern the intolerable, we now no longer reject those positions that endanger the faith in the one God, but those that violate human rights, damage human dignity, and harm, in general, human flourishing (Kuçuradi 1996, 168). 38 Insisting on religious truth has in itself come under suspicion of underlying intolerable acts (and many examples, historical and recent, can be cited to support this view), even though Cusa's position in De pace fidei is a good example that this does not need to be the case if one accepts that one's rites (to return to Cusa's expression) are not identical with the one truth. In this way, by creating a broader justification for acceptance, and thus toleration, of difference in religious rites, Cusa provided the seeds for later arguments for a pluralistic approach. Toleration of difference becomes an intermediate stage and a step towards a later affirmation of plurality as something intrinsically valuable.
One final remark: while the notion of what 'the greater good' is and what constitutes human [65] flourishing has-thankfully-diversified, we still agree with Cusa that violence, for one, is harmful to it. Additional basic values like freedom of expression, equality, etc. have been added. We thus still have underlying notions of what constitutes the foundations of 'the greater good' for humans and human societies that need protecting. These foundations are no less valid if they don't have an 'absolute foundation' any longer; it just means they have become more fragile and need constant care, deliberation, validation, and possibly (re)evaluation. It is here that thinking about toleration has a role to play. Like in Cusa's time, properly understood toleration is not just a " 'flimsy' [concept in the] meaning of 'let everyone think and say what they want, and I am not interested in anyone as long as they are not bothering me' " (Decorte 37 See, for example, Habermas, Kucuradi, Ricoeur, and Rawls (Habermas 2003;Kuçuradi 1996;Ricoeur 1996;Rawls 1987). One can potentially make a similar argument for scientific knowledge taking a similar place, though for the sake of the argument of toleration we will remain within the 'practical' context for the moment. Anti-evolution theories, for example, would be judged along those lines. 38 See also Ricoeur (1996, 169-70), who refers explicitly to the principle of harm.
2004, 115). Rather, through thinking about toleration we use toleration as a means to identify the intolerable which, then as now, is what harms human flourishing.