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Averroism in Iberia: Yitzhak Baer, Álvaro Pelayo and Questions about Jewishness

Thomas Hendrik Kaal, Queen Mary University of London

Zusammenfassung: Die erzwungene Konversionsbewegung von iberischen Juden im Jahr 1391 wirft nach wie vor viele Fragen auf. Warum konnten so viele Sephardim dazu gebracht werden, ihrem ererbten Glauben zu entsagen und Christen zu werden? Für Yitzhak Baer lag der Schlüssel zu dieser Frage in der Verbreitung des sogenannten Averroismus. Seine Ansicht nach hatte rationalistische Philosophie die religiösen Überzeugungen derart unterminiert, dass insbesondere die gebildeten Juden nicht mehr bereit waren, Vertreibung oder den Märtyrertod zu erdulden. Baers Hypothese ist bereits aus unterschiedlichen Perspektiven kritisiert wurden. Dieser Artikel eröffnet eine neue Sichtweise auf die Thematik, in dem er den Blick auf Averroismus in christlichen Quellen richtet. Den Ausgangspunkt der Überlegungen bildet das häresiologische Kompendium Collyrium fidei des Franziskaners Álvaro Pelayo.

Abstract: The forced mass conversion of Iberian Jews in 1391 continues to raise numerous questions. Why could so many Sephardim be brought to renounce their inherited faith and become Christians? Yitzhak Baer believed that the key to answering this question lay in the spread of Averroistic philosophy among the Sephardim. In his view, rationalist philosophy had so deeply undermined the religious faith of many Iberian Jews, particularly of the more educated, that they were no longer willing to endure expulsion or martyrdom. Baer’s interpretation of Averroism has been criticized from various perspectives. This article proposes a new approach to the subject, shifting the focus to the representation of Averroism in Christian sources, with the heresiological compendium Collyrium fidei by Franciscan friar Álvaro Pelayo serving as a starting point for further reflections.

In his famous study History of the Jews in Christian Spain, the German-Israeli historian Yitzhak Baer (1888–1980) suggested that Spanish Jewry in the Late Middle Ages was deeply influenced by a philosophical current known as “Averroism”.1 This tradition, named after Ibn Rushd (1126–1198), is said to be most notably characterized by the belief that religion and philosophy are entirely separate, enabling them to arrive at different conclusions without contradicting or undermining one another.2 Baer argued that this split between the realm of knowledge and the realm of faith weakened the Jewish community in Iberia, making them more vulnerable to conversionary pressure. For if one could no longer determine beyond reasonable doubt that Judaism was true, and Christianity false, then there was significantly less incentive for a Jew to remain faithful to his or her inherited religion. When many Jews at the end of the 14th century were confronted with the choice of either converting to Christianity or dying the death of a Jewish martyr, those affected by Averroism simply could not muster the strength to remain faithful to their religion but converted to Christianity in large numbers. Baer thus argued that Averroism was the key factor behind the mass conversions of Jews in Spain in 1391.3 Based on his thesis, Averroism has become a recurring theme in the academic debate about the converts and their numerous descendants, the so-called conversos. It is used to explain the deviant religiosity, unbelief and skepticism among the New Christians, which can be found in 15th-century sources, especially in inquisition records.4

Scholars have long criticized Baer’s thesis for lacking sufficient evidence.5 A Jewish convert who explicitly invoked Averroism as a justification for the pragmatic acceptance of Christianity has yet to be identified. While Baer cited the works of Jewish anti-philosophers to support his claims, Daniel J. Lasker demonstrated decades ago that the tenets of Averroism did not prevent authors from maintaining their belief in the rational superiority of Judaism. It was entirely possible to be both “an Averroistic philosopher and a loyal Jew”.6 So, considering the inner Jewish debate, the evidence for Baer’s thesis appears rather thin. But what about Christian sources? Baer suggested that Christian guardians of orthodoxy feared a rationalist undermining of their faith through the corrosive influence of Averroism in the guise of Jewish converts. The persecution of conversos by the Spanish Inquisition, therefore, appears to be a response to the realization that many of them were but “philosophical intellectuals, Averroists, and nihilists”.7 This raises the possibility of finding indications of the spread of Jewish Averroism in contemporary Christian sources. Yet, the representation of Jewish Averroism in Christian sources from the Iberian Peninsula has not yet been studied in depth. This article is part of an ongoing research project, offering a few initial observations drawn from a heresiological compendium titled Collyrium fidei by friar Álvaro Pelayo (1280–1350).

Collyrium fidei is a peculiar text. It shows Álvaro Pelayo as a particularly unforbearing persecutor of religious deviance.8 In Book V, Álvaro condemns the heresy of a certain Thomas Scotus, an intellectual Averroist par excellence: Thomas reportedly argued that the world should be governed by philosophy rather than religious laws. He held that Judaism, Islam, and Christianity were sinister machinations of three impostors—Moses, Jesus, and Mohammed. He rejected the virgin birth, did not believe in angels, demons, the sacraments, creation ex nihilo, or any notion of an afterlife. Thomas also thought that all miracles were either false or could be fully explained by natural processes.9 To modern readers, this may sound like the description of a skeptical, ‘enlightened’ intellectual. But this was not how Álvaro understood the position of his opponent. Rather, he was visibly concerned to connect Thomas’ Averroistic position with Judaism. The friar went to great lengths to argue that Thomas was, in fact, a Judaizer.

What can Collyrium fidei tell us about the perception of Averroism in late medieval Iberia? First, we learn that zealous friars like Álvaro Pelayo were definitely concerned about the detrimental impact of Averroistic philosophy. Secondly, Collyrium fidei evidences a strong discursive connection between Averroism and Judaism. However, it seems that this connection existed more in Álvaro’s mind than in reality. For the friar, any form of unbelief and questioning of Christian truth claims was automatically akin to Judaism. Judaism functioned as a hermeneutical lens through which Christian authors could recognize and condemn unwanted tendencies in society and even in their own thinking.10 Considering that Collyrium fidei was already written decades before the mass conversion of 1391, we can see it did not take a mass influx of Averroistic conversions, as envisaged by Baer, to establish a closeness between heterodox Aristotelianism and Judaizing in Christian Iberian heresiology. The idea that Spanish Inquisitors in the late 15th century out of the blue ‘discovered’ a connection between Judaizing conversos and Averroism is clearly mistaken. This observation calls us to further investigate the discursive identification of heterodox philosophical ideas with Judaism in contemporary Christian discourses, especially with regards to the so-called converso problem—the growing concern about the New Christian population in Iberia that ultimately led to the Spanish Inquisition. In doing so, one discovers that some of the essentialist notions of Jewishness evident in medieval sources continue to shape the scholarly debate on conversos, in Yitzhak Baer’s time as well as today.


Photo: Andrea di Bonaiuto, Triumph of St. Thomas and Allegory of the Sciences, 1365–1368, fresco, Cappella Spagnuola, Santa Maria Novella, Florence, in; Wikimedia Commons, URL: [https://creativecommons.org/licenses/by/3.0] (20.08.2024).

  1. Yitzhak Baer, A History of the Jews in Christian Spain (Philadelphia: Jewish Publication Society of America, 1961), I, 240, 263, 290 and II, 52, 137–138, 253–259. []
  2. This distinction is usually inferred from Averroes’ Kitab Fasl al-Maqal. On his attempt to reconcile the claims of reason with the demands of faith, see Diego R. Sarrió, ‘The Philosopher as the Heir of the Prophets. Averroes’s Islamic Rationalism’, Al-Qanṭara, 36 (2015), 45–68. []
  3. Baer, A History of the Jews, 138: “Apart from material considerations, it was the Averroist outlook that in the main prompted the better educated Jews to choose the easiest way. […] Those individuals who habitually looked down upon the simple masses who scrupulously observed all the commandments, these same men, when the test came, lacked the spiritual fortitude to prefer death to apostasy. In much the same spirit as they had previously denied the authority of biblical law, they now accepted the rites and ceremonies of an alien religion; ultimately, they only remained faithful to their ‘religion of the intellect’.” []
  4. See, among others, See Francisco Márquez Villanueva, ‘El caso del averroísmo popular español (hacia la Celestina)’, in José Luis Canet Vallés and Rafael Beltrán Llavador (eds.), Cinco siglos de “Celestina”. Aportaciones interpretativas (Valencia, 1997) and Yirmiyahu Yovel, The Other Within: The Marranos: Split Identity and Emerging Modernity (Princeton: Princeton University Press, 2009), 44–5. []
  5. See, for example, Norman Roth, Conversos, Inquisition, and the Expulsion of the Jews from Spain (Madison: University of Wisconsin Press, 1995), 61–5. []
  6. Daniel J. Lasker, ‘Averroistic Trends in Jewish-Christian Polemics in the Late Middle Ages’, Speculum, 55 (1980), 304. []
  7. Baer, A History of the Jews, II, 224, 274. []
  8. Álvaro Pelayo, Collyrium fidei, ed. and trans. by Miguel Pinto de Meneses, Lisbon 1954–1956. []
  9. For a summary of the accusations against Thomas see Michele de Araújo, Tradição e poder no colírio da fé: um estudo sobre heresiologia política medieval (Brasilia: University of Brasilia, 2015), 69–70. []
  10. David Nirenberg, ‘Enmity and Assimilation’, Common Knowledge, 9 (2003), 151. []