340 A History of Judaism
propositions, principles and reason, even though he claimed that (for
instance) authority for the existence of God must be attributed only to
the Bible. For Crescas, like Maimonides primarily a communal leader
and close to the ruling powers of the time, Aristotelianism was danger-
ous because it had been used by Jewish intellectuals to justify deserting
Judaism. It is of course ironic that Crescas’ own polemic showed an
intimate knowledge of the tradition he attacked. His attacks on Aris-
totle’s philosophy should be seen alongside his Refutation of the Principles
of the Christians, published in Catalan in 1397– 8, which contained a
fiercely logical critique of major Christian doctrines such as original sin,
the Trinity, incarnation and the virgin birth in an effort to win back Jew-
ish apostates to Christianity.^38
A similar impulse to respond to the threat of Christianity lay behind
the Book of Principles of Crescas’ pupil Yosef Albo. Albo was one of the
spokesmen for the Jews in a very public and protracted forced disput-
ation in Tortosa from January 1413 to April 1414, as a result of which
many Jews converted to Christianity, encouraged undoubtedly also by
memories of the communal violence suffered by the Jews of Aragon in
1391 during which the son of Crescas himself had been a victim of mur-
der. Albo’s book, with its focus on law as the basis of salvation, contains
an implicit anti- Christian message in the relegation of belief in a mes-
siah to a level below that of a principle in Judaism. According to Albo,
a failure to believe that a messiah would come might be a sin but it
would not constitute heresy. Albo knew the works of Christian scholas-
tics such as Thomas Aquinas, and in disputes with Christians he was
acutely aware of the weaknesses of Maimonides’ formulation of thir-
teen principles of faith, including the hope in a future messiah. Crescas
had proposed a shorter list of six principles, which Albo in turn whittled
down to three: the existence of God, divine revelation, and reward and
punishment. It is ironic that this list of three principles, which Albo
probably borrowed from his older contemporary Shimon b. Tsemach
Duran (who taught in Algiers after an anti- Jewish outbreak in his native
Majorca in 1391), was taken originally from the Islamic Aristotelian
Averroes, who had asserted that anyone denying any one of these prin-
ciples is an unbeliever in Islam. Albo’s Book of Principles was to be
immensely popular in later generations, helped by the availability of a
printed edition from 1485.^39
By the fifteenth century a philosophical approach to religious ideas
had thus come to seem natural to many Jews, even while the balance of
authority between reason and revelation remained a constant point of