Moses Maimonides was the first medieval Jewish thinker to posit a set of dogmas for Judaism. These are his 'Thirteen Principles of Faith'. Maimonides' statement initiated an extensive discussion among other medieval Jewish thinkers on the subject of dogma, which had an important impact on subsequent Jewish thought. This reaction to Maimonides' innovation was complex: some scholars accepted his position without reservation; other accepted the idea that Jewish beliefs could be reduced to a creed but disagreed with Maimonides' specific formulation of that creed; still others rejected the project of creed formulation in Judaism altogether. The locus classicus of this last position is the Rosh Amanah of Isaac Abranavel (1437-1508). Abravanel's ostensible aim in writing Rosh Amanah was to defend Maimonides' creed from the attacks of its critics, notably Hasdai Crescas and Joseph Albo, and it contains the most exhaustive and systematic analysis of the thirteen principles ever written. After twenty-two chapters of sustained and zealous defence of Maimonides, however, Abravanel seems to contradict himself and argues at the end of his book that in fact Judaism has no dogmas whatsoever, since all its beliefs are equally valid, fundamental, and precious. This is the first complete English translation of Abravanel's classic work, and includes a comprehensive introduction and notes.