Recent research in Jewish cultural history, following post-modernist or situational perspectives, has voiced strong objections against any essential definition of Jewishness. In Judaism, with its characteristic absence of a central authority, religious and cultural norms indeed presented themselves often as matters of choice inside a grid of internal divisions. The present class will approach Jewish history from the point of view of its fragmentation into conflicting groups (variously named as parties, sects, movements, denominations, or sub-ethnicities) and study the dynamics of opposition and coexistence in different historical periods. Students will learn to problematize generalizations about Jewish identity, but also observe that the different „Judaisms“ (a plural introduced by Jacob Neusner) hardly ever produced formal schisms: while strongly resenting and rejecting each other’s convictions, the parties ultimately recognize each other as competing partners in a common collective destiny that would be incomplete without the internal adversary. In a popular joke, the Jewish Robinson Crusoe builds two synagogues on his lone island: he prays in the one and piously avoids the other.