This important new study of rabbinic boundary formation and increasing self-perception as a group in distinction from other Jews is the revised version of a doctoral dissertation supervised by Peter Schäfer and submitted to Princeton University in 2014. The author suggests replacing the former ‘over-reliance on the idea of “heresy” as an overarching analytical category’ (p. 220) with a focus on the rhetorical devices used to distinguish rabbis from those outside the rabbinic movement in rabbinic texts from the tannaitic period to the Babylonian Talmud. He presents a detailed historical-critical study of literary terms used by rabbis to construct rhetorical boundaries around themselves to establish their own group identity. Rather than reckoning with the establishment of ‘rabbinic Judaism’ immediately after 70 ce or in competition with Christianity in the third or fourth century ce, he emphasises the gradual emergence of rabbinic self-consciousness: ‘the formation of a unified rabbinic self-conception was a process that occurred only gradually and unevenly over this entire period’ (p. 6). Rabbinic self-formation finds its full expression only in the edited version of the Babylonian Talmud, associated with the sixth century, while Palestinian and Babylonian amoraic texts indicate preliminary steps taken into that direction. What is important is that ‘boundary rhetoric and community formation are intrinsically related’ (p. 217). Due to the developing nature of this process, concepts such as ‘rabbinic community’ and ‘rabbinic Judaism’ should be considered ‘heuristic approximations’ (p. 218) for diverse and complex phenomena rather than descriptions of a reality that already existed fully-formed in the first centuries ce.

The seven chapters of this study focus on the terms minim, ‘sinners of Israel’, meshummadim and apiqorsim and on individuals such as Elisha b. Abuya, used as polemical targets and means of rabbinic self-definition. The texts in which these terms and individuals are mentioned are categorised as ‘boundary rhetoric’ and traced from tannaitic and amoraic traditions to the edited stage of the Babylonian Talmud. While earlier studies tended to apply the Christian concept of ‘heresy’ to an allegedly developing rabbinic ‘orthodoxy’, Grossberg rejects this approach as ‘oversimplified and potentially anachronistic’ (p. 3). We lack any evidence about the actual existence and identity of these categories of Jews. In the texts they appear as mere straw figures or bogeymen that allow rabbis to distinguish themselves from other Jews. In contrast to early Christian literature, the term ‘heresy’ never appears in rabbinic texts. Even if a certain definition of ‘heresy’ is used, the search for such a phenomenon in rabbinic texts may lead to circular arguments: ‘It is clear, therefore, that the ancient concept of heresy as such is part of an early Christian polemical lexicon that does not shed much light on developments in rabbinic polemics’ (p. 41). One wonders, however, why this inappropriate term nevertheless appears in the title of the book, without quotation marks.

Grossberg identifies a chronological development in the rabbinic use of the term minim. While the term may have originally referred to an unknown pre-70 Jewish ‘sect’ (in M. Yad. 4:8 a min is debating with a Pharisee), by the fourth century the minim had become ‘a shadowy and threatening hybrid’ (p. 74) associated with a variety of practices and beliefs that rabbis rejected, such as the belief in ‘two powers in heaven’. The eventual conflation between minim and non-Jewish Christians, that is, outsiders not only of the rabbinic movement but of Jewish society at large, appears in the Babylonian Talmud only. By the sixth century minim had become the ‘stock non-Jewish opponent for rabbinic disputation’ (p. 88). Grossberg focuses on the minim’s associations with ‘dangerous ideas about God’ (p. 86) rather than examining the min, matrona and philosopher as exchangeable categories in stories about encounters with rabbis. One wonders whether the hypothesis of such a neat development from non-rabbinic Jew to non-Jew is persuasive in view of the diversity of associations and contexts in amoraic texts. Grossman is aware of the term's broad meaning and rhetorical use. If rabbinic opponents are not clearly demarcated, though, this lack of clarity would point to blurred boundaries and varied and diverse attempts at boundary definition rather than the emergence of a clearly demarcated rabbinic identity.

This leads us to the question of who actually formulated the texts and used the terminology to distinguish himself – or rabbis as a plurality – from ‘others’. Are those who condemn minim, meshummadim and apiqorsim individuals or (sub-)groups of rabbis, tradents or editors? If the ‘we’ are as undefinable and diverse as the ‘they’, at least as far as amoraic traditions are concerned, should we not assume that it was only the edited versions of the Talmuds that created the impression of a somewhat united rabbinic subset within late-antique Jewish society? Grossberg assumes that the ‘evolution’ in the use of this terminology coincided with the rabbinic movement's ‘sense of itself as a collective tasked with establishing a set of universal teachings whose jurisdiction extends implicitly and by necessity over all Jews’ (p. 143). Even the Babylonian Talmud fails to replace the internal rabbinic diversity with ‘universal teachings’ agreed upon by all rabbis, however, so that neither an ‘orthodoxy’ nor an ‘orthopraxy’ emerged. What Grossberg shows is that rabbinic self-distinction from others was not linked to specific halakhic views and ‘correct’ beliefs. It should rather be seen as constantly shifting, imprecise and rhetorical rather than real. Accordingly, the meshummadim and apiqorsim were empty categories whose criticism, exclusion or inclusion did not define rabbinic Judaism content-wise. The categories merely served rabbis to distinguish themselves rhetorically from hypothetical non-rabbis, ‘failed rabbis’ and others within late antique Jewish society. Toward the end of his study Grossberg points out correctly that the next step would be to look at terminology used to refer to rabbis as a collectivity in rabbinic documents to arrive at a clearer sense of the ‘we’.

Although readers may disagree with some of the interpretations and the writing is slightly repetitive, this book can be recommended highly to scholars and students of ancient Judaism and Christianity in general and rabbinic literature in particular.