When Orthodox Rabbi Avi Shafran and Conservative Rabbi Jerome Epstein publicly debated halakhic authority, they revealed a striking shift in modern American Judaism: religious movements now define themselves primarily against other Jewish denominations rather than external cultures. Through the lens of Franz Rosenzweig's 1923 essay "Apologetic Thinking," analysis of the rabbis' published arguments exposes fundamental flaws in both Orthodox and Conservative apologetic discourse. Shafran's triumphalist stance fails to acknowledge Orthodox inconsistencies, while Epstein's defensive rhetoric inadequately articulates Conservative Judaism's core principles. Textual analysis and philosophical examination demonstrate that while apologetic thinking has historically driven Jewish creativity and self-definition, contemporary practitioners often default to either excessive defensiveness or false triumphalism, missing vital opportunities for constructive self-examination. Effective apologetic discourse in American Judaism requires acknowledging both universal and particular dimensions of Jewish identity, while recognizing the limitations of one's position and engaging seriously with alternative Jewish expressions. These dynamics illuminate how Jewish movements navigate questions of authority and authenticity within America's unprecedented religious pluralism.