Who is a Jew? Evolve Essay Summary By Mordecai M. Kaplan From the diaries of Rabbi Mordecai M. Kaplan, a reflection on how to define the term “Jew.” This is a summary of an essay available in the "Identity" section of Evolve: Groundbreaking Jewish Conversations. Click here to read the full essay. Click here for a categorized listing of all essays from Evolve: Groundbreaking Conversations.