Stephen Eric Bronner, a Rutgers University political scientist whose family escaped for Hitler's Germany, traces the history of "Protocols" in his slender new book. "A Rumor About the Jews" is cleanly written, and the charged emotions that have marred many assessments of "Protocols" are blessedly absent. But the book has little else to recommend it. Bronner's suggestion that "Protocols" married anti-Semitism with a larger attack on Enlightenment thinking can be found in most Western Civ textbooks. And his digressive assertion, in the concluding pages, that "anti-Semitism is no longer a threat in the terms of times past" is no more innovative.