Scientists have no difficulty defining their disciplines by subject matter and methodology, but humanists, however much they agree on the subject matter of the humanities, have no consensus about methodology. In the twentieth century truce resulting from the assumption that there can be no coexistence between the two, scientists and humanists are content to be treated as separate but equal, while social scientists claim to be scientists when it suits their purpose. Humanists produce knowledge without benefit of laboratories, sometimes working like scientists, but their medium is the word, and analogies, striking examples, and logic are their nonscientific proofs. These are the rhetoricians, applying Aristotle's devices as a methodology for discovering proofs about questions that empirical sciences cannot handle: physics can explain how to build a nuclear reactor, but not whether the reactor should be built. The implications of the limits of science on composition research are that limiting study to only quantitative research or developing unrealistic expectations about what quantitative research can deliver would ignore the mainstream of insight in rhetorical theory from Aristotle's time to today. (HTH)