This chapter covers the rise of ethical Noncognitivism in the form of emotivism. After a brief introduction to the main claims of emotivism, emotivism is situated in the broader context of twentieth-century thought. This is essential since the verificationist perspective which supplied the official rationale for emotivism was wildly implausible, and its appeal is intelligible only if we understand it in the context of the Modern drive toward scientific knowledge. As the criteria for counting as “scientific” were made narrower and more precise, they seemed to exclude the possibility of moral knowledge. At the time, this could easily have been taken as a reductio of scientism (since of course there must be moral knowledge!), but emotivism emerged as a way of saving radical empiricism from refutation in the face of presumed moral knowledge. The bulk of Chapter 4 is taken up with detailed critical analyses of the emotivist views of A. J. Ayer, C. L. Stevenson, and Hans Reichenbach.