Modern psychology, it is widely held, was born as a “science of mental life” based almost exclusively on the method of introspection. The most salient example is E.B. Titchener’s influential system of psychology known as “introspectionism.” Early in the twentieth century, this approach fell into disfavor—and, in turn, introspection as such also came to be seen as a dead end in psychology. As this paper argues, Titchener’s psychology was based on the key notions of elementism, reductionism and sensationism. His philosophical commitment to these suppositions was deep and the general aim was to deliver a comprehensive scientific account of human mental life in accordance with that pre-experimental, theoretical agenda. The scientific goal of introspectionism was thus not to describe mental phenomena as they naturally and plainly form part of the subject’s experience. Here, Titchener’s approach contrasts rather starkly with contemporary introspective approaches, such as Descriptive Experience Sampling, that aim to bracket assumptions and theory. In sum, this paper calls into question the assumption that introspectionism in psychology should be regarded as an archetypal instantiation in the history of science, of a psychological system built on a fundamental commitment to introspection.