 We said that Shepherd mentions at the beginning of her second book that there might seem to be circularity in her procedure (EASP: Preface). The earlier volume argues for the causal principles and maintains that they regulate all speculative and practical belief. The second essay uses these principles to explain the origin of belief in the existence of the external world, and then claims this belief is justified. This might seem to be circular, as if the assumption that the causal principles have instances in the world were used to prove the existence of the external world which was taken to prove the assumption. But Shepherd maintains her procedure is not circular. She explains that the “justness” of these beliefs could not be fully established before it was shown that all sensations whatsoever are believed to be successive effects of various causes: 