Abstract
According to Berkeley, then, the unconscious process of inference of the scientist goes as follows. He notices that, when he does not have his house within visual range, he cannot see it just by wishing to; and that, when he does have it within visual range and his eyes open, he cannot prevent himself from seeing it just by wishing not to. He therefore infers that he is not the efficient cause of these sensations. But, since he holds that they must have some efficient cause, he concludes that this is a congeries of "material substances," which are numerically distinct and partly dissimilar from the sensations, and which exist even when unperceived, or "externally to the mind." As a psychological theory, this seems to be at any rate plausible.