In the Essay Concerning Human Understanding, Locke insists that all knowledge consists in perception of the agreement or disagreement of ideas. However, he also insists that knowledge extends to outer reality, claiming that perception yields ‘sensitive knowledge’ of the existence of outer objects. Some scholars have argued that Locke did not really mean to restrict knowledge to perceptions of relations within the realm of ideas; others have argued that sensitive knowledge is not strictly speaking a form of knowledge for Locke. (...) This chapter argues that Locke’s conception of sensitive knowledge is in fact compatible with his official definition of knowledge, and discusses his treatment of the problem of skepticism, both in the Essay and in the correspondence with Stillingfleet. (shrink)