Locke: Skepticism

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)

The standard objection to Locke’s epistemology is that his conception of knowledge inevitably leads to skepticism about external objects. One reason for this complaint is that Locke defines knowledge as the perception of a relation between ideas, but perceiving relations between ideas does not seem like the kind of thing that can give us knowledge that tables and chairs exist. Thus Locke’s general definition of knowledge seems to be woefully inadequate for explaining knowledge of external objects. However, this interpretation and (...) subsequent criticism ignore a special category of knowledge Locke calls “real knowledge”, which is Locke’s own account of how we can have knowledge of the real world. In in this paper I argue that real knowledge of substances requires that, in addition to the perception of a relation between ideas, there be a necessary connection between our ideas and the external objects they represent. It is because Locke thinks there is a necessary connection between these ideas and reality that he thinks the perception of ideas can give us knowledge of the actual world. (shrink)

In this paper I argue that Locke takes sensitive knowledge (i.e. knowledge from sensation) to be genuine knowledge that material objects exist. Samuel Rickless has recently argued that, for Locke, sensitive knowledge is merely an “assurance”, or a highly probable judgment that falls short of certainty. In reply, I show that Locke sometimes uses “assurance” to describe certain knowledge, and so the use of the term “assurance” to describe sensitive knowledge does not entail that it is less than certain. Further, (...) I show that sensitive knowledge includes the perception of a relation between ideas, and thus it satisfies Locke’s definition of knowledge. He also repeatedly claims that sensitive knowledge is certain. So, despite recent challenges to this interpretation raised in the secondary literature, Locke really does take sensitive knowledge to be certain knowledge. (shrink)