This is a review of Roger Woolhouse's biography of Locke.

Locke usually uses the term “judgment” in a rather narrow but not unusual sense, as referring to the faculty that produces probable opinion or assent.2 His account is explicitly developed in analogy with knowledge, and like knowledge, it is developed in terms of the relation various ideas bear to one another. Whereas knowledge is the perception of the agreement or disagreement of any of our ideas, judgment is the presumption of their agreement or disagreement. Intuitive knowledge is the immediate perception (...) of the agreement or disagreement of two ideas, e.g., white is not black. If we perceive the idea of white, and the idea of black, nothing more is needed to perceive that white and black disagree with respect to identity. We just see or intuit it. Demonstrative knowledge is more complicated. Suppose we have or perceive the idea of the internal angles of a triangle, and also the idea of two right angles. Unless one is a prodigy, we can’t just “see” that these two ideas agree with respect to equality; we require a demonstration. For Locke, such a demonstration requires that we find another idea, such as 180 degrees, so that we can intuit that this idea stands in the relation of equality both to the internal angles of a triangle, and to two right angles. Thus a demonstration, for Locke, is a chain of ideas. (shrink)

The primary aim of this essay is to explain the central elements of Locke's theory of knowledge. A secondary aim arises from the official definition of knowledge introduced in the opening lines of book IV. Though Locke's repeated statements of the definition are consistent with the initial formulation, the consensus view among commentators is that that official definition is in tension with other book IV doctrines. My broader interpretation involves an effort to render the various doctrines consistent with the official (...) definition. The order of discussion: Section 1 explicates the definition of knowledge. Section 2 explains two main divisions of knowledge – namely, its three degrees, and the four sorts of knowable truths. In Section 3, I consider whether Locke understands knowable truths on a model of analyticity. Section 4 addresses potential problems about the objectivity of knowledge, given Locke's account. Section 5 focuses on external world knowledge – Locke calls this "sensitive knowledge" and it poses special difficulties for the official definition of knowledge. (shrink)