The problem of how we can know the existence and nature of the world external to our mind is one of the oldest and most difficult in philosophy. The discussion by John Locke (1632-1704) of knowledge of the external world have proved to be some of the most confusing and difficult passages of his entire body of philosophical work.

John Locke s An Essay Concerning Human Understanding begins with a clear statement of an epistemological goal: to explain the limits of human knowledge, opinion, and ignorance. The actual text of the Essay, in stark contrast, takes a long and seemingly meandering path before returning to that goal at the Essay s end one with many detours through questions in philosophy of mind, metaphysics, and philosophy of language. Over time, Locke scholarship has come to focus on Locke s contributions to (...) these parts of philosophy. In Locke s Science of Knowledge, Priselac refocuses on the Essay s epistemological thread, arguing that the Essay is unified from beginning to end around its compositional theory of ideas and the active role Locke gives the mind in constructing its thoughts. To support the plausibility and demonstrate the value of this interpretation, Priselac argues that contrary to its reputation as being at best sloppy and at worst outright inconsistent Locke s discussion of skepticism and account of knowledge of the external world fits neatly within the Essay s epistemology. ". (shrink)

It is here argued that Locke and Newton held very similar views on the nature of our knowledge of substance: our only cognitive access to substances is through their powers to affect our minds and other substances. However, in spite of this shared empiricist foundation, Locke and Newton held divergent views on the unification of powers or qualities into a single substance. While Locke allows that distinct powers can be understood as united in one substance (indeed all substances are collections (...) of powers for Locke), this paper argues for an interpretation of Newton according to which substance cannot have distinct powers. Rather, a substance just is a power in space and time. (shrink)