Han-Kyul Kim

In the Essay, Locke refers to the ordinary-sized natural things as ‘particular sorts of Substances’ (2.23), whereas the ‘three sorts of Substances’ (2.27) are more metaphysically laden sorts: God, finite spirits, and fundamental material particles. He posits the much-contested ‘substratum’ in each particular sort of substance but not any of the three sorts. It should also be noted that his list of the particular sorts includes ‘men’. In regard to this nobler sort, he refers to a further classification – viz., ‘the Substance of spirit’ and ‘the Substance of the body’ – only in terms of their nominal essence. A naturalistic, nominalist approach is deeply entrenched in his account of the human-related sorts as well. In this chapter, I shall explore how Locke develops a theory of substance in the Essay that is less metaphysical, more naturalistic, and epistemically humbler than those of his rationalist contemporaries.

The world is occupied by many and varied things. What constitutes their thingness? In the Essay, Locke addresses this question in Book II, Chapter xxiii, titled ‘Of our Complex Ideas of Substance’, wherein the much-contested definition of ‘substratum’ appears—‘a supposed but unknown support of the Qualities’. Most significant in this definition are the dual qualifiers that Locke uses: ‘supposed’ and ‘unknown’. This paper examines this two-qualifier definition, illuminating the historical and philosophical significance it may have. There have been two rival readings. The first takes Locke’s substratum to be a bare substratum; and the second identifies it with what Locke terms as ‘real essence’—i.e. ‘a real Constitution of the insensible Parts’. Critically reviewing these two major interpretations, I attribute to Locke a type of functionalism, according to which the status of a substratum is determined by its functional role of ‘uniting’ a bundle of qualities into an individual substance.

From the Lockean point of view, the mind-body problem is conceived as a problem created by us. It is an error to think there is a problem with mind and body, an error of confusing nominality with reality. I argue that Locke’s agnosticism should be understood as a warning not to confuse our human point of view with what really is. From this perspective, the mind-body problem is a nominal problem, not a real one. It appears to us as a problem, but is not really so. But what makes it appear to us as a problem? This is Locke’s starting point for solving the mind-body problem.

The wide range of conflicting interpretations that exist in regard to Locke's philosophy of mind and body (i.e. dualistic, materialist, idealistic) can be explained by the general failure of commentators to appreciate the full extent of his nominalism. Although his nominalism that focuses on specific natural kinds has been much discussed, his mind-body nominalism remains largely neglected. This neglect, I shall argue, has given rise to the current diversity of interpretations. This paper offers a solution to this interpretative puzzle, and it attributes a view to Locke that I shall describe as nominal symmetry.

The wide range of conflicting interpretations that exist in regard to Locke's philosophy of mind and body (i.e. dualistic, materialist, idealistic) can be explained by the general failure of commentators to appreciate the full extent of his nominalism. Although his nominalism that focuses on specific natural kinds has been much discussed, his mind-body nominalism remains largely neglected. This neglect, I shall argue, has given rise to the current diversity of interpretations. This paper offers a solution to this interpretative puzzle, and it attributes a view to Locke that I shall describe as nominal symmetry

In this paper, I address the controversial issue around Locke’s account of a “superadded” power of thought. I first show that Locke uses the term “super­addition” in discussing the nominal distinction of natural kinds. This general observation applies to Locke’s account of thinking matter. Specifically, I attribute to him the following three theses: (1) the mind-body distinction is nominal; (2) there is no metaphysical repugnancy between them; and (3) their common ground—namely, substratum—can only be characterized in terms of its functional role. Examining each thesis and their interconnections, this paper casts light upon the Lockean type of mind-body union in “a system of matter fitly disposed.”

It has often been claimed that Locke’s agnostic remarks in the Essay represent his suspension of philosophical judgment on crucial ontological issues or his hesitation over which metaphysical stance to adopt. Against this often-raised criticism, I argue that Locke actually held a clear position—a type of functionalism about thingness in general, whether macro or micro, or whether mental or physical. What Locke refers to as a ‘nominal essence’, I further argue, represents a set of functional roles that a thing plays in order to be classified as of a kind to which it belongs. Our empirical knowledge about things—confined to their nominal essences—can only tell us about their functional roles but not their intrinsic properties that realize those roles. One remains therefore incurably ignorant about the intrinsic property of things in themselves. I explore the historical and philosophical significance of Locke’s functional approach.

This book begins with a survey of various readings of Locke as a materialist, as a substance dualist, and as a property dualist, and demonstrates that these inconsistent interpretations result from a general failure of modern commentators to notice the significance of Locke’s ‘mind-body nominalism’. By illuminating this largely overlooked aspect of Locke’s philosophy, this book reveals a common mistake of previous interpretations: that of treating what Locke conceives to be ‘nominal’ as real. The nominal symmetry that Locke posits between mind and body is distinct from any form of metaphysical dualism, whether substance dualism or property dualism. It is a brand of naturalism, but does not insist that the material is ontologically more basic than the mental or that the former determines the latter. On this view, the material and the mental both relate solely to a certain set of functional roles, rather than to an intrinsic property that plays these roles. The term ‘matter’ is thus rendered vague, and materialism is conceived as a precariously grounded ontological doctrine. Elaborating on this interpretation of Locke’s Essay, this book examines the insightful readings of Locke developed by seventeenth- and eighteenth-century thinkers such as Richard Burthogge, William Carroll, and Joseph Priestley. This book also seeks to clarify what Locke’s position would look like in a modern setting by noting some significant parallels with the ideas of leading contemporary philosophers such as Donald Davidson, David Lewis, and Colin McGinn.