Locke on People and Substances

Abstract

In the famous chapter on identity in the Essay (II.xxvii), Locke notoriously denies that sameness of substance is either necessary or sufficient for sameness of person. In thus denying that the identity of a person is determined by ‘unity of substance’, Locke denies that a person is a substance. If people were substances of some kind, then for me to be the same person through a stretch a time would just be for me to continue to be the same substance of that sort. And yet through most of the Essay the term ‘substance’ is used in a comprehensive contrast with ‘mode’ and ‘relation’: this is, roughly speaking, the trichotomy of thing, property, and relation. If Locke were thinking of substance in this way in the ‘Identity’ chapter, he ought to find it obvious that people are substances, that people are squarely on the substance side of the great divide that has substances (things, beings) on one side of it, and modes and relations on the other. Indeed, he not only ought to find it obvious; he does. At the very outset of the treatment of personal identity he writes: To find wherein personal Identity consists, we must consider what Person stands for; which, I think, is a thinking intelligent Being, that has reason and reflection, and can consider it self as it self, the same thinking thing in different times and places (sec. 9; 335:9).1 Surely a thinking intelligent being belongs on the list of those items that have properties and stand in relations to things, rather than on the list of properties and relations. And since a person is the same item in different times and places, it passes another standard requirement for substancehood. Thinking of a person in this way, how can Locke suppose that one and the same person can ‘involve’ different substances, and vice versa? Here is a further compounding of the puzzle. Two sections before the passage just quoted, Locke is setting up that passage by stating a methodological point: To conceive, and judge of it [identity] aright, we must consider what Idea the Word it is applied to stands for: It being one thing to be the same Substance, another the same Man, and a third the same Person, if Person, Man, and Substance, are three Names standing for three different Ideas; for such as is the Idea belonging to that Name, such must be the Identity (sec. 7; 332:24).