Locke on the Idea of Substratum

Locke's treatment of substratum is notoriously difficult. Accordingto one commentator, 'nothing else in the writings of any philosopher matches the doubleness of attitude of the passages about substratum in Locke's Essay' (Bennett 1987, 197). The aim of the present paper is to render consistent Locke's seemingly divergent strands on the subject. My efforts are organized around three levels of apparent duplicity. At each level, I argue that the doubleness of attitude in Locke's treatment is merely apparent. I argue further that Locke means to ground an empiricist-friendly idea of substratum in the customary experience of simple ideas that 'go constantly together.'