Introduction

This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. This chapter examines a variety of different issues that have arisen in connection with the notions of substance employed by Locke and Leibniz and the role that these notions play in their understanding of other issues that have been the focus of recent scholarly debates. Samuel C. Rickless argues that some of the best reasons for thinking that Locke considers persons to be modes, particularly those offered recently by Antonia LoLordo, are not compelling. Leibniz's causal theory has proved difficult to determine and some of his comments and have been taken to suggest positions that threaten to collapse back into occasionalism or mere conservationism. Locke and Leibniz about substance illustrate both the centrality and the difficulty of that concept to philosophy, and specifically to philosophers of the early modern period.