Stony Brook University

Preface
This dissertation examines a neglected area of Leibniz’s philosophy, namely, his
theory of right (jus). Contrary to prevailing views, I argue that his theory, much of which
is established in his earliest writings, is the foundation of his practical philosophy as a
whole. In contemporary terms, Leibniz’s conception of right may be called “subjective
right,” rooted in the Grotian tradition; but it is also informed by a variety of historical
sources, most dominantly Aristotle and Roman Law. In general, we can understand
Leibniz’s theory to be motivated by two main concerns: (1) to establish the moral
limitations on power, whether natural, political, or divine power; (2) to reconcile utilitas
(conceived as the good for oneself) with honestas (conceived as the good for others). The
resolution to these concerns, I argue, lies in Leibniz’s a priori “science” of right.
A key feature of this science is Leibniz’s demonstrative method, which consists of
the analysis of definitions and the derivation of precepts. I show, according to Leibniz’s
definitions, that the science of right is constructed in the following way: right (jus) and
obligation are the moral qualities of a rational substance (substantia rationalis). In other
words, right is the moral power (potentia moralis) and obligation is the moral necessity
of a person to perform and to demand what is just. On this deontic basis Leibniz
“derives” additional founding principles: the three precepts of right (harm no one, give to
each his due, and live honorably); the just condition (the common good); the definition of
the good person (one who loves everyone); and justice defined as a virtue (ultimately as
“the charity of the wise”). Thus, the concepts of right and obligation denote the deontic
moral properties of an agent enabling her to act according to an objectively just order. On
the most basic level, subjective right is the self-limiting, self-determining, capacity of a
moral agent. On the broadest level subjective right implies moral perfection or virtue, and
partly constitutes the freedom of rational beings. While Leibniz’s practical philosophy
undergoes certain developments, this foundation of right as a moral power remains
essential. Notably, Leibniz had established this foundation well-before his earliest
conception of monadic substance.
Most treatments of Leibniz’s practical philosophy focus on the requirements of
pleasure, happiness, love, divine retribution, metaphysical perfection, or on the
compatibility of divine free will with divine creation of an optimum world. Most
commentators hold that Leibniz’s theory of right (often subsumed under the more general
category of “natural law”) derives from these central and overarching metaphysical
premises, or, that his early formulations are superseded and sufficiently summarized by
his mature definition of justice as “charity of the wise” (caritas sapientis). However, I
argue that the derivation is exactly reversed: these central metaphysical premises, along
with caritas sapientis, depend on his science of right as their normative foundation.
This reversal of ground and consequent in Leibniz’s practical philosophy requires
understanding the logical connection between the moral qualities (right and obligation)
and the precepts of right. It also requires carefully distinguishing the meanings of right
(jus), just (justum) and justice (justitia) as a virtue. Furthermore, Leibniz’s attempt to
reconcile utilitas and honestas leads him to find “disinterested love” essential to justice,
and this appears to lead him to fundamentally hedonist grounds for practical philosophy. I