Stony Brook University

an account of virtue. This shows, once again, that the descriptive principles Leibniz
insists on ultimately depend on the normative prescriptions of right and reason.
Chapter 6 examined two shorter late works, the Méditation sur la notion
commune de la justice (1703) and Monita quaedam ad Principia Pufendorfii (1706).
Drawing from both texts I show that the “science of right” depends on the divine ideas
and precepts of right, namely, equality, proportion, and the “rule of reason,” i.e.,
Leibniz’s unique version of the Golden Rule. In addition, I show that the logical
properties of the Rule (equality and equity) conform to the first two precepts of right.
Thus I claim that the Rule is the “formal reason” of justice Leibniz seeks in the
Meditation. On this basis I claim that Leibniz’s ultimate definition of justice as “charity
of the wise” is grounded in his science of right. Also on this basis Leibniz substantially
attacks the voluntarism of Hobbes and Pufendorf. Since their accounts of obligation and
justice are grounded in the will and power of a superior coercive force, justice is rendered
arbitrary and incoherent. For Leibniz, natural, legislative, and divine power must be
regulated by a moral power, a power expressing love and reason, and whose theoretical
foundation lies in the a priori science of right.
However, Leibniz’s infusion of pleasure into his account of the virtue of justice
threatens to undermine this purely rational foundation. Yet when pleasure is properly
understood in Stoic terms as the result of virtue, but not as the end of virtue, then we
understand that the virtue of justice is the highest good. Leibniz’s practical philosophy
can be characterized as a perfectionist virtue ethics built upon deontic notions of right and
obligation. For Leibniz this makes utilitas consistent with honestas. The source of right is
and must be internal virtue following right reason, rather than external compulsions.
Chapter 7 concludes the dissertation by comparing Leibniz’s notions of “moral
necessity” in the early Nova Methodus with the “moral necessity" as developed in late
texts such as Theodicy. One commentator in particular argues that the early and late
notions are distinct. However, I argue that they are not, since they both refer to the
obligation that a rational being has to perform the moral good. I also suggest that moral
necessity, as the self-limitation of a rational being, holds implications for the doctrine of
freedom that Leibniz develops in Theodicy. The degree to which a person determines
herself according to moral principles is the degree to which she exercises free will.
It might be thought that the distinction between metaphysical and moral necessity
is a consequence of Leibniz’s propositional logic. That is, the distinction is required in
order to account for the sufficient reason of truths. Necessary propositions are true by
virtue of the principles of identity and non-contradiction; but these principles do not
apply to contingent truths, so they need a sufficient reason. God is then brought in as the
cause that makes contingent propositions true. However, there is another way to look at
this. Rather than conceiving of the matter as a difficulty within logic, it should be clear
that the difficulty is a matter of the proper grounds of morals. Leibniz’s practical
philosophy does not derive from the requirements of logic, but rather the logic derives
from the requirement that this world be a world of moral value. This requirement is met
when necessity is conceived as the necessary correlate to potentia moralis.
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