Stony Brook University

is the virtue moderated by right reason.
Justice is the charity of the wise, or what is congruent with the judgment
of the good and prudent person; or it is the virtue of the affection of one
person toward another, that is, the benevolence as well as the aversion,
moderated and directed by right reason. 19
Justice is of course defined here as charity of the wise, and this charity is said to be
congruent with the judgment of the good and prudent person; thus the notion of the “wise
person” comes to absorb the earlier notions of the good and prudent person (vir bonus
and prudens). But it is important to keep in mind that justice is always a virtue, as clearly
indicated here. It is the virtue involving right relations with others (as Aristotle says),
which for Leibniz means the virtue of charity or benevolence toward others. Most
important is that justice is the virtue moderated by right reason. Now, Leibniz does not
explain what he means by right reason, but the meaning is certainly close to Aristotle’s
orthos logos. 20 The Elementa had offered some explanation of ‘right reason’ in very
similar terms, where justice was defined as the virtue of moderating the affections, such
that “nothing may be able to oppose the commands of right reason.” Furthermore, “the
right reason for an action is the same as prudence,” as it is precisely for Aristotle. 21 The
purpose in the Elementa was to show that prudence (conceived as one’s own good) and
justice are compatible. 22 However, that formulation does not really tell us what right
reason is other than prudence, and so we are going around in a circle.
To escape this circle it becomes clear in “On Justice and Right” that right reason
means whatever directs the conservation and perfection of society. Furthermore, this
points to the object of right itself. To see this we must follow the text step by step.
Leibniz next defines the terms justum and jus, then borrows some additional notions from
the Digest, and then shows that the three degrees correspond to right reason. To continue
from where we left off:
19 A.6.4.2777: “Justitia est caritas sapientis, seu quae boni prudentisque viri arbitrio congruit; sive est virtus
affectum hominis erga hominem, benevolentiam scilicet atque odium, moderans ac dirigens secundum
rectam rationem.”
20 Beeley (1997) claims that Leibniz’s conception of right reason underwent a change. Up to the early ‘70’s
Leibniz had an Aristotelian subjective notion of right reason (orthos logos) related to prudence. (See
Aristotle AE Bk 6, 13, 1144b22-7: “when they define virtue, after naming it the state of character and its
objects add ‘that state which is in accordance with the right rule’; now the right rule is that which is in
accordance with prudence (practical wisdom, phronesis). But Leibniz also identified right reason with a
stoic, objective law likened to the “eternal truths” of mathematics, a view he adopted in later works, as we
will see.
21 A.6.1.461: “Justitia sit omnium consensu virtus qvaedam, virtus autem omnis ea affectuum frenatio, ut
nihil obsistere rationis rectae imperiis possint, Ratio autem recta agendorum cum prudentia idem sit,
conseqvens est, nec justitiam sine prudentia esse posse.” AE 1144b23: thn kata ton orqon logon; orqos d
o kata thn fronhsin.
22 Leibniz also had rejected right reason as a definition of the just, since then the definition would wrongly
include errors (non-intentional actions) as unjust. But this rejection showed only that right reason is too
broad to define the just, and is rejected as part of his effort to show that the nature of justice is love.
Therefore, this rejection should not count as a rejection of right reason itself. It is important to keep in mind
a statement Leibniz made in a letter to Magnus Wedderkopf (1671), in a discussion on freedom and
necessity: “For it is the highest freedom to be impelled to the best by a right reason” (LL 147 / A.2.1.186):
“Quod Summa enim libertas est ad optimum a recta ratione cogi, qui aliam libertatem desiderat stultus est.”
108