Stony Brook University

To see how this passage implies prudence, we can understand it this way: The just here
means a relation with others, such that one’s desires and reasons for action are those
which another person would either accept or reject. The form of acceptance and rejection
is taken by reward and punishment: when our desires are harmless, they are accepted and
we are rewarded; when they are harmful, they are rejected and we are punished. Thus, the
just depends greatly on how others would respond to us in the form of rewards and
punishments. This is where prudence comes in: to judge matters correctly, we need to
know how others would respond to us in this way; and this knowledge is simply
prudence. Now we can see how justice is prudence. Since justice is a state of the mind or
soul (animus), to do what is just, it must be the state of knowledge about how to act
justly, that is, the state of mind of dealing in rewards and punishments. As Leibniz puts it:
“So that therefore Justice is prudence, for which we do not harm others because of the
penalty and we help them because of the reward.” 19 Also,
Generally: Justice is the prudence in bringing about the other’s good (or
not his evil); and by declaring this intention to bring about one’s own good
(or not one’s evil) that is, an award to attain or a punishment to avoid. 20
With this definition we have arrived at justice as prudence, as the practical knowledge
and desire to attain one’s own good. This turn to prudence however does not prove
definitionally fruitful. Reward and punishment are then defined by pleasure and pain; and
these in turn are defined as “Good” and “Evil,” bringing Leibniz to recognize that “we
are going around in a circle.” 21
Clearly, Leibniz is defining justice in terms of Aristotelian prudence (phronesis),
although arguably more ego–centered and retributively-based. 22 This is, however, only a
step along the way. Leibniz does not intend to define justice as prudence, but rather to
defeat the Carneadean problem by showing that justice is consistent with prudence; thus
not folly. He further intends to move away from the implied egoism by defining justice as
a virtue of the mean, and eventually, in Draft 3, as the virtue of friendship. This
development passes through several stages, beginning with a new set of definitions (on
art, science, knowledge, opinion, wisdom, etc.) appearing at the end of Draft 2. We can
focus on the following:
Prudence is the judiciousness about what is good and bad.
Virtue is the readiness to act well.
19
A.6.1.435: “Ut ergo tandem Iustitia sit prudentia, qva non nocemus aliis poenae, prosumus praemii
causa.”
20
A.6.1 435: “Generaliter: Iustitia est prudentia in efficiendo aliorum bono aut non efficiendo malo boni
sui hac animi declaratione efficiendi, aut mali sui non efficiendi (id est praemii asseqvendi aut poenae
vitandae) causa.”
21
A. 6.1.435: “Redeamus in circulum.”
22
See Aristotle’s initial characterization of prudence (phronesis, often translated as ‘practical wisdom’):
“Now it is thought to be the mark of a man of practical wisdom to be able to deliberate well about what is
good and expedient for himself . . . about what sorts of things conduce to the good life in
general”(AE.5.5.1140a). Also, “Practical wisdom is the quality of mind concerned with things just and
noble and good for man, but these are the things which it is the mark of a good man to do”
(AE.5.6.1143b21). Leibniz defines ‘prudence’ in a slightly different context, as part of a long series of
definitions in Draft 3: “Prudentia est ars vivendi, seu ars procurandae sibi felicitatis” (A.6.1.457).
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