Stony Brook University

person. 20
Thus if God is going to uphold the name of the good person, then a certain moral
necessity is indeed imposed on God.
Section 3: Late formulations in the correspondence with Clarke
It would be chronologically appropriate to turn to Leibniz’s use of “moral
necessity” in the “action-theoretic” context (as Murray puts it) of Theodicy. However, to
get a much clearer idea of the distinction between moral and metaphysical necessity that
Leibniz makes there, it is best to leap ahead to Leibniz’s correspondence with Clarke
(1716). The following passage, in which Leibniz attributes to Clarke the same confusion
he attributed to Bayle, is especially succinct and illustrative. 21
He [Clarke] seems to play with equivocal terms. There are necessities, which
ought to be admitted. For we must distinguish between an absolute and an
hypothetical necessity. We must also distinguish between a necessity, which takes
place because the opposite implies a contradiction; (which necessity is called
logical, metaphysical, or mathematical;) and a necessity which is moral, whereby,
a wise being chooses the best, and every mind follows the strongest inclination.
(5 th letter, §4 p. 56) 22
It may appear as if Leibniz distinguishes as many as seven kinds of necessity here;
however, there are basically only two types anywhere: absolute and hypothetical, under
which are several species. Under absolute necessity falls logical, metaphysical, and
mathematical necessity. This necessity refers to propositions whose truth value depends
solely on the principles of non-contradiction and identity. Propositions the denial of
which results in a contradiction are necessarily true. Necessary truths are either explicit
identities or are reducible to them. Propositions the denial of which does not entail a
contradiction are contingent or hypothetically necessary propositions. A true hypothetical
proposition expresses actual existence, while one that fails to express actual existence is
false. Actual existence depends on God, who “decides” to make what is hypothetical a
reality. Thus, a truth is morally necessary (hypothetically necessary) just in case God has
decided to make it a reality. God’s decision is said to be based on the criterion of
perfection. 23 It is also important to note that the end of this passage offers a general
explanation for action and moral failure. A mind, any mind, (and correspondingly any
body) always follows the strongest inclination. That is, it follows whatever it has
20 A.6.4.2850: “Itaque jus quod habemus agendi vel non agendi, est potentia quaedam sive libertas moralis.
Obligatio autem est moralis necessitas, illi nimirum imposita, qui viri boni nomen tueri velit.”
21 I use the H.G. Alexander translation.
22 G.7.389: “Il semble aussi, qu’on se joue d’equivoques. Il y a des necessités, qu’il faut admettre. Car il
faut distinguer entre une necessité absolue et une necessité hypothetique. Il faut distinguer aussi entre une
necessité qui a lieu, parce que l’opposé implique contradiction, et laquelle est appellée logique,
metaphysique ou mathematique; et entre une necessité qui est morale, qui fait que le sage choisit le
meilleur, et que tout esprit suit l’inclination la plus grande.”
23 See Rescher (2002) for a very thorough and interesting account of this criterion.
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