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sources of knowledge. Through experience they are made explicit, and indeed make
experience possible. 58 Presumably, if we reflect adequately, namely, through
demonstration, we can gain clear and distinct knowledge of these eternal truths.
These claims are important to keep in mind in relation to Leibniz’s arguments in
the Meditation on the Common Concept of Justice. As we will see, Leibniz claims that
God’s mind is the domain of eternal truths, the domain of formal objects of definitions,
i.e., essences, and that justice has such an essence. If the real definition of justice is to be
distinguished from merely nominal, contingent, changeable definitions, and is to be
distinguished from truths of fact, then it must be an eternal truth. In this sense the
“concept of justice” is common to both God and humans. It must also be so grounded, if
the true idea of justice is to be known to our mind.
With this in mind, it helps to see one more passage in which Leibniz attempts to
refute the nominalist, here in response to Locke’s claim that “truths will be either mental
or nominal, according to the kind of sign.” Leibniz writes:
It would be better to assign truth to the relationships amongst the objects
of the ideas, by virtue of which one idea is or is not included within
another. That does not depend on languages, and is something we have in
common with God and the angels. And when God displays a truth to us,
we come to possess the truth which is in his understanding, for although
his ideas are infinitely more perfect and extensive than ours they still have
the same relationships that ours do. So it is to these relationships that truth
should be assigned; and we can distinguish truths, which are independent
of our good pleasure, from expressions, which we invent as we see fit.
(NE 397) 59
It is the relationship among ideas that ultimately matters, not the relations of inadequately
analyzed words. While God’s idea of, say, justice, is more perfect and extensive than
ours, it remains true that our idea of justice is consistent with it, and consistent with the
ideas to which it relates. Leibniz is also speaking of the difference between the real
definition of an idea and a nominal expression of it. But he maintains that we do not have
the real definition unless we have analyzed it as far as possible. This is how we can know
the real definitions of things that reside in God’s mind, and thus avoid the nominalist
mistake.
It must be said, however, that a significant problem with this dependence on
definitions remains. On one hand, if the concept to be defined has clearly identifiable
properties, such as a triangle, it is hard to imagine that its definition could be refuted or
considered merely conventional. But for an abstract idea such as justice, it is hard to see
how a conventional definition can really be avoided. Such ideas can be shown to be
58 I discuss innate ideas in more detail in Chapter Five.
59 A.6.6.397: “Il vaut donc mieux placer les verités dans le rapport entre les objets des idées, qui fait que
l’une est comprise ou non comprise dans l’autre. Cela ne depend point des langues, et nous est commun
avec Dieu et les Anges. Et lors que Dieu nous manifeste une verité nous acquerons celle qui est dans son
entendement, car quoique il y ait une difference infinie entre ses idées et les nostres, quant à la perfection et
à l’entendue, il est tousjours vray qu’on convient dans le même rapport. C’est donc dans ce rapport qu’on
doit placer la verité, et nous pouvons distinguer entre les verités qui sont independantes de notre bon plaisir,
et entre les expressions, que nous inventons comme bon nous semble.”
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