Stony Brook University

experience and even from confused perceptions within us. So you see, sir,
that I do not accept what you lay down as a fact, namely that we can
acquire all our knowledge without the need of innate impressions. (NE
1.1.1.75) 20
This way of beginning should be familiar to us by now. As in the Nova Methodus and
Elementa, Leibniz begins with the distinction between two kinds of truth—a priori,
necessary truths of reason, and a posteriori, contingent truths of fact.
However, a distinguishing feature of the Nouveaux Essais is its arguments for the
innateness of practical principles. Particularly unusual is the claim, not that there are
innate practical truths of reason (even though there are), but rather that there are innate
practical truths of fact. As we will see Leibniz agrees with Locke, to a point, that the
principles of pleasure and pain are innate, practical, and demonstrable moral principles.
In fact, Leibniz will argue that there many such practical sensual instincts. At the same
time, while instincts provide us with indications of moral rightness, they do not
ultimately provide sufficient grounds for moral justification and certainty. Instincts are
largely descriptive principles of motivation, not normative justifications. The moral
justification for an action is determined in several ways: by the “assumptions” of the
existence of God and immortality; by the “command of reason” stemming from the
natural law of the Gospel; by a rule like the Golden Rule, or by what he calls later the
fundamental maxims of pure reason. We will examine each of these determinations and
the sense in which knowledge of them is said to be innate.
Leibniz’s arguments for innate speculative principles are important and in many
ways parallel to his arguments on innate practical principles. However, it is sufficient for
our purposes to focus only on the latter. To begin the chapter on innate practical
principles, Locke is taken to claim that although moral doctrine (la Morale) is a
demonstrative science, it has no innate principles. Indeed, it will be difficult if not
impossible to find a moral rule capable of universal assent—and certainly not as capable
of assent as are speculative principles, such as the “maxim” of identity. For Leibniz,
however, the lack of universal assent does not disprove the universal validity of a
principle, nor whether it is innate. But he responds to Locke here by claiming that in
respect of self-evidence (i.e., indemonstrability) practical principles are just as selfevident
as speculative practical principles. The former, however, are self-evident by
experience, not by reason.
It is absolutely impossible that there should be truths of reason which are
as evident as identities or immediate truths. [And] although it is correct to
say that morality has indemonstrable principles, of which one of the first
and most practical is that we should pursue joy and avoid sorrow, it must
be added that that is not a truth which is known solely from reason, since it
is based on inner experience – on confused knowledge; for one only
20 A.6.6.75: “Mais il semble que l’auteur a eté porté trop loin d’un autre coté par son zele fort louable
d’ailleurs. Il n’a pas assés distingué à mon avis l’origine des verités necessaires, dont la source est dans
l’entendement, d’avec celle des verités de fait, qu’on tire des experiences des sens, et meme des perceptions
confuses qui sont en nous. Vous voyés donc, Monseiur, que je n’accorde pas ce que vous mettés en fait,
que nous pouvons acquerir toutes nos connoissances sans avoir besoin d’impressions innées.”
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