Stony Brook University

insufficient to motivate us to do our duty. The best we can say for demonstration, then, is
that it has the function of providing a more “distinct” moral knowledge than the
“confused” inclinations of instinct.
In this section I want show how Leibniz could have integrated two principles of
sense and reason in an account of virtue. We have seen Leibniz argue that sense instincts
have a certain moral content. That is, they are indicators of what reason commands. For
example, the social instinct or the instinct to love another points us in a general moral
direction, and reason tells us we ought to do this as well. At the same time, a sense
instinct can be unreliable, if it leads us, for example, straight to a present joy and away
from lasting happiness. Leibniz has indicated that reason is required to regulate our
instincts and passions. But he has also suggested that moral action often depends the aid
of instinct.
First, I want to suggest that in some fundamental ways Leibniz’s convictions
about the aim and content of morality are not so different from Kant’s, as expressed in
this passage from the Metaphysics of Morals:
For since the sensible inclinations of human beings tempt them to ends
(the matter of choice) that can be contrary to duty, lawgiving reason can in
turn check their influence only by a moral end set up against the ends of
inclination, an end that must therefore be given a priori, independently of
inclinations. (Metaphysics of Morals 146) 85
For Kant, since inclinations tend to oppose what duty tells us is right, they can be
opposed only by a moral end given prior to all inclinations, and this moral end is the
moral law itself. Although Leibniz did not argue for a moral law in Kant’s sense, his
arguments do tend toward the position that there is a moral end independent of
inclinations of instinct and sense. In addition, the grounding principles of morals, the
criteria for right, just, and justice, have the nature of pure reason. Furthermore, these
principles must regulate our inclinations, passions, and instincts. It should of course be
recognized that unlike Kant, Leibniz does not insist on such a strict separation between
sense and reason. If fact, on some level Leibniz cannot separate them entirely, since the
possibility of moral action depends on an initial sensual motive in the agent. 86 For
Leibniz, the ends of moral action need not be given strictly independently of sense
instincts, since the latter provide some indication of what our moral ends are. Instincts
direct us first to the good when reason often does not or cannot. But they do not tell us
what our moral ends are.
We now need to understand more closely how Leibniz configures the relationship
between principles of sense and reason. First, it is important to see that Leibniz
85 Metaphysik der Sitten: 254/380-381: “Denn da die sinnlichen Neigungen zu Zwecken (also der Materie
der Willkür) verleiten, die der Pflicht zuwider sein können, so kann die gesetzgebende Vernunft ihrem
Einfluß nicht anders wehren als wiederum durch einen entgegengesetzten moralischen Zweck, der also von
der Neigung unabhängig a priori gegeben sein muß.”
86 On the other hand, it is not so easy for Kant to maintain the separation. Kant has considerable difficulty
explaining how the moral law can be an incentive to act against sensual inclinations, without this incentive
also being a sensual inclination. Is moral feeling a purely rational respect for the moral law? If so, how does
it oppose the senses? Or is moral feeling a “pleasure of the mind,” as Leibniz and the Stoics would say
about honor?
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