Stony Brook University
Stony Brook University
Stony Brook University
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Leibniz’s argument is this: To make the ontological argument valid, the idea of God must<br />
be shown to be possible. This may be shown in two ways: (1) If there is no proof that the<br />
idea of God is impossible, then we may assume that the idea of God is possible. And if<br />
the idea of God is possible, then the rest of the ontological argument holds, and the proof<br />
is valid. Then the “demonstrated moral conclusion” is drawn that we ought to judge that<br />
God exists and act accordingly. (2) It can be proven mathematically that the idea of God<br />
is possible, and therefore that the ontological proof is valid. Presumably this would also<br />
allow us to draw the moral conclusion that we ought to follow God.<br />
As for (1), Leibniz does not tell us whether there are any proofs for the<br />
impossibility of the idea of God. He does however indicate that this premise has a certain<br />
presumptive validity: “for every being should be considered possible until its<br />
impossibility is proven. 64 This claim may seem weak. But we are not talking about just<br />
any being, but about a necessary and perfect being. And since there are no proofs for the<br />
impossibility of the necessary being, we may assume that the idea of God (as a necessary<br />
being) is possible. This argument, then, claims only that we are warranted in making the<br />
assumption that the idea of God is possible. Therefore, the rest of the ontological<br />
argument holds, and God exists. Now, does this result in a demonstrated moral<br />
conclusion? That is to say that from God’s existence alone does it follow that we ought to<br />
obey God? Either Leibniz thinks it is a logical consequence of the proof, or he just thinks<br />
it is best to do so. It is not however a logical consequence of God’s existence that we<br />
ought to follow or obey God.<br />
Leibniz also says that (2) the ontological proof can be completed<br />
“mathematically.” Basically this means that the “assumption” that the idea of God is<br />
possible can be made demonstrably certain. He claims to have done this in the following<br />
way: In his letter to the editor of the Journal de Trévoux (1701), Leibniz claims that the<br />
argument for a most perfect being and a necessary being are essentially the same. 65 In<br />
other words, both arguments show that it cannot be assumed that the idea of God is<br />
impossible, since ‘the idea of God is impossible’ leads to the conclusion that nothing<br />
exists. 66 But it is clear that something exists. And if something exists then it is false that<br />
nothing exists; therefore the necessary being is possible—and the rest of the ontological<br />
proof follows. In other words, if the necessary being is impossible, then all beings which<br />
depend on the necessary being are also impossible—but, something exists, so, the<br />
necessary being is possible. In this way, then, the ontological proof is mathematically<br />
certain and complete, no longer relying on “presumptive validity.”<br />
It should be noted, however, that with this new premise, “something exists,” the<br />
proof depends on an observation or existence claim, and Leibniz has said that existence<br />
metaphysique donne déja une conclusion morale demonstrative, qui porte, que suivant l’état present de nos<br />
connoissances il faut juger que Dieu existe, et agir conformement à cela. Mais il seroit pourtant à souhaiter,<br />
que des habiles gens achevassent la demonstration dans la riguer d’une evidence Mathematique, et je croy<br />
d’avoir dit quelque chose ailleurs, qui y pourra servir.”<br />
64 G.4.405: “Cependant on peut dire que cette demonstration ne laisse pas d’être considerable, et pour ainsi<br />
dire presomptive: car tout estre doit estre tenu possible jusqu’à ce qu’on prouve son impossibilité.”<br />
65 “Extrait d’une lettre de M. de Leibniz sur ce qu’il y a dans les Mémoires de Trévoux” (GP 4.405-6).<br />
66 For this claim Leibniz offers the following argument: “Car si l’Estre de soy est impossible, tous les estres<br />
par autruy le sont aussi, puisqu’ils ne sont enfin que par l’Estre de soy: ainsi rien ne sauroit exister”<br />
(G.4.406).<br />
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