but the sufficient reason of his action has no logical necessity. So, at least, Leibniz says when he is
writing popularly, but, as we shall see, he had another doctrine which he kept to himself after
finding that Arnauld thought it shocking.
God's actions have the same kind of freedom. He always acts for the best, but He is not under any
logical compulsion to do so. Leibniz agrees with Thomas Aquinas that God cannot act contrary to
the laws of logic, but He can decree whatever is logically possible, and this leaves Him a great
latitude of choice.
Leibniz brought into their final form the metaphysical proofs of God's existence. These had a long
history; they begin with Aristotle, or even with Plato; they were formalized by the scholastics, and
one of them, the ontological argument, was invented by Saint Anselm. This argument, though
rejected by Saint Thomas, was revived by Descartes. Leibniz, whose logical skill was supreme,
stated the arguments better than they had ever been stated before. That is my reason for examining
them in connection with him.
Before examining the arguments in detail, it is as well to realize that modern theologians no
longer rely upon them. Medieval theology is derivative from the Greek intellect. The God of the
Old Testament is a God of power, the God of the New Testament is also a God of love; but the
God of the theologians, from Aristotle to Calvin, is one whose appeal is intellectual: His existence
solves certain puzzles which otherwise would create argumentative difficulties in the
understanding of the universe. This Deity who appears at the end of a piece of reasoning, like the
proof of a proposition in geometry, did not satisfy Rousseau, who reverted to a conception of God
more akin to that of the Gospels. In the main, modern theologians, especially such as are
Protestant, have followed Rousseau in this respect. The philosophers have been more
conservative; in Hegel, Lotze, and Bradley arguments of the metaphysical sort persist, in spite of
the fact that Kant professed to have demolished such arguments once for all.
Leibniz's arguments for the existence of God are four in number; they are (1) the ontological
argument, (2) the cosmological argument, (3) the argument from the eternal truths, (4) the
argument from the pre-established harmony, which may be generalized into the argument from
design, or the physico-theological argument, as Kant calls it. We will consider these arguments
successively.