History of Western Philosophy - Bertrand Russell [332]
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 are formalized by the scholastics, and one of them, the ontological argument, was invented by St Anselm. This argument, though rejected by St 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 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.
The ontological argument depends upon the distinction between existence and essence. Any ordinary person or thing, it is held, on the one hand exists, and on the other hand has certain qualities, which make up his or its 'essence'. Hamlet, though he does not exist, has a certain essence; he is melancholy, undecided, witty, etc. When we describe a person, the question whether he is real or imaginary remains open, however minute our description may be. This is expressed in scholastic language by saying that, in the case of any finite substance, its essence does not imply its existence. But in the case of God, defined as the most perfect Being, St Anselm, followed by Descartes, maintains that essence does imply existence, on the ground that a Being who possesses all other perfections is better if He exists than if He does not, from which it follows that if He does not He is not the best possible Being.
Leibniz neither wholly accepts nor wholly rejects this argument; it needs to be supplemented, so he says, by a proof that God, so defined, is possible. He wrote out a proof that the idea of God is possible, which he showed to Spinoza when he saw him at the Hague. This proof defines God as the most perfect Being, i.e. as the subject of all perfections, and a perfection is defined as a 'simple quality which is positive and absolute, and expresses without any limits whatever it does express'.