LAWS OF THOUGHT AND OF THE WORLD. 277 God's wisdom, chosen through his goodness, and realized through his power.* The choice was by no means arbi- trary, but wholly determined by the law of fitness or of the best {principe du meilletir); God's will must realize that which his understanding recognizes as most perfect. It is at once evident that in the competition of the possi- ble worlds the victory of the best was assured by the lex mclioris, apart from the divine decision. This law is the special expression of a more general one, the principle of sufficient reason, which Leibnitz added, as of equal authority, to the Aristotelian laws of thought. Things or events are real (and assertions true) when there is a sufficient reason for their existence, and for their determinate existence. The principiinn ratio7iis sufficientis governs our empirical knowledge of contingent truths or truths of fact, while, on the other hand, the pure rational knowledge of necessary or eternal (mathematical and metaphysical) truths rests on the principiwn contradictionis. The principle of contradiction asserts, that is, Whatever contains a contradiction is false or impossible; whatever contains no contradiction is possible; that whose opposite contains a contradiction is necessary. Or positively formu- lated as the principle of identity, everything and every representative content is identical with itself.f Upon this
- In regard to the dependence of the world on God, there is a certain con-
flict noticeable in Leibnitz between the metaphysical interests involved in the substantiality of individual beings, together with the moral interests involved in guarding against fatalism, and the opposing interests of religion. On the one side, creation is for him only an actualization of finished, unchangeable pos- sibilities, on the other, he teaches with the mediaeval philosophers that this was not accomplished by a single act of realization, that the world has need of conservation, i. e., of continuous creation. f Within the knowledge of reason, as well as in experiential knowledge, a further distinction is made between primaiy truths (which need no proof) and derived truths. The highest truths of reason are the identical principles, which are self-evident ; from these intuitive truths all others are to be derived by demonstration — proof is analysis and, as free from contradictions, demonstra- tion. The primitive truths of experience are the immediate facts of consciousness- ; whatever is inferred from them is less certain than demonstrative knowledge. Nevertheless experience is not to be estimated at a low value ; it is through it alone that we can assure ourselves of the reality of the objects of thought, while necessary truths guarantee only that a predicate must be ascribed to a subject {e. g. , a circle), but make no deliverance as to whether this subject exists or not.
