Page:On the Fourfold Root, and On the Will in Nature.djvu/157

 material truth also, remains an open question and depends on whether the judgment on which it rests has material truth, or whether the series of judgments on which it is founded leads to a judgment which has material truth, or not. This founding of a judgment upon another judgment always originates in a comparison between them which takes place either directly, by mere conversion or contraposition, or by adding a third judgment, and then the truth of the judgment we are founding becomes evident through their mutual relation. This operation is the complete syllogism. It is brought about either by the opposition or by the subsumption of conceptions. As the syllogism, which is the founding of one judgment upon another by means of a third, never has to do with anything but judgments ; and as judgments are only combinations of conceptions, and conceptions again are the exclusive object of our Reason : syllogizing has been rightly called Reason's special function. The whole syllogistic science, in fact, is nothing but the sum-total of the rules for applying the principle of sufficient reason to the mutual relations of judgments ; consequently it is the canon of logical truth.

Judgments, whose truth becomes evident through the four well-known laws of thinking, must likewise be regarded as based upon other judgments ; for these four laws are themselves precisely judgments, from which follows the truth of those other judgments. For instance, the judgment : "A triangle is a space enclosed within three lines," has for its last reason the Principle of Identity, that is to say, the thought expressed by that principle. The judgment, "No body is without extension," has for its last reason the Principle of Contradiction. This again, "Every judgment is either true or untrue," has for its last reason the Principle of the Excluded Middle ; and finally, "No one can admit anything to be true without knowing why," has for its last reason the Principle of Sufficient Reason