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I7» LOCKE. for the communication of knowledge already acquired, and in learned disputations may perform indispensable service in silencing opponents, or in bringing the dispute to a conclusion ; but they are of little or no use in the discovery of new truth. It is a mistake to believe that special cases (as 5 = 2 -f 3, or 5 = i + 4) are dependent on the truth of the abstract rule (the whole is equal to the sum of its parts), that they are confirmed by it and must be derived from it. The particular and concrete is not only as clear and certain as the general maxim, but better known than this, as well as earlier and more easily per- ceived. Nay, further, in cases where ideas are confused and the meanings of words doubtful, the use of axioms is dangerous, since they may easily lend the appearance of proved truth to assertions which are really contradictory. Between the clear daylight of certain knowledge and the dark night of absolute ignorance comes the twilight of probability. We find ourselves dependent on opinion and presumption, or judgment based upon probability, when experience and demonstration leave us in the lurch and we are, nevertheless, challenged to a decision by vital needs which brook no delay. The judge and the historian must convince themselves from the reports of witnesses concern- ing events which they have not themselves observed ; and everyone is compelled by the interests of life, of duty, and of eternal salvation to form conclusions concerning things which lie beyond the limits of his own perception and reflect- ive thought, nay, which transcend all human experience and rigorous demonstration whatever. To delay decision and action until absolute certainty had been attained, would scarcely allow us to lift a single finger. In cases concerning events in the past, the future, or at a distance, we rely on the testimony of others (testing their reports by considering their credibility as witnesses and the conformity of the evi- dence to general experience in like cases) ; in regard to questions concerning that which is absolutely beyond ex- perience, e.g., higher orders of spirits, or the ultimate causes of natural phenomena, analogy is the only help we have. If the witnesses conflict among themselves, or with the usual course of nature, the grounds pro and con must be