A new logic / by Charles Mercier.

  • Mercier, Charles Arthur, 1852-1919.
Date:
1912
Catalogue details

Licence: In copyright

Credit: A new logic / by Charles Mercier. Source: Wellcome Collection.

    443/458 (page 411)
    INFERENCE The others are of doubtful validity, and of still more doubtful utility. Of the eight classes that actually exist of Immediate Inferences; of the indefinitely numerous multitude of Inferences that are included in these eight classes, all valid, and all in frequent use, Traditional Logic knows no more than I know of the configuration of the surface of the other side of the moon, or of the mental process by which logicians persuade themselves that the Laws of Thought and the Dictum de omni are of any importance. Traditional Logic can no more infer from ‘ She saw him do it ’ to ‘ She was there when he did it ’ than it can infer from ‘ He designed a sundial ’ to ‘ He was conversant with Astronomy and Geometry.’ All that Traditional Logic can obtain from these postulates is ‘ Some person who saw him do it was she,’ ‘ Some person who did not design a sundial was not he,’ and ‘ It was not he that did not design a sundial.’ Whether these inferences compare in elegance and value with the first two, the reader must judge. As for Mediate Inference, the crowning achievement of Traditional Logic, to which this Logic owes its enormous prestige, it is applicable to a small proportion only of Compound propositions; from the small proportion to which it is applicable it can extract but one, or at most two, of the multitudes they may contain; it is not self-evidently valid, but needs, in most cases, an awkward, cumbrous, and complicated process of reduction to make it appear so ; its rules are faulty ; and it cannot be applied without a knowledge of the barbarous mnemonic verses. And this clumsy and inefficient process, of extremely limited applica- tion, and still more limited utility, is the crown and flower of Traditional Logic; its pride and its glory; its one title to the reverence and applause that mankind have, for two thousand years, so freely and lavishly bestowed upon it. Never, in the long history of man, has kudos been obtained so cheaply. Of Analogy, in the strict Aristotelian sense, which is a valid, telling, useful, and frequently employed mode of reasoning, nothing is known by any system of Logic hitherto devised, though Spencer, who was not a logician, recognised its use and value. If logicians mention it at all, they either confuse it with Empirical Reasoning, or they fail to appreciate that it is a mode of reasoning at all. The reasonings of Mathematics have no part or lot in any