_Irrelevant Conclusion_--the fallacy called by Aristotelians _Ignoratio elenchi_--is an attempt to substitute a better argument for the one proposed, but which proves something which has not been denied, or stigmatises something that has not been asserted. It frequently arises from honest ignorance of the question at issue, as in the objections usually made to the Berkeleyan Substantialism. It can also be used as a weapon of sophistry, by confusing the matter in dispute or diverting attention to side issues. It is irrelevant to the truth of a conclusion to point out that he who now supports it formerly opposed it, or that his conduct is inconsistent with a belief in it. Appeals to passion--to reverence for authority--to popular belief--are instances of this fallacy. The best protection against Fallacy--next to a thorough knowledge of the matter--is a clear notion of the properties of a valid argument; it is useful however to be able to distinguish and name the faulty theorems one constantly meets in controversial speeches and writings. [Footnote 17: One fault of observation is noticed by formal logicians; it is that of assigning an improper cause, _Non causa pro causâ_ or _Post hoc ergo propter hoc_. It is evident that defects in every other category have an equal light to be noticed.] [Footnote 18: Whately complains of the disinclination shown by logicians to put their rules into practice. 'Whenever they have to treat of anything that is beyond the mere elements of Logic, they totally lay aside all reference to the principles they have been occupied in establishing and explaining, and have recourse to a loose, vague, and popular kind of language; such as would be best suited indeed to an exoterical discourse but seems strangely incongruous in a professed logical treatise.... Surely it affords but too much plausibility to the cavils of those who scoff at Logic altogether, that the very writers who profess to teach it should never themselves make any application of, or reference to, its principles, when, and _when only_, such application and reference are to be expected.' _Logic_, Book III. Introd. The fact here admitted proves that even logicians do not find their method of any practical use. But what is the meaning of the emphatic 'when only'? Why should a logical method be unsuitable for every sort of subject except those matters of logic that are beyond the mere elements?] [Footnote 19: _Logic_, 'Fallacies,' c. 6.] ACADEMICAL DIALECTIC XXXI--ANALOGY Logicians of Greek inspiration apply the term reasoning or argument to at least eight different intellectual operations, some of them important indeed but only one of them argument. This is Analogy--which receives but little notice from logicians because it does not give certain conclusions. The operations mistaken for argument are: