just to take interest, it is right to exact it from one’s own father,’ may also be regarded as petitio principii, if we consider the unconditional statement of the premise—­’to take interest upon a loan is perfectly just’; for, surely, this is only conditionally true.  Or, again, the first example given of simple ambiguity—­’that whatever is written in a classical language is classical, etc.,’ may, if we attend merely to the major premise, be treated as a bad generalisation, an undue extension of an inference, founded upon a simple enumeration of the first few Greek and Latin works that one happened to remember.

It must also be acknowledged that genuine wild fallacies, roaming the jungle of controversy, are not so easily detected or evaded as specimens seem to be when exhibited in a Logician’s collection; where one surveys them without fear, like a child at a menagerie.  To assume the succinct mode of statement that is most convenient for refutation, is not the natural habit of these things.  But to give reality to his account of fallacies an author needs a large space, that he may quote no inconsiderable part of literature ancient and modern.

As to the means of avoiding fallacies, a general increase of sincerity and candour amongst mankind may be freely recommended.  With more honesty there would be fewer bad arguments; but there is such a thing as well-meaning incapacity that gets unaffectedly fogged in converting A., and regards the refractoriness of O., as more than flesh and blood can endure.  Mere indulgence in figurative language, again, is a besetting snare.  “One of the fathers, in great severity called poesy vinum daemonum,” says Bacon:  himself too fanciful for a philosopher.  Surely, to use a simile for the discovery of truth is like studying beauty in the bowl of a spoon.

The study of the natural sciences trains and confirms the mind in a habit of good reasoning, which is the surest preservative against paralogism, as long as the terms in use are, like those of science, well defined; and where they are ill defined, so that it is necessary to guard against ambiguity, a thorough training in politics or metaphysics may be useful.  Logic seems to me to serve, in some measure, both these purposes.  The conduct of business, or experience, a sufficient time being granted, is indeed the best teacher, but also the most austere and expensive.  In the seventeenth century some of the greatest philosophers wrote de intellectus emendatione; and if their successors have given over this very practical inquiry, the cause of its abandonment is not success and satiety but despair.  Perhaps the right mind is not to be made by instruction, but can only be bred:  a slow, haphazard process; and meanwhile the rogue of a sophist may count on a steady supply of dupes to amuse the tedium of many an age.

FINIS.

QUESTIONS