“Fallacy” comes from the Latin _fallacia_, meaning deceptive or erroneous, and therefore _a fallacy in logic is any error in reasoning which has an appearance of correctness_. If the writer or speaker is _himself_ deceived by the fallacy, then such is called a _Paralogism_; but if the fallacy is committed by him for the expressed purpose of deceiving others, then such becomes a _Sophism_. During the time of the Schoolmen the Sophism was in such high repute that it required even a Socrates to puncture this ignominious bubble of vain trickery. In fact, Socrates, the greatest of all pagan educators, _led_ the crusade which has relegated to the “logical dust bin” the notion that _skill in the art of framing sophisms is a scholarly accomplishment_. Many believe modern sophistry to be the chief social and commercial evil of the day, and to Socrates must be given the credit for teaching us to look upon those who would practice sophism with righteous indignation and pronounced disgust. However, paralogism and not sophism is the more legitimate field for the student of logic; his problem being, “What are the common errors which I, as a writer and speaker, must strive to avoid?” =3. A DIVISION OF THE DEDUCTIVE FALLACIES.= The mistakes of induction will occupy our attention in a later chapter. We are now concerned with the fallacies of deduction. Any classification or division of the deductive fallacies must of necessity be faulty. Even the labors of Aristotle in this regard are now pronounced crude and unsatisfactory. This is due to the divergence of opinion as to the signification of some of the fallacies, as well as to the fact that no division is free from the fault of an _overlapping_ of the species. As a result of this lack of unanimity in definition and lack of ability in making the species mutually exclusive, any division of the deductive fallacies must be more or less illogical. Aristotle divides the fallacies of deduction into two groups: (1) Fallacies _in dictione_, or formal fallacies. (2) Fallacies _extra dictionem_, or material fallacies. This division has received universal approval and though many distinctions made by him have been abandoned, yet most logicians retain his phraseology. Since many of the technical terms which Aristotle used have lived through the generations under the conventional meaning which he assigned to them, it becomes less confusing to adhere as closely as possible to these terms. Therefore, in the attending division only those changes have been made which progress and experience have forced upon us. What remains of this chapter will be devoted to explaining these fallacies as they appear in this division. For the sake of clearness and definiteness it is strongly recommended that the student study the outline extensively enough to be able to reproduce it. _Fallacies._ _Formal_ (_In dictione_)