_Uncertain Meaning of a Sentence_, from which confusion arises and fallacious argument may spring. Jevons says: "There is a humorous way of proving that a cat must have three tails: Because a cat has one tail more than _no_ cat; and _no cat_ has two tails; therefore, _any_ cat has three tails." Here the fallacy rests upon a _punning_ interpretation of "no." _Proving the Wrong Conclusion_, in which the attempt to confuse conclusions is made, with the result that some people will imagine that the case is established. Jevons says: "This was the device of the Irishman, who was charged with theft on the evidence of three witnesses, who had seen him do it; he proposed to call _thirty_ witnesses who had _not_ seen him do it. Equally logical was the defense of the man who was called a materialist, and who replied, 'I am not a materialist; I am a barber.'" _Fallacy of Unsuccessful Argument_, in which is attempted the illogical conclusion that _because a certain argument has failed the opposite conclusion is proven_. This fallacy is quite common, especially in cases of juries. One side fails to prove certain contentions, and the jury leaps to the conclusion that the opposite contention must be correct. This is clearly fallacious, for there is always the possibility of a _third_ explanation. In the case of a claim of _alibi_ juries are apt to fall into this fallacy. The failure of the attempt to establish an _alibi_ is often held to be in the nature of proof of the guilt of the accused. Old trial lawyers assert that a failure to establish a claimed _alibi_ tends to injure the chance of the accused more than direct evidence against him. Yet, as all logical reasoners will see, there is no logical validity in any such inference. As Jevons has well said: "_No number of failures in attempting to prove a proposition really disprove it_." At the end of each failure the case simply stands in the same position as before the attempt; _i.e._, "not proven." _All Violations of the Rules of the Syllogism_ constitute fallacies, as may be seen by forming a syllogism in violation of one or more of the rules. The logicians, particularly those of ancient times, took great pains to discover and _name_ new variations of fallacies, many of which were hair-splitting in nature, and not worthy of being considered seriously. Some of those which we have enumerated may possibly be open to the same criticism, but we have omitted many of the worst offenders against practical common sense. An understanding of the fundamental Laws of Reasoning is sufficient to expose and unmask all fallacies, and such understanding is far more valuable than the memorizing of the _names_ of hair-splitting fallacies which would not deceive a child. In addition to the above stated fallacies of Deductive Reasoning, there are other fallacies which are met with in _Inductive Reasoning_. Let us briefly consider them.