9. SUMMARY.
(1) Logic as a science makes known the laws and forms of thought and as an art suggests conditions which must be fulfilled in order to think rightly.
A discussion of the second phase of the definition would be incomplete without a consideration of the negative aspect as well as the positive. Such a viewpoint makes evident the question “What errors must be avoided in order to reason correctly?” An answer to this question is given under the caption of Logical Fallacies.
(2) A logical fallacy is any error in reasoning which has the appearance of correctness.
A fallacy which deceives the writer or speaker himself is termed a paralogism, whereas a fallacy formed for the express purpose of deceiving another is denominated a sophism.
It was the pagan teacher Socrates who taught modern thought to frown upon all forms of sophism; these exist to-day much as they did in the olden time.
(3) Because of disagreement as to definition, and because of inability to prevent an overlapping of species, any logical division of the deductive fallacies must be faulty.
In the division of the deductive fallacies, this treatise retains the phraseology and form worked out by Aristotle, so far as such retention is consistent with the changes incident to the advances of time.
(4) Formal fallacies occur because of careless and improper use of words as arbitrary signs. Formal fallacies are definite and easy of comprehension.
The material fallacies are due to certain inconsistencies in thought and to imperfect ways of interpreting language. They are more subtle and thus more difficult of comprehension than the formal fallacies.
There are material fallacies in thought and material fallacies in language; the former are due to looseness in thinking and the latter to lack of precision in expression.
(5) Fallacies of opposition result most frequently from deriving universals from their corresponding particulars, and from assuming to contradict affirmative universals by negative universals and affirmative particulars by negative particulars.
The common fallacy in the process of obversion consists in using one negative instead of two, whereas the ordinary error of conversion is a matter of distributing an undistributed term.
Fallacies of contraversion must involve either those of obversion or conversion since the process is a combination of the two.
(6) Fallacies in language, because they result from permitting more than one interpretation, may be also denominated fallacies of equivocation.
(1) Ambiguous middle is the fallacy of giving to the middle term a double meaning.
The fallacy of four terms, as the name signifies, exists when the argument has four terms in both form and meaning. Ambiguous middle is a matter of four terms in meaning but only three in form.
(2) The fallacy of amphibology is committed when the given proposition conveys more than one meaning. In order to maintain their prestige the ancient oracles made use of this fallacy.
(3) The fallacy of accent springs from placing undue emphasis on some word or group of words. Newspaper and demagogues are prone to this error, that they may thus create an unfavorable impression towards those whom they oppose.
(4) The fallacy of composition is committed when it is assumed that what is true distributively is likewise true collectively. “All” meaning each one and “all” meaning the whole class often leads to the fallacy of composition.
(5) The fallacy of division is committed when it is assumed that what is true collectively is true distributively.
Division is the converse of composition.
(6) The fallacy of figure of speech is occasioned by assuming that words of the same root have the same meaning.
(7) Fallacies in thought are likewise called fallacies of assumption, because of the tendency to assume as true something which demands further proof.
(1) The fallacy of accident occurs when one reasons from a general truth to an accident case. It is the favored fallacy of the doctrinaire, the reformer and the vender of “cure-alls.”
(2) The fallacy of converse accident occurs when one reasons from an accidental case to a general truth.
Both accident and converse accident are made possible because rules, definitions, maxims, etc., have exceptions. It is easy to confuse division and composition with the fallacies of accident. Division and composition are concerned with the collective and distributive use of terms, whereas the fallacies of accident involve the use of notions in a general and accidental sense. The former represent notions which may be counted or enumerated while the latter concern notions which are logical rather than numerical. Composition and division involve “number of,” accident, “meaning of.”
(3) The fallacy of irrelevant conclusion results when the argument does not squarely meet the point at issue. It is the fallacy of arguing to the wrong point either purposely or ignorantly. This may be accomplished by (1) appealing to sympathy of audience, (2) defaming character of opponent, (3) assuming that the fact is true because of inability to prove the contradictory, (4) gaining point by force, (5) citing authority.
(4) “Non sequitur” is the fallacy of deriving a conclusion which does not follow from the premises. It involves introducing new material in the conclusion.
(5) “False cause” is the fallacy of assuming that because two happenings have occurred together several times the one is the cause of the other. The fallacy is due largely to the exaggerations of fear and superstition.
(6) The fallacy of complex question consists in putting an assumption in the form of a question.
(7) Begging the question is the fallacy of deriving a conclusion from notions which in themselves demand proof.
This fallacy takes the three forms of (1) the assumption of an unproved premise, (2) reasoning in a circle, (3) question begging epithets and appellations.
10. ILLUSTRATIVE EXERCISES IN THE TESTING OF ARGUMENTS IN BOTH FORM AND MEANING.
(1a) He who wilfully takes the life of another should be electrocuted,
This sharp shooter has wilfully taken the life of another,
Hence he should be electrocuted.
In form we know this argument to be valid since it is in mood
A
A
A
of the first figure. But as the conclusion does not meet with our approval, we are forced to the belief that there must be a material fallacy. Such proves to be the case. In the first instance, “Wilfully takes the life of another” is used in a personal, individual, selfish sense, whereas in the second instance the expression is used in a general, “servant-of-the-government” signification. The argument is, therefore, invalid, the fallacy being ambiguous middle.
(1b) From the viewpoint of both form and meaning test the following: “Events which are not probable happen almost every day; but what happens every day are very probable events; therefore events which are not probable are very probable.”
(2a) The planets have those attributes needed in the support of life,
Mars is a planet,
Hence Mars has those attributes needed in the support of life.
This is valid in form
A
A
A
in the first figure. The major premise posits a fact which has not been proved; the argument is therefore invalid in meaning, the fallacy being that of begging the question.
(2b) “The end of a thing is its perfection; death is the end of life, therefore death is the perfection of life.”
Indicate the fallacy in the foregoing, giving reasons.
(3a) The countries of Europe abound in beggars,
France is a country in Europe,
∴ France abounds in beggars.
“The countries of Europe” in the major premise is used in a collective sense, while the same expression in the minor premise is used in a distributive sense. The argument is, therefore, invalid in meaning; fallacy of division.
(3b) State and explain the material fallacy in the following:
The states believe in the income tax principle; hence Vermont’s vote will be favorable to this.
(4a) “On general principles I believe that one is better off when he abstains from both tea and coffee; and this is the reason why I offer you a cup of hot water.”
The individual to whom the hot water was offered might have been in great need of a mild stimulant. Here, then, is an exception to the general principle and the fallacy committed is clearly that of accident.
(4b) “Books are a source both of instruction and amusement; a table of logarithms is a book; therefore it is a source both of instruction and amusement.” Jevons.
Designate with explanations the fallacy in the above argument.
(5) “Twice have I started out on Friday and both times I had tire trouble.” Fallacy of false cause.
(6) “Where do you spend your vacation, in Palestine or Rome?” Fallacy of complex question.
(7) “Of all the men of that department he seemed to be the most trustworthy, and I pride myself on my ability to judge men in this regard; but now even the police cannot find him.”
The fact that the police cannot find him has nothing to do with the argument. The fallacy is that of non sequitur.
(8) “You must not whisper in my classes.” Fallacy of accent.
(9) “I am a Progressive because I believe in progress.” Fallacy of figure of speech.
(10) “I know it is true because I found it in our text book.” Fallacy of irrelevant conclusion.
11. REVIEW QUESTIONS.
(1) Give the negative aspect of the second part of the definition of logic.
(2) Define and illustrate the term fallacy as it is used in logic.
(3) Distinguish between a paralogism and a sophism.
(4) Tell of the mission of Socrates.
(5) What reasons may be given for such a divergence of opinion on a proper classification of the fallacies of deduction?
(6) Give a complete outline, without explanation, of the deductive fallacies.
(7) Distinguish between formal and material fallacies.
(8) Explain the two kinds of material fallacies.
(9) Illustrate the fallacies of immediate inference.
(10) Why should the fallacies in language be likewise termed fallacies of equivocation?
(11) Explain and illustrate ambiguous middle.
(12) Illustrate the fallacy of amphibology.
(13) Explain by illustration the fallacy of accent.
(14) Explain and exemplify the fallacies of composition and division.
(15) Illustrate the fallacy of figure of speech.
(16) Give reasons for denominating the fallacies in thought as fallacies also of assumption.
(17) Define and illustrate the fallacies of accident and converse accident.
(18) Distinguish between the fallacies of composition and division and the two fallacies of accident.
(19) “Every rule has its exception,” what has this to do with the fallacies of accident?
(20) Explain and illustrate the fallacy of irrelevant conclusion.
(21) Name the various ways in which irrelevant conclusion may be committed.
(22) Illustrate the fallacy of non sequitur.
(23) Explain the fallacy of false cause.
(24) Give examples of the complex question.
(25) How may the teacher use the complex question to advantage?
(26) Explain the fallacy of begging the question.
(27) Illustrate the three forms of begging the question.
(28) From the viewpoint of form and meaning, test the validity of the following:
(1) “No soldiers should be brought into the field who are not well qualified to perform their part; none but veterans are well qualified to perform their part, therefore, none but veterans should be brought into the field.” Whately.
(2) “For the proverb is true, ‘That light gains make heavy purses;’ for light gains come thick, whereas great gains come but now and then.” Bacon.
(3) “Whatever is given on the evidence of sense may be taken as a fact; the existence of God, therefore, is not a fact, for it is not evident to sense.” St. Andrew. 1896.
(4) “All the trees in the park make a thick shade; this is one of them, therefore this tree makes a thick shade.” Jevons.
(5) “What we eat grew in the field; loaves of bread are what we eat; therefore loaves of bread grew in the fields.” Jevons.
(6) “Who is most hungry eats most; who eats least is most hungry; therefore who eats least eats most.” Jevons.
(7) “Great talkers should be cropped, for they have no need of ears.” Franklin.
(8) “Love your enemies, for they tell you your faults.” Franklin.
(9) “All the works of Shakespeare cannot be read in a day; therefore the play of Hamlet, being one of the works of Shakespeare, cannot be read in a day.” Jevons.
(10) “Logic as it was cultivated by the schoolmen proved a fruitless study; therefore logic as it is cultivated at the present day must be a fruitless study likewise.” Jevons.
12. QUESTIONS FOR ORIGINAL THOUGHT AND INVESTIGATION.
(1) Is there any difference in content between error and fallacy? Illustrate.
(2) In what ways do trusts indulge in sophisms?
(3) May the sophism be used conscientiously by the country doctor? Explain.
(4) Give in substance Aristotle’s classification of fallacies.
(5) Select the fallacies which could with justice be called fallacies of interpretation. See Creighton.
(6) Explain in full the popular conception of equivocation.
(7) Indicate the marks which distinguish the following: Ambiguous middle, fallacy of four terms, non sequitur, figure of speech.
(8) “Why should Jeremy Bentham employ a person to read to him who habitually read in a monotonous tone of voice?” Jevons—Hill.
(9) Originate a sentence of about ten words and through the fallacy of accent secure as many different meanings as possible.
(10) Show that the fallacy of figure of speech might be classed as a fallacy of four terms.
(11) To what fallacies, in your opinion, are teachers especially given?
(12) Show that the fallacy of accident could be classed as one of ambiguous middle.
(13) “When the Puritan settlers in New England passed their three famous resolutions—Resolved, first, that the earth is the Lord’s and the fullness thereof; secondly, that he hath given it to his Saints; thirdly, that we are his Saints. What fallacy did the Puritan Fathers commit?” Ryland.
(14) A Dutchman afflicted with pneumonia arises at midnight and eats a large quantity of sauerkraut. The Dutchman gets well, whereat his physician writes in his little book on remedies, “Sauerkraut sure cure for pneumonia.” The physician was guilty of what fallacy? Why?
(15) De Morgan quotes from Boccaccio this: “A servant who was roasting a stork for his master was prevailed upon by his sweetheart to cut off a leg for her to eat. When the bird came upon the table the master desired to know what had become of the other leg. The man answered that storks never had more than one leg. The master, very angry, but determined to strike his servant dumb before he punished him, took him next day into the fields where they saw storks, standing each on one leg, as storks do. The servant turned triumphantly to his master; on which the latter shouted, and the birds put down their other legs and flew away. Ah, sir, said the servant, you did not shout to the stork at dinner yesterday; if you had done so he would have shown his other leg.” What fallacy does this quotation from Boccaccio illustrate?
(16) Why should begging the question and irrelevant conclusion be classed as fallacies of the “forgotten issue?”
(17) From the standpoint of both form and meaning test the validity of the following:
(1) “Virtue is the child of knowledge and vice of ignorance; therefore education, periodical literature, traveling, ventilation, drainage and the arts of life, when fully carried out, serve to make a population moral and happy.” Hibben.
(2) “The civil power has the right of ecclesiastical jurisdiction and administration, therefore parliament may impose articles of faith on the church or suppress dioceses.” Hibben.
(3) “Seeing that abundance of work is a sure sign of industrial prosperity, it follows that fire and hurricane benefit industry, because they undoubtedly create work.” St. Andrews—1895.
(4) “Riches are for spending, and spending for honor and good action; therefore, extraordinary expense must be limited by the worth of the occasion.” Bacon.
(5) “And let a man beware how he keepeth company with choleric and quarrelsome persons; for they will engage him into their own quarrels.” Bacon.
(6) “He that resteth upon gains certain, shall hardly grow to great riches; and he that puts all upon adventures, doth oftentimes break and come to poverty. It is good, therefore, to guard adventures with certainties that they may uphold losses.” Bacon.