EXERCISES IN DEDUCTIVE ARGUMENT
EXERCISES IN DEDUCTIVE ARGUMENT
EXERCISES IN DEDUCTIVE ARGUMENT
I. Construct valid syllogisms showing the reasoning involved in each of the following enthymemes:
1. Since large corporations are gaining control of all industries a Federal incorporation law should be enacted.
2. As swollen fortunes are an evil, a progressive inheritance tax should be enacted.
3. Commercial reciprocity between the United States and Canada would be for the best interest of the United States because it would reduce the high cost of living.
4. Because compulsory insurance has been successful in Germany, it should be adopted in the United States.
5. On account of the growth of the divorce evil in the United States, there should be a Federal law regulating marriage and divorce.
6. There should be a state censorship of the stage because many immoral productions are being brought before the public.
7. “Blessed are the meek for they shall inherit the earth.”
II. Diagram, by means of circles, the syllogisms constructed under exercise I.
III. State three instances in which you have recently employed deductive argument.
IV. Write a deductive argument of not less than three hundred words.
CHAPTER IIIARGUMENT FROM CAUSAL RELATION
Arguments from causal relation are divided into three classes, I. Arguments from Effect to Cause, II. Arguments from Cause to Effect, and III. Arguments from Effect to Effect. All arguments from causal relation may be classed under one or the other of these divisions. These arguments are based upon a fact which human experience has demonstrated to be true—the fact that everything that occurs has back of it some adequate cause. In ancient times this belief in the laws of universal causation did not exist. Hence every occurrence of any importance was attributed to the commands of one of the numerous heathen gods. Instead of attributing the defeat of a general to poor management it was customary to say, “The gods decreed that this general should be defeated in war.”
We still have remnants of this belief. These remnants consist of popular superstitions, such as the supposition that Friday is an unlucky day, that the number thirteen is unlucky, that the breaking of a looking glass portends bad luck, or that the sight of a black cat in the path is sure to be followed by some disaster. Modern science has abolished most of these superstitions by pointing out the fact upon which all causal relation arguments are based, viz.—that everything that happens has back of it a reasonable cause—or in other words, if a thing is true there must be some sufficient reason for it. So well has this fact been established that, with the exception of the less enlightened members ofsociety, the belief in the laws of causation is universal. Upon this sound basis must every argument find its ultimate justification. Even inductions and deductions may be traced to their source where the law of cause and effect will finally determine their validity. It is therefore of the utmost importance that we give careful consideration to this class of arguments. As in the case of imperfect induction, we are reasoning from the known to the unknown; from things of which we are conscious to things that are beyond the realm of our perception. We shall consider the form of these arguments and the conditions with which they must comply in order to be valid.
The argument from effect to cause is one which relies upon an observed effect to prove the operation of an unobserved cause. Upon arising in the morning I observe that the ground which was bare the evening before is now white with snow. Therefore I reason that snow must have fallen during the night, although no snow is now falling and I have not seen any snow in the actual process of falling. The snow-covered ground is the effect which I observe and the unobserved fall of snow during the night is the only possible cause for this effect. If a friend who has not yet seen the snow disputes my assertion that there was a snowfall during the night by saying that it is too warm to snow, I may effectively establish my argument and refute his own by calling him to the window and pointing to the snow. I should point to the effect as establishing the existence of the cause. This would be conclusive evidence of the truth of my statement.
The argument from effect to cause is based upon things observed after the disputed fact. This process is calleda posteriorireasoning which means reasoningfrom that which comes after. This is the process of reasoning employed bythe detective in tracing a criminal. The detective by means of skillful observations taken after a crime is committed reasons back to the person who is guilty. The fact that the criminal has usually made an attempt to avoid leaving any traces that may be used as a basis ofa posteriorireasoning makes this process a most interesting one and accounts for much of the popularity of detective stories.
This use of reasoning from effect to cause was first popularized by the detective stories of Edgar Allan Poe and appears to have reached its climax in theAdventures of Sherlock Holmes, the creation of Sir A. Conan Doyle. Sherlock Holmes possesses remarkable powers of observation. He notices that a young lady who calls to see him has finger tips that are slightly spatulate. From this effect he reasons back to the cause and determines that it is the result of much use of the piano. From this and other observations he reasons that the young lady is a musician. He observes that a farmer has a certain kind of mud on his boots and reasons that the man has just come from a particular town near London where such mud is to be found. The certain kind of mud on the farmer’s boots is the effect; the recent presence of the farmer in that particular town near London is the cause. Observing the effect Holmes reasons back to the cause, or in other words, he constructs an argument from effect to cause.
The application of this process of reasoning to the practice of argumentation and debate is easily seen. The politician who says that the high cost of living is due to the growth of monopolies employs an argument from effect (i. e., the high cost of living) to cause (i. e., the growth of monopolies). The minister who declares that the prevalence of drunkenness is due to the licensed saloon expounds an argument from effect (i. e., the prevalence of drunkenness) to cause (i. e., the licensed saloon). The student who asserts that his class duesare excessive because the business of the class is poorly managed uses an argument from effect (i. e., excessive class dues) to cause (i. e., poor management).
In order to be sound an argument from effect to cause must conform to the following requirements:
When the existence of a definite cause is alleged to have produced an observed effect, the burden of proving the sufficiency of that cause rests upon him who asserts its operation. No fault of reasoning is more common than that of regarding an insufficient cause as sufficient. If a man is successful we attribute his success to one quality, such as perseverance; whereas his success may be due to a combination of qualities. There may be a hundred other men who possess more perseverance and yet fail. When a financial panic occurs we attribute it to the rule of a certain political party; whereas the action of that party may have been the smallest of the factors causing the panic. Perseverance may be a quality contributing to success, but perseverance alone is not sufficient to secure success. The action of a political party may aid in producing a panic, but seldom are conditions such that its action alone is sufficient to produce a panic. The question of what is sufficient cause demands the exercise of sound judgment. A fall of three feet would hardly be regarded as a sufficient cause for the death of a man; a fall of one hundred feet would be regarded as sufficient cause for his death. Between these two extremes the individual judgment considering other circumstances connected with such an event, must determine the adequacy of the cause to produce the result in any given case. It is therefore plain that the debater who points to a result as produced by a definite cause must show the adequacy of that cause.
2. No other cause must have intervened between the alleged cause and the effect.
A clear field must be shown for the operation of the alleged cause. This can be done by proving that no other cause could have produced the observed effect. Other causes which might possibly have produced the effect must be shown to have been inoperative or inadequate. For example, a student fails in his studies. He is called before the delinquent board of the faculty and explains his failure by arguing that he has had poor health. He alleges poor health as the cause of the observed effect—the failure in his studies. A member of the board, however, is skeptical regarding the validity of the argument and asks him if it is not true that each week he attends the theatre at least once and sometimes as often as four times. The student is forced to admit that such is the case. Further inquiry reveals the fact that he has been attending a dancing school one night each week; that he belongs to a club which meets every Tuesday and Friday night; and that he is known to spend much of his time in a public billiard room. These facts show an independent cause (i. e., general dissipation) which has intervened between the alleged cause (i. e., poor health) and the effect (i. e., failure in his studies). The student has therefore failed to prove his argument that poor health, which is a legitimate cause, is responsible for his failure. The evidence shows that general dissipation, which is not a legitimate cause, has intervened between the alleged cause and the effect.
If the student had been able to show that he had been diligent in his efforts, had attended to business in a reasonable manner, and that his previous record had been satisfactory he would have established his argument that ill health was the cause of his failure. In every argument from effect to cause the adequacy of the alleged cause must first be shown and then evidence must be produced establishing the factthat no cause, other than the one alleged, produced the effect.
As stated in the preceding section the alleged cause must have a clear field for action. Not only must no other cause have intervened to produce the effect attributed to the alleged cause, but no forces must have intervened to prevent the alleged cause from operating. Any circumstance which appears to have prevented the operation of the alleged cause should be examined carefully. One morning a man was found dead near the railroad. As there were some bruises on his body, the cause of his death was attributed to his being struck by a local freight which passed that point at midnight. No other train passed over this road at night and the man had been killed sometime within six or eight hours of the time when he was found. The case seemed clear. The result (death) was apparently due to the alleged cause (a freight train). Investigation, however, revealed the fact that the freight train had not run that night on account of a wreck on a branch line. Therefore an outside force,—viz., the wreck, had prevented the alleged cause from operating. Hence it could not be the true cause. The inquiry into the alleged cause ultimately resulted in the revealing of the true cause—willful murder.
In arguing from effect to cause the adequacy of the alleged cause must be proved, the fact that no other cause intervened between the alleged cause and the observed effect must be clearly demonstrated, and the circumstances of the case must show that the alleged cause was not prevented from operating. With these requirements fulfilled such an argument may be regarded as sound. It will be seen that the application of these rules requires sound judgment and practical common sense. The argument will be effective in persuadingothers only when every requirement is met in a plain, straightforward manner.
The argument from cause to effect is one which relies upon an observed cause to prove or foretell the existence of an unobserved effect. For example, I observe that the temperature is very low; the thermometer registers below zero and the exposed parts of my body tingle with cold when I am out of doors. This is a cause of several effects. One of them is that the pond near my home will be frozen over. I observe the cause (i. e., the low temperature) and at once state the effect (i. e., the ice on the pond). The process by which I reached this conclusion is calleda priorireasoning. The conclusion is based upon circumstances observed before the disputed fact. Likewise, I observe that it is now beginning to rain and that appearances indicate a heavy downpour. I at once come to the conclusion that the path across the meadow will be muddy when I pass over it in half an hour from now.
This case differs from the preceding one only in the fact that in the first case the effect existed when the cause was observed, whereas in the latter case the effect did not exist when the cause was observed. In both cases the observed cause is the basis for determining the unobserved effect. In this way we may reason from the past to the present, from the remote past to the less remote past, from the present to the future, from the near future to the more remote future, or from the past to the future.
The student will doubtless have observed that the argument from cause to effect as well as that from effect to cause is a special form of deduction. The syllogistic form may be applied to either of these processes of reasoning for the purpose of testing their strength. Applying the syllogistic formto thea priorireasoning involved in one of the preceding illustrations we have:
A. Low temperature is always followed by the forming of ice.
B. This is low temperature.
C. Therefore it is followed by the forming of ice.
Applying the syllogistic form to thea posteriorireasoning involved in one of the examples given under the discussion of that process we have:
A. All times when the ground is covered with snow are times when there has been a snowfall.
B. This is a time when the ground is covered with snow.
C. Therefore this is a time when there has been a snowfall.
For the purpose of extreme simplicity we may represent these two processes by the following formula:
I.A posteriorireasoning.
1. A isprecededby B
2. This is A
3. Therefore it is preceded by B.
II.A priorireasoning.
1. A isfollowedby B
2. This is A
3. Therefore it is followed by B.
The advocates of a high protective tariff argue that if the tariff is removed financial disaster will overwhelm the country. They support this contention by showing that the large manufacturing industries are now able to sell their products at a reasonable price; import duties prevent foreign manufacturers from shipping their goods into this country and selling them much cheaper than our manufacturers can make them. But if the tariff is removed foreign made goods willdrive out American made goods, as the foreign goods can be sold much cheaper. Therefore factories and mills must cease operations because there will be no demand for their products. Workmen will be thrown out of employment and capital will be idle. Starvation will overtake the working man and financial ruin will overtake the business man. This is a typical example of an argument from cause to effect. The operation of the cause (the removal of the protective tariff) will produce the alleged effect (industrial disaster). This argument appears to be valid, but an equally plausible argument may be constructed against protection. We must, therefore, look at the foundations of each argument for the purpose of determining its validity. As in the case of argument from effect to cause we must exercise sound judgment in applying certain requirements to each particular argument. An argument from cause to effect must conform to the following requirements:
This requirement implies absolute sufficiency of cause, not probable sufficiency. Habitual inattention to business or professional duties is a sure cause for failure. Habitual drunkenness is a sure cause for ill health. Being run over by a locomotive is a sure cause of death. There may be some exceptions to the above general rules, but the certainty of the effect following the cause is so great that for all practical purposes we may rely absolutely upon the sequence.
An observed cause may possibly have an alleged effect even though there is not one chance in a thousand that it will have this effect. No valid argument can be constructedupon such a chance. In pure science this rule is absolute. A combination of the same chemicals under the same conditions always produces the same effect. The bringing of a magnet near a piece of steel always results in the same effect so far as the force which one exerts upon the other is concerned. When we depart from the realm of exact science the working out of the rule becomes less certain. Nevertheless, if human experience has sanctioned the adoption of the rule we may rely upon it even though there are exceptions. A rise in the tax rate is always followed by more revenue to the government. A scarcity in the supply of iron is always followed by a rise in the price. A drouth in the wheat belt is always followed by an increase in the price of flour. There may be exceptions to these examples, but the exceptions are so few and the number of instances supporting the rule is so great that we feel safe in relying upon it. It is this kind of certainty, rather than the absolute certainty of science, which argumentation demands.
A drouth in the wheat belt naturally causes an advance in the price of flour. Past experience has proved this to be the case, and, furthermore, the cause is adequate to produce the alleged effect. Nevertheless, a lowering of the duty on wheat might permit wheat from foreign countries to be imported in such quantities that there would be no rise in the price of flour. The lowering of the duty on wheat would be another force intervening to prevent the observed cause (the drouth in the wheat belt) from producing the alleged effect (the rise in the price of flour). Therefore we must always examine the circumstances of each case to determine whether there are any forces at work which will prevent the observed cause from producing the alleged effect.
4. The conclusion established should be verified by positive evidence wherever possible.
After all the other tests have been satisfied the argument from cause to effect may be established or overthrown by the production of positive evidence. A disappears and B is accused of his murder. A perfect case is made out and B is convicted and sentenced to death. Then A suddenly appears. The innocence of B is effectively established. Cases of this kind are not unknown to the criminal law, though unfortunately the missing man is usually discovered after his supposed murderer has been put to death. This illustration suggests that too much care cannot be exercised in substantiating an argument from cause to effect.
The argument from cause to effect is most frequently employed in criminal trials. In such cases the motive for committing the crime is regarded as the cause and the crime as the effect. The argument is usually begun by proving the existence of strong motives such as an abnormal desire to acquire more money or property, to work revenge on bitter enemies, or to avert financial or domestic disaster. With these strong motives shown it is easy to connect them with the crime. This is the method of argument from cause to effect which is used by Daniel Webster in the White murder trial. He showed clearly that the Knapps believed that they could obtain the fortune of White by destroying his last will and murdering him. He argued that this was the cause which produced the effect of murder. The following extract from Webster’s speech before the jury will show the application made of the argument from cause to effect.
“When we look back, then, to the state of things immediately on the discovery of the murder, we see that suspicion would naturally turn at once, not to the heirs at law, but to those principally benefited by the will. They, and they alone, would be supposed to have a direct object for wishing Mr.White’s life terminated. And, strange as it may seem, we find counsel now insisting, that, if no apology, it is yet mitigation of the atrocity of the Knapps’ conduct in attempting to charge this foul murder on Mr. White, the nephew and principal devisee, that public suspicion was already so directed. As if assassination of character were excusable in proportion as circumstances may render it easy. Their endeavors, when they knew they were suspected themselves, to fix the charge on others, by foul means and by falsehood, are fair and strong proof of their own guilt.
“The counsel say that they might safely admit that Richard Crowninshield, Jr., was the perpetrator of this murder.
“But how could they safely admit that? If that were admitted everything else would follow. For why should Richard Crowninshield, Jr., kill Mr. White? He was not his heir; nor was he his devisee; nor his enemy. What could be his motive? If Richard Crowninshield, Jr., killed Mr. White he did it at some one’s procurement who himself had a motive. And who having any motive, is shown to have had any intercourse with Richard Crowninshield, Jr., but Joseph Knapp and this principally through the agency of the prisoner at the bar? It is the infirmity, the distressing difficulty of the prisoner’s case, that his counsel cannot and dare not admit what they yet cannot disprove, and what all must believe. He who believes, on this evidence, that Richard Crowninshield, Jr., was the immediate murderer cannot doubt that both the Knapps were conspirators in that murder.”
An argument from effect to effect is one in which an argument from effect to cause is combined with an argument from cause to effect. To illustrate this kind of argument we may explain a simple example frequently used in this connection.A boy announces that there is skating this morning because the thermometer registers below zero. Now the thermometer registering below zero is not the cause of the skating. Both the registering of the thermometer and the skating are the effects of a common cause, viz.—low temperature. The boy has observed one of the effects and at once concludes that the other effect must exist. His is an argument from effect to effect, or to be more exact, an argument from one effect of a cause to another effect of the same cause. The whole process of reasoning involved as well as the relation between the two parts of an argument from effect to effect may be represented by the following tabulation:
A. Argument from effect to cause.
1. All times when the thermometer registers below zero are times when the temperature is far below freezing.
2. This is a time when the thermometer registers below zero.
3. Therefore this is a time when the temperature is far below freezing.
B. Argument from cause to effect.
1. All times when the temperature is far below freezing are times when skating ice is formed.
2. This is a time when the temperature is far below freezing.
3. Therefore this is a time when skating ice is formed.
The above analysis of the reasoning involved in an argument from effect to effect will suggest the method of procedure to be employed in testing its validity. The first step consists of dividing the argument into the two essential processes employed, viz.—argument from effect to cause, and argument from cause to effect. The second step consists of applying the rules already considered in connection with each of these processes to the parts revealed by the first step. In this way the validity of any argument from effect to effect may be determined.
SUMMARY OF THE REQUIREMENTS FOR ARGUMENTS FROM CAUSAL RELATION
SUMMARY OF THE REQUIREMENTS FOR ARGUMENTS FROM CAUSAL RELATION
SUMMARY OF THE REQUIREMENTS FOR ARGUMENTS FROM CAUSAL RELATION
I. Arguments from Effect to Cause.
1. The alleged cause must be sufficient to produce the effect.
2. No other cause must have intervened between the alleged cause and the effect.
3. The alleged cause must not have been prevented from operating.
II. Argument from Cause to Effect.
1. The observed cause must be sufficient to produce the alleged effect.
2. When past experience is invoked it must show that the alleged effect has always followed the observed cause.
3. No other force must intervene to prevent the observed cause from operating to produce the alleged effect.
4. The conclusion established should be verified by positive evidence wherever possible.
III. Argument from Effect to Effect.
1. The argument must be resolved into its two parts, the argument from effect to cause, and the argument from cause to effect, and the rules under I and II applied.
EXERCISES IN ARGUMENT FROM CAUSAL RELATION
EXERCISES IN ARGUMENT FROM CAUSAL RELATION
EXERCISES IN ARGUMENT FROM CAUSAL RELATION
I. State the kind of argument involved in each of the following passages.
1. If a Socialist president is elected, financial disaster is sure to overtake our country.
2. This has been the coldest winter ever known in the United States. The rapid destruction of our forests is directly responsible for this undesirable change of climate and we are to reap still further evils from this same cause.
3. Since we have conclusive proof that the savages of the island have murdered this missionary, we can no longer be in doubt as to what became of his companions.
4. “Every word uttered by a speaker costs him some physical loss; and in the strictest sense, he burns that others may have light—so much eloquence, so much of his body resolved into carbonic acid, water and urea.”—Huxley.
5. “The Constitution of the United States is so concise and so general in its terms, that even had America been asslowly moving a country as China, many questions must have arisen on the interpretation of the fundamental law which would have modified its aspect. But America has been the most swiftly expanding of all countries. Hence the questions that have presented themselves have often related to matters which the framers of the Constitution could not have contemplated. Wiser than Justinian before them or Napoleon after them, they foresaw that their work would need to be elucidated by a judicial commentary. But they were far from conjecturing the enormous strain to which some of their expressions would be subjected in the effort to apply them to new facts.”—Bryce.
6. “The last cause of this disobedient spirit in the colonies is hardly less powerful than the rest, as it is not merely moral but laid deep in the natural constitution of things. Three thousand miles of ocean lie between you and them. No contrivance can prevent the effect of this distance in weakening government. Seas roll and months pass, between the order and the execution; and the want of a speedy explanation of a single point is enough to defeat a whole system.”—Burke.
7. “Permit me, Sir, to add another circumstance in our colonies, which contributes no mean part towards the growth and effect of this untractable spirit. I mean their education. In no country perhaps in the world is the law so general a study. The profession itself is numerous and powerful; and in most provinces it takes the lead. The greater number of the deputies sent to the Congress were lawyers. But all who read (and most do read), endeavor to obtain some smattering in that science. I have been told by an eminent bookseller, that in no branch of his business, after tracts of popular devotion, were so many books as those on the law exported to the plantations. The colonists have now fallen into the way of printing them for their own use. I hear that they have sold nearly as many of Blackstone’sCommentariesin America as in England. General Gage marks out this disposition very particularly in a letter on your table. He states that all the people in his government are lawyers, or smatterers in the law; and that in Bostonthey have been enabled, by successful chicane, wholly to evade many parts of one of your capital penal constitutions. The smartness of debate will say that this knowledge ought to teach them more clearly the rights of legislature, their obligation to obedience, and the penalties of rebellion. All this is mighty well. But my honorable and learned friend on the floor, who condescends to mark what I say for animadversion, will disdain that ground. He has heard, as well as I, that when great honors and great emoluments do not win over this knowledge to the service of the State, it is a formidable adversary to Government. If the spirit be not tamed and broken by these happy methods, it is stubborn and litigious.Abeunt studia in mores.This study renders men acute, inquisitive, dexterous, prompt in attack, ready in defence, full of resources. In other countries, the people, more simple, and of a less mercurial cast, judge of an ill principle in government only by an actual grievance; here they anticipate the evil, and judge of the pressure of the grievance by the badness of the principle. They augur misgovernment at a distance; and snuff the approach of tyranny in every tainted breeze.”—Burke.
II. Attach definite circumstances to each of the foregoing arguments and then apply the requirements for validity to each one. State the results.
III. Point out the kind of reasoning which may be employed in reaching each of the following conclusions.
1. The record of our debating teams as compared with that of our opponents shows that we shall win this debate.
2. Harold Small has been put on probation.
3. Under these conditions an inheritance tax should be levied.
4. International arbitration will ultimately take the place of war as a method of settling disputes between nations.
IV. Analyze completely the reasoning processes employed in Exercise III. Where they may be reduced to syllogistic form, determine the validity of the resulting syllogisms.
V. Write an argument from causal relation in support of any proposition which you wish to discuss. Employ each of the three classes of argument from causal relation.
CHAPTER IVARGUMENT FROM ANALOGY
Analogy is such a resemblance between some of the known characteristics of two different things as will lead to the conclusion that they are alike in other characteristics. For example, an egg and a seed are two different things but they have many characteristics in common. From the characteristics in which we know that an egg is like a seed we reason that they must be alike in other characteristics which we know one to possess but which we do not know the other to possess. We know that heat is required to develop an egg and by analogy we may conclude that heat is required to develop a seed. In this, as in other forms of reasoning, we proceed from the known to the unknown. The basis of inference is the general resemblance which one thing bears to another thing. Experience has led us to expect that when we find two different things alike in many points we shall find them alike in many other points regarding which no actual investigation has been made.
The argument applies the principle above suggested to the subject-matter of the discussion. The standard illustration of this form of argument usually quoted in books of logic and argumentation is found in Reid’sIntellectual Powers. It is as follows:—
“We may observe a very great similitude between this earth which we inhabit, and the other planets, Saturn, Jupiter, Mars, Venus, and Mercury. They all revolve around the sun, as the earth does, although at different distances and at different periods. They borrow all their light from thesun, as the earth does. Several of them are known to revolve on their axis like the earth, and by that means have like succession of day and night. Some of them have moons that serve to give them light in the absence of the sun, as our moon does to us. They are all in their motions subject to the same law of gravitation as the earth is. From all this similitude it is not unreasonable to think that these planets may, like our earth, be the habitation of various orders of living creatures. There is some probability in this conclusion from analogy.”
Another frequently quoted illustration of the argument from analogy is the reply of Abraham Lincoln to those who urged him to carry on the war more vigorously.
“Gentlemen, I want you to suppose a case for a moment. Suppose that all the property you were worth was in gold, and you had put it in the hands of Blondin, the famous rope-walker, to carry across the Niagara Falls on a tight rope. Would you shake the rope while he was passing over it, or keep shouting to him, ‘Blondin, stoop a little more! Go a little faster!’ No, I am sure you would not. You would hold your breath as well as your tongue, and keep your hands off until he was safely over. Now the government is in the same situation. It is carrying an immense weight across a stormy ocean. Untold treasures are in its hands. It is doing the best it can. Don’t badger it! Just keep still and it will get you safely over.”
The argument from analogy is most effective when a comparison is made to something that is plain, ordinary, and commonplace. In this way abstract arguments may be made simple and concrete. No debater of modern times has shown more discrimination in the use of material which would make an analogy strong and convincing than has Lincoln. The strength of the argument is greatly increased if it is apparent that the analogy is perfect so far as the pointat issue is concerned. In the following quotation no exercise of the imagination is necessary to bring the two factors of the analogy together. The argument is presented by David Dudley Field in favor of the training of homeless children by the state.
“The question of safety is more vital still. Every one of these boys may be a voter in ten or twenty years hence. His vote will then be as potent as yours or mine. In countries where the sovereign is a prince it has ever been thought prudent to bestow especial care upon the training of an heir to the throne.—Here the people are sovereign, and the little boy, now wandering about the streets, neglected or led astray, is in one sense joint heir to the throne. Every dictate of prudence points to his being fitted to fulfill the duties of his station.”
The foregoing examples with the accompanying explanations will serve to make plain the meaning of argument from analogy and to suggest the innumerable circumstances under which it may be used. Seldom is a situation encountered in which an apt analogy cannot be employed. The homelier the comparison, the more vivid and lasting will be the impression conveyed, provided, of course, that the analogy is apt and appropriate.
The search for an appropriate analogy is best begun by gaining a clear conception of the universal principle upon which the proposition is based. The student must be able to see the broadest application of the reason which he offers in support of any particular contention. Having grasped this fundamental principle it is easy to see its application in other things of a more tangible form and which are more familiar to the average mind. For example, Lincoln saw that it would not do to pursue the Civil War too vigorously. He realized that the government was in a very perilous position, that every step must be taken with care and deliberationand that the least disturbance from those whose interests were at stake might mean failure and the loss of everything. This was the principle underlying the situation which he was facing. Now, he must make this situation plain and its gravity clear to those who were demanding that he hasten the progress of the war. Therefore he began looking for the application of this principle in something which was more familiar and more real and tangible. The newspapers had been full of the wonderful feats of Blondin, the rope-walker. In this circumstance Lincoln saw an opportunity to give a tangible exhibition of the application of the principle under which he was acting.
The argument from analogy which he constructed is a model of completeness. He compared abstract things which could not be seen and appreciated with tangible things which could be seen and appreciated. He compared the Government to Blondin. Blondin, walking on a rope across Niagara Falls, was in a very dangerous position where it was necessary that he move slowly and cautiously because the least misstep would dash him to destruction. The situation of the government was analogous. It was engaged in a very dangerous undertaking, a great civil war. It had to move slowly and cautiously because the least misstep would mean destruction. In order to make the analogy more complete Lincoln supposed the case of Blondin performing this feat carrying with him all the worldly possessions of the men who were urging that the war be pushed more vigorously. The government was carrying out the dearest desire of the people, the patriotic desire to save the grandest of all nations. If the government failed it would mean the blighting of their dearest hopes and to many it would mean financial ruin. Therefore the analogy was complete in that particular. Now these men were here in Washington doing the same thing to the government that they would be doing if, under the above circumstances, theyshook the rope or scolded Blondin while he was walking across Niagara Falls. The forcibleness of the analogy and the vividness of the impression which it conveyed was an argument powerful enough to silence those who were demanding more aggressive action on the part of the government.
An argument from analogy is never conclusive proof of the truth or falsity of a proposition. At best it creates only a high degree of probability. Its greatest use is to give force and vividness to an argument already established by other means. Nevertheless, its probative value is great provided it is properly constructed. The chance for error, however, is a constant source of danger to him who relies upon analogy, for the very facts upon which it is based may constitute the reason for its falsity. A large oil refining company was recently organized. People were induced to buy stock in the new enterprise by means of argument from analogy. It was argued that this company was similar to the Standard Oil Company. Now it is well known that the Standard Oil Company pays large dividends. The argument was advanced by the promoters of the new organization that since it was similar to the Standard Oil Company and since the latter corporation pays large dividends, therefore the new corporation would pay large dividends. The analogy, of course, proved untrustworthy. The companies, though similar in many ways, were entirely different in one essential particular effecting the conclusion: the old company had entirely monopolized the field of activity, while the new company had no territory in which to work. Thus a false analogy led to the loss of many thousands of dollars.
Instances of unsound arguments from analogy might be multiplied indefinitely. It is therefore evident that certain requirements exist which must be strictly complied with if the argument from analogy is to prove effective. The requirementsnecessary for a valid argument from analogy are as follows:
The two factors in the analogy are the thing about which the analogy is made and the thing to which it is compared. For example, in the argument from analogy which we have quoted from Lincoln, the first factor is the position of the government during the Civil War and the second factor is the rope-walker. The former is the thing about which the argument is made; the latter is the thing to which the first factor is compared. These two parts exist in every argument from analogy and the first requirement is that they agree in everything which affects the conclusion. The conclusion Lincoln wished to establish was that the government must not be disturbed in its action because it was in a dangerous position. A rope-walker crossing Niagara Falls must not be disturbed because he is in a dangerous position. These are the facts which affect the conclusion in each case. The two factors are alike in this particular.
From the above example it will be seen that the two factors must agree in the essential particulars. What is essential depends upon the nature of the conclusion to be reached. In particulars affecting things other than the conclusion to be established, it matters not whether they agree or disagree. In comparing an illegal private monopoly to a highwayman the particular method of robbing the victim is immaterial. The fact that the two methods are not exactly alike does not weaken the force of the analogy.
Burke made use of the argument from analogy in defending the policy of conciliation which he favored. After urging that the colonies be granted representation in Parliament, he declared that so far as government was concerned therewere four similar cases,—Ireland, Wales, Chester, and Durham. He urged that the acts of Parliament with regard to these territories be applied to America. He then proceeded to show that the analogy was sound by pointing out that the two factors agreed in all particulars which affected the conclusion. He said,
“Are not the people of America as much Englishmen as the Welsh? The preamble of the Act of Henry the Eighth says the Welsh speak a language no way resembling that of his Majesty’s English subjects. Are the Americans not as numerous? If we may trust the learned and accurate Judge Barrington’s account of North Wales, and take that as a standard to measure the rest there is no comparison. The people cannot amount to above 200,000, not a tenth part of the number in the colonies. Is America in rebellion? Wales was hardly ever free from it. Have you attempted to govern America by penal statutes? You made fifteen for Wales. But your legislative authority is perfect with regard to America. Was it less perfect in Wales, Chester, and Durham? But America is virtually represented. What! does the electric force of virtual representation more easily pass over the Atlantic than pervade Wales, which lies in your neighborhood—or than Chester and Durham, surrounded by an abundance of representation that is actual and palpable? But, Sir, your ancestors thought this sort of virtual representation, however complete, to be totally insufficient for the freedom of inhabitants of territories that are so near and comparatively so inconsiderable. How then can I think it sufficient for those which are infinitely greater and infinitely more remote?”
It will be observed that there is a slight difference in the analogy here employed and the one of which Lincoln made use. In the latter the factors are entirely unlike, in the former they are similar. In all analogies similar to that employedby Burke the points of similarity in the two factors must be clearly shown to bear directly upon the conclusion, whereas if any points of difference exist they must be shown to have no vital bearing on the question at issue.
A failure to observe this application of the rule was made by a student who argued that because an income tax had worked well in other countries it would work well in the United States. His opponent pointed out the unsoundness of the analogy by showing that the income tax proposed for the United States was a progressive tax, whereas the income tax in the foreign countries cited was not a progressive tax. He further revealed the falsity of the analogy by showing that the proposed income tax for the United States was to be levied by the national or Federal government, whereas the income tax in the foreign countries cited was levied by the states or smaller governmental units of those countries. The analogy was shown to be false in that the two factors did not agree in all particulars affecting the conclusion because (1) in one factor the tax was progressive while in the other it was not, and (2) in one factor the tax was levied by the national government and in the other it was not.
The argument from analogy can be made stronger if it is shown that what is true of the analogous case is much more likely to be true and to be true in a greater degree, of the case in dispute. The example of analogy quoted from Burke shows this phase of the process. Some writers call this process an intensification of the argument from analogy. In logic it isa fortiorireasoning. The Scriptures abound in this kind of argument, such as “Are not two sparrows sold for a farthing? and one of them shall not fall on the ground without your Father. Fear ye not therefore; ye are of more value than many sparrows.” Another passage illustrating the intensification of the argument from analogy is, “Consider the ravens; for they neither sow nor reap; which neither havestorehouse nor barn; and God feedeth them; how much more are ye better than the fowls?”
In a debate on the proposition, “Resolved, that courses of instruction in the care and training of children should form a part of the curriculum of every college and university,” a speaker for the affirmative developed an analogy based upon the similarity between such a course and the practical courses in the College of Agriculture on the raising of live stock. He then gave force to his analogy by suggesting that if it were worth while to give college courses dealing with the raising of colts, calves, and pigs, it certainly would be much more worth while to give courses dealing with the raising of children.
The facts alleged to be true in regard to each of the factors in the analogy must be true as a matter of fact. A deviation from the truth in either factor will invalidate the conclusion. In arguing in favor of the municipal ownership and operation of the street railway system in an eastern city a debater declared that the proposed plan would be successful because it had been tried in Chicago with great success. He then spent much time in showing that so far as street railway ownership was concerned conditions in the two cities were exactly alike. This argument from analogy, however, was promptly overthrown by the next speaker, who introduced evidence which proved that the city of Chicago did not own its street railway system. The analogy was unsound because one of the alleged facts upon which it was based was not true.
The above example illustrates one of the chief sources of error in the use of this class of argument. The student must be constantly on his guard when inspecting his own work and that of his opponent. The argument from analogy demandsextensive and accurate knowledge of both the factors involved and the result is almost always in favor of him whose knowledge of the subject-matter is the most comprehensive. The temptation to color the facts in order to fit the analogy is sometimes great and to refrain from deceiving one’s self as well as one’s hearers requires a high degree of intellectual honesty. In no other form of argument is the demand for absolute impartiality more imperative. An analogy which extends beyond the sound foundation of real facts is a constant source of danger both for him who proposes it and for him who receives it. All the alleged facts upon which this kind of argument is based must be true.
The suggestion has already been made that no matter how perfect an analogy may be, it can never amount to absolute proof. At its best analogy creates only a high degree of probability. In order to strengthen the conclusion a diligent search should be made for other lines of reasoning which will fortify it. One of the most important uses to which analogy may be put is to suggest possible conclusions which may be substantiated by other processes of reasoning, as induction, deduction, or causal relation. If two or more lines of reasoning can be made to support the same conclusion the probability of its truth is greatly strengthened; hence its argumentative value is increased. Where all available processes of reasoning may be made to establish one conclusion the probability of its truth is so strengthened that it amounts to moral certainty, but no cumulation of probabilities can ever amount to absolute certainty.
The fact that analogy must be substantiated by other processes of reasoning should not lead the student to underestimate its importance. The examples and explanationswhich have been given should lead him to appreciate fully the fact that analogy has two well defined uses aside from its value as proof of the truth or falsity of a conclusion. In the first place it is a most important agency in suggesting conclusions which may be verified or discredited by other processes of reasoning. In the second place it affords a most valuable method of stating a case so plainly that even the most ignorant may understand. A striking analogy makes a most vivid impression on the mind and is retained long after more formal processes of reasoning are forgotten.