CHAPTER IV

ARGUMENT 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's Intellectual 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 the

sun, 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.

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'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 ropewalker, 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 point

at 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 delibera

tion and 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, they

shook 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 re