CHAPTER II

DEDUCTIVE ARGUMENT

Deductive argument consists of the application of deductive processes of reasoning to argumentative discourse. This process of applying logical principles is somewhat more complicated than that involved in induction. In some respects it is more important that the student thoroughly master deduction than it is that he master induction. Fallacies are more easily concealed in the deductive process than in the inductive process. Nevertheless, when the fallacy is once detected it can be set forth clearly by anyone who understands this form of reasoning. Neither the inductive nor the deductive form of reasoning is often found alone. Most arguments contain both of these processes and in some cases they are very closely interwoven. This fact necessitates a thorough study of both processes. From this standpoint a knowledge of one form is as important as a knowledge of the other. In order that we may thoroughly understand the application of the deductive process to argument we must first consider separately that process of reasoning.

I. Deductive reasoning.

By deductive reasoning we arrive at a conclusion regarding a particular person, event, or thing by reason of our knowledge regarding the whole class to which the particular person, event, or thing belongs. In this sense it is the opposite of induction. We conclude that a particular book is interesting because we know that all the books written by the author of this book are interesting. We may say that deductive reasoning begins where inductive reasoning leaves off. For example, we found that we could arrive at the imperfect inductive conclusion that all of Stevenson’s books are interesting because each one of a number of his books which we had read was interesting. Since (1) the number of specific instances cited were sufficient to offset the probability of coincidence, (2) the class was fairly homogeneous, (3) the examples were fair, (4) we found upon investigation that there were no exceptions, and (5) from the character of the author and other circumstances the conclusion seemed reasonable, we concluded that our induction was sound. Now, taking this conclusion as true we may apply it to any one of Stevenson’s works not yet examined and thus determine that that work is interesting. It must be kept in mind, however, that a deduction based upon an imperfect induction is no stronger than that imperfect induction. The imperfect induction gains no strength by reason of its having a valid deduction based upon it. Nevertheless, unsound arguments are often given a superficial appearance of validity by this means.

We may more clearly indicate the relation of the inductive and the deductive process by arranging the material of the foregoing illustration in the following manner.

_A. Inductive process._

1. Specific instances.

(1) _Treasure Island_, written by Stevenson is interesting.

(2) _Kidnapped_, written by Stevenson is interesting.

(3) _David Balfour_, written by Stevenson is interesting.

(4) _Prince Otto_, written by Stevenson is interesting.

(5) _St. Ives_, written by Stevenson is interesting.

2. Conclusion: All books written by Stevenson are interesting.

_B. Deductive process._

1. Major Premise: All books written by Stevenson are interesting.

2. Minor Premise: _The Silverado Squatters_ was written by Stevenson.

3. Conclusion: Therefore _The Silverado Squatters_ is interesting.

It will be observed that the inductive conclusion forms the first statement, the basis, or what is called in logic, the major premise of the deductive process. By induction we build several specific instances into a conclusion, and from that conclusion we reason down again to one particular instance. This illustration should serve to make plain to the student the relation between induction and deduction and the reason why the two processes are so often combined in an argument.

In logic the deductive form presented above is called a syllogism. It consists of three statements called Major Premise, Minor Premise, and Conclusion. This syllogism occurs in different forms, but we are concerned with only the typical form above presented, because it is to this form that we intend to reduce our own arguments and the arguments of our opponents in order that we may test their validity.

Each statement in a syllogism is composed of two parts, called terms. The names of these terms as well as their proper location in the syllogism are indicated by the following form:

Middle term. │ Major term. —————————————————————│——————————————————————————— 1. Major Premise: All college men │should study argumentation.

Minor term. │ Middle term. —————————————————————│——————————————————————————— 2. Minor Premise: Paul Morton │ is a college man.

Minor term. │ Major term. —————————————————————│——————————————————————————— 3. Conclusion: Therefore Paul Morton│should study argumentation.

The student will observe that each statement in the syllogism is composed of two terms and that each term appears twice in the entire syllogism, but only once in any one statement. The major term represents the largest element in the syllogism namely,—the class of persons who should study argumentation. The minor term represents the smallest element in the syllogism namely,—Paul Morton, the particular person about whom a conclusion is reached. The middle term serves as an intermediary or connecting link which binds the minor term to the major term. It does not appear in the conclusion but is cast away after it has served its purpose in assigning the minor term,—Paul Morton, to the major term,—those who should study argumentation.

In the typical form of the syllogism with which we are concerned the major premise should always be in the universal affirmative-form. By universal affirmative is meant that the assertion is made with regard to the class as a whole as: “All men are mortal,” “All laws should be obeyed,” “All students should pay their bills,” etc. No part of the class of persons, events, or things about which an assertion is made should be left outside the statement as would be the case if the statements read—“Some laws should be obeyed,” “Some students should pay their bills.”

From the foregoing discussion it is evident that the deductive syllogism, in order to be valid, must be constructed in accordance with certain well defined rules. In books of logic the student will find these rules discussed at some length and their application set forth in detail. For our purpose it is only necessary to refer to them and keep them clearly in mind in connection with the discussion here given. The rules of the syllogism with which we are concerned are as follows:

1. A syllogism must contain three terms, Major term, Minor term, and Middle term.

2. A syllogism must consist of three complete statements, Major Premise, Minor Premise, and Conclusion.

3. The middle term must be distributed at least once in the premises. A term is distributed when it is universal in its application or taken in its whole length of meaning.

4. A term cannot be distributed in the conclusion unless it is distributed in the premises.

5. No conclusion can be drawn from two negative premises.

6. A negative conclusion always follows one negative premise and a negative conclusion cannot be obtained unless one of the premises is negative.

For the purpose of making more plain the relation between the terms and the statements in a syllogism let us consider the old method of graphical representation by means of circles.

I. All college men should study argumentation.

II. Paul Morton is a college man.

III. Paul Morton should study argumentation.

From the diagrams on the following page it is seen that in the major premise the middle term must be wholly included within the major term. The entire class of college men must be included within the class of those who should study argumentation. Not one single college man must be left outside the class. In the minor premise the minor term must be clearly and unmistakably included within the middle term. Paul Morton must be a college man. He must not be a banker or a janitor. In the conclusion the minor term must be included within the major term. This position inevitably results from the two preceding situations. If the middle term, college men, is wholly included within the major term, those who should study argumentation, and if the minor term, Paul Morton, is wholly included within the middle term, college men, then it cannot be otherwise than that the minor term is included within the major term. In other words, Paul Morton is definitely assigned to the class of those who should study argumentation.

We may represent the whole syllogism in the following manner:

The student should be sure that he has mastered each step in the construction of a valid syllogism of the typical form before he passes on to the following section of this chapter.

II. The application of deductive reasoning to deductive argument.

From our examination of the deductive process of reasoning we cannot but realize its importance when applied to the construction of an argument. One cannot advance far into any argumentative discourse without encountering deduction in some form. A student in a class debate defended the following proposition with the inductive arguments given below: “Resolved that tariff should be imposed for revenue only.” In his introduction the student declared that the protective tariff should be removed. In support of his contention he offered five substantial reasons which he claimed included the vital points at issue. These reasons were as follows:

A. High duties encourage the formation of trusts.

B. The high cost of living results from protection.

C. Protection is unjust to the American people.

D. Protection breeds corruption.

E. The usefulness of the protective tariff has long ceased.

Each of the above reasons for the removal of the protective tariff is a deductive argument. The complete deductive process is seen when we state each argument in syllogistic form.

A

1. All things which encourage the formation of trusts should be abolished.

2. The protective tariff encourages the formation of trusts.

3. Therefore the protective tariff should be abolished.

B

1. All things which are the cause of the high cost of living should be abolished.

2. The protective tariff is a cause of the high cost of living.

3. Therefore the protective tariff should be abolished.

C

1. All things which are unjust to the American people should be abolished.

2. The protective tariff is unjust to the American people.

3. Therefore the protective tariff should be abolished.

D

1. All things which breed corruption should be abolished.

2. The protective tariff breeds corruption.

3. Therefore the protective tariff should be abolished.

E

1. All governmental policies the usefulness of which has long since ceased should be abolished.

2. The protective tariff is a governmental policy the usefulness of which has long since ceased.

3. Therefore the protective tariff should be abolished.

Each of the above syllogisms stands as an argument for the abolition of the protective tariff; or, to take the standpoint of the proposition each supports the contention that the tariff should be imposed for revenue only. All of the five reasons lead to a single conclusion. We may represent this relation by the following diagram:

A B C D E ↓ ↓ ↓ ↓ ↓ CONCLUSION: The protective tariff should be abolished.

This use of deductions is very simple, but in dealing with a combination of induction and deduction the process may become very complicated. For example, the major premise of the first syllogism above stated has back of it another logical process of reasoning. Why should all things which encourage the formation of trusts be abolished? What proof can we show to establish the conclusion (in A, the major premise) that the formation of trusts should be discouraged rather than encouraged? It must be established in a logical manner. We may establish it by induction by showing that each one of a large number of trusts has had injurious effects. After we have introduced positive evidence establishing a perfect or an imperfect induction we have laid a sufficiently strong foundation for the deductive syllogism.

On the other hand, we may establish the major premise of the above syllogism by means of deduction. To do this we might find evidence which would prove that trusts increase the cost of producing commodities and decrease their quality. In this case it would be necessary to introduce evidence only along the line which would show that this evil was characteristic of all trusts. This would be an induction, because the general principle used as a major premise would be based upon specific instances. Beginning with this induction we would build up the following syllogism, the conclusion of which supports the major premise of the foregoing syllogism.

1. All forms of business organization which increase the cost of producing commodities and decrease their quality are an industrial evil.

2. The trust is a form of business organization which increases the cost of production and decreases the quality of commodities.

3. Therefore the trust is an industrial evil.

Then to continue our deductive reasoning we would construct the following syllogism based upon the foregoing:

1. All industrial evils should be discouraged.

2. The formation of trusts is an industrial evil.

3. Therefore the formation of trusts should be discouraged.

The exact phraseology has not been kept throughout the above line of reasoning, because seldom in any practical work do we find the exact words repeated except for emphasis. However, it requires the exercise of only ordinary ingenuity to follow precisely the entire reasoning processes involved in the foregoing argument.

An excellent example of the use of the deductive syllogism for the purpose of showing that an opponent’s deductive argument is unsound is the following extract from Lincoln’s reply to Douglas in the Fifth Joint Debate at Galesburg:

“In the second clause of the sixth article, I believe it is, of the Constitution of the United States we find the following language, ‘This Constitution and the laws of the United States which shall be made in pursuance thereof, and all the treaties made, or which shall be made under the authority of the United States, shall be the supreme law of the land; and the judges in every state shall be bound thereby, anything in the Constitution or laws of any state to the contrary notwithstanding.

“The essence of the Dred Scott case is compressed into the sentence which I will now read, ‘Now as we have already said in an earlier part of this opinion, upon a different point, the right of property in a slave is distinctly and expressly affirmed in the Constitution.’ I repeat it, ‘_The right of property in a slave is distinctly expressed and affirmed in the Constitution_.’ What is it to be ‘affirmed in the Constitution? Made firm in the Constitution,—so made that it cannot be separated from the Constitution without breaking the Constitution; durable as the Constitution, and part of the Constitution. Now remembering the provision of the Constitution which I have read; affirming that that instrument is the supreme law of the land; that the Judges of every state shall be bound by it, any law or constitution of any state to the contrary, notwithstanding; that the right of property in a slave is affirmed in that Constitution, is made, formed into, and cannot be separated from it without breaking it; durable as the instrument; part of the instrument; what follows as a short and even syllogistic argument from it? I think it follows, and I submit to the consideration of men capable of arguing whether as I state it, in syllogistic form, the argument has any faults in it? (1) Nothing in the constitution or laws of any state can destroy a right distinctly and expressly affirmed in the Constitution of the United States. (2) The right of property in a slave is distinctly and expressly affirmed in the Constitution of the United States. (3) Therefore nothing in the Constitution or laws of any state can destroy the right of property in a slave.

“I believe that no fault can be pointed out in that argument; assuming the truth of the premises, the conclusion, so far as I have capacity at all to understand it, follows inevitably. There is a fault in it as I think, but the fault is not in the reasoning; but the fault in fact is a fault of the premises. I believe that the right of property in a slave is not expressly and distinctly affirmed in the Constitution, and Judge Douglas thinks it is. I believe that the Supreme Court and the advocates of that decision may search in vain for the place in the Constitution where the right of property in a slave is distinctly and expressly affirmed. I say, therefore, that I think one of the premises is not true in fact.”

To give examples of all the forms in which deduction may be applied to argument is impossible. The foregoing examples are merely suggestive. They serve to make plain the practical use which can be made of this logical process. The student must master the underlying principles herein suggested and apply them to his own work.

III. The enthymeme.

An enthymeme is an incomplete syllogism. It is a syllogism in which only one or two of the statements are expressed. An example of an enthymeme is the following proposition, “The protective tariff should be abolished because it encourages the formation of trusts.” This is the form in which we most commonly encounter deductive reasoning. Seldom is the complete syllogism expressed. It therefore becomes our task to construct from this enthymeme a complete syllogism. Our first duty, then, is to find out what parts of the syllogism are contained in the enthymeme and then strive to supply the missing parts. Usually the major premise is omitted. This requires that it be supplied from a consideration of the minor premise and the conclusion. In almost all cases the conclusion is expressed. If it is not expressed it is clearly implied. This supplies the minor term (the thing about which something is said) and the major term (the thing that is said about it). From these two terms it is usually easy to find a middle term which will serve as a connecting link. The process of building syllogisms upon enthymemes is comparatively simple if the student will always find the conclusion and then divide it into the two terms of which it is composed.

In order to illustrate the application of the principles above expressed, let us reduce an enthymeme to the syllogistic form. We shall take for our example the enthymeme, “The railroads of the United States should be under Federal control because they are a natural monopoly.” The parts of a syllogism which are expressed in this statement must be found and of these the conclusion should be first determined. In this case the conclusion is “The railroads of the United States should be under Federal control.” “Railroads of the United States,” is the minor term, and “should be under Federal control” is the major term. Now, to represent what we have thus far discovered we apply the order of statements and terms which were employed in the discussion of Deductive Reasoning. The result is as follows:

I. Major Premise: │ Major term ──────────────────────────────────┼──────────────────────────────── │should be under Federal control.

II. Minor Premise: Minor term │ ──────────────────────────────────┼──────────────────────────────── The railroads of the United States│

III. Conclusion:

Minor term │ Major term ──────────────────────────────────┼──────────────────────────────── The railroads of the United States│should be under Federal control.

We thus have the entire syllogism completed with the exception of the middle term. Our next task is to find this middle term. It _must include_ the minor term and it _must be included in_ the major term. A reference to the diagrams given in connection with the discussion of Deductive Reasoning will make this plain. With this requirement in mind we consider the enthymeme and find that the reason assigned for placing railroads under Federal control is that they are a natural monopoly. This gives us the middle term as it appears in the minor premise. We then take this middle term and cast it into the universal affirmative form, “All natural monopolies.” We now have the enthymeme with which we started out, reduced to the following syllogistic form:

Major Premise: All natural monopolies should be under Federal control.

Minor Premise: The railroads of the United States are a natural monopoly.

Conclusion: Therefore the railroads of the United States should be under Federal control.

This places clearly before us the deductive argument contained in the enthymeme. The syllogism is complete. The statements and terms are in their proper order and form, and the conclusion follows logically and inevitably from the premises. The form of the syllogism as it stands is therefore sound. If the two premises are true as a matter of fact, the conclusion must be true. Having determined these matters we now scrutinize each of the premises to see whether there is sufficient evidence to establish its truth. In the first place is it true that all natural monopolies should be under Federal control? What is a natural monopoly and why should it be under Federal control? All the sources of evidence must be searched for facts and statements of authority to substantiate this assertion. On this point opinions differ and the student must strive to find out the truth for himself. The other question which he must answer is, “Are the railroads of the United States a natural monopoly?” Here again the student must resort to the sources of evidence and by their aid answer the question in the affirmative or in the negative. If he can introduce enough evidence to prove that all natural monopolies in the United States should be under Federal control, and that the railroads are a natural monopoly, then he has completed a sound deductive argument in favor of the Federal control of railroads. This example ought to make clear the method of reducing an enthymeme to the syllogistic form and the use to which this form may then be put.

Before leaving this subject a word of caution is necessary. Do not be confused by the form in which the enthymeme appears. Be sure that you have the real conclusion before you begin the construction of the rest of the syllogism. If you have failed to grasp what the enthymeme really says you are liable to get a wrong conclusion, and if you get a wrong conclusion the whole syllogism will be wrong. High sounding oratorical phrases and sentences are often confusing. Plainness is sometimes avoided by the speaker for the express purpose of concealing a fault in his argument. Even truth expressed in an unusual form is often misleading when we seek to reduce it to logical terms.

Some difficulty is usually experienced in reducing the beatitudes to the typical syllogistic form. For example, in reducing the enthymeme “Blessed are the pure in heart, for they shall see God,” the inexperienced student usually says that the conclusion is, “The blessed shall see God.” A syllogism built upon this conclusion would appear as follows:

1. All those who are pure in heart shall see God.

2. The blessed are pure in heart.

3. Therefore the blessed shall see God.

This is a valid syllogism so far as the form is concerned; but it is of no use in throwing light upon the truth or falsity of the enthymeme, because the conclusion with which we started was not the true conclusion. This fault is fatal to the success of the argument, because after the syllogism is completed the student usually devotes his entire attention to proving the truth or falsity of the two premises and seldom gives any further attention to the conclusion.

Another erroneous statement of the conclusion expressed in the above enthymeme is often given. It is “All those who are blessed shall see God.” With this conclusion as a starting point we may construct the following syllogism:

1. All those who are blessed shall see God.

2. The pure in heart are blessed.

3. Therefore the pure in heart shall see God.

Again we have an invalid syllogism, because the conclusion from which we built it is not the true conclusion expressed in the enthymeme. Likewise there are many pitfalls for him who seeks to find the true meaning of any statement worded in a manner different from that in which we are accustomed to speak. The very difficulty, however, suggests the remedy. The student should always reduce the complicated statement to plain, ordinary, everyday English before attempting to find the conclusion. Reducing the enthymeme under consideration in this manner we have this simple statement, “The pure in heart are blessed because they shall see God.” When we have put the statement in this form the real conclusion is readily seen. It is “The pure in heart are blessed.” The remainder of the enthymeme is a statement of the reason why the pure in heart are blessed. With this as a basis we easily construct a valid syllogism.

1. All those who shall see God are blessed.

2. The pure in heart shall see God.

3. Therefore the pure in heart are blessed.

In closing this discussion it may be remarked that actual practice in the use of the deductive process as well as its application to argument is the only way in which real practical benefit may be derived from the knowledge here gained. This knowledge should not be reserved for use in the class room but should be used all the time and everywhere.

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.