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106. Deductive reasoning. The basis of a deductive argumentation is the syllogism. This consists of a set of three propositions, two of which, called the major and minor premises, are joined together in such a way as to admit of the third, called the conclusion, being derived from them.

For example:

(1) All our fellow-men are entitled to

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(3) All whales are mammals

All whales are water animals

Therefore some water animals are
mammals

Major premise
Minor premise

Conclusion

Major premise
Minor premise

Conclusion

Major premise
Minor premise

Conclusion

It will be observed that in each of these syllogisms the two premises together contain but three terms, one term being common to the two, and that of these three terms, two appear again in the conclusion. Thus the conclusion has nothing in it that is not derived from the premises; and if the premises be admitted as true, there is no escape from accepting the conclusion as true also. If we represent the

syllogisms graphically by means of circles, we can see at a glance how the conclusions must follow:

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It must not be supposed that in actual discourse we ordinarily find syllogisms fully expressed, as in the examples given above. As a matter of fact, we seldom find them so expressed. The writer who would stop to make all the minute steps of his reasoning so definite and explicit as that would be considered formal

and pedantic. Reasoning by means of the regular syllogism is the exception rather than the rule. It is the enthymeme or incomplete syllogism that is ordinarily employed; for one or other of the premises is usually a truth so obvious as not to need explicit

statement.

The following enthymemes or incomplete syllogisms will serve as illustrations of the ordinary method of making inferences deductively:

We shall die, for all men are mortal.

Brought up among savages, he could not be expected to know the usages of polite society.

He is an oriental, and therefore cannot appreciate the western point of view.

Plagues and convulsions of nature cannot be interpreted as manifestation of God's anger against the wicked, for they involve the innocent as well as the guilty.

In each of these examples one of the premises is suppressed, it being so obvious that the reader is supposed to supply it for himself. Occasionally, even the conclusion may be omitted, as, for example, in the following:

Every man who voted for that measure is a traitor to his country; and we have the honorable gentleman's own word for it that he cast his vote in its favor.

The beginner needs to be cautioned here, perhaps, against the danger of omitting too much, of taking too much for granted. That which appears perfectly obvious to him may not appear obvious at all

to his readers. Before making any assumptions, therefore, he should examine his premises carefully. Whatever can safely be taken for granted should, of course, be assumed. Whatever is doubtful or apt to be misunderstood, however, should be explained and, if necessary, supported by arguments. It is in this elucidation and establishment of his premises, in fact, that the main work of the argumentative writer lies. Where the premises are universally accepted and the inference is plain, there is little or no need for argument. Argument becomes necessary only where one or other of the premises needs explanation and support.

A passage from Webster's argument in the Dartmouth College case, for example, will illustrate the point. One of the main propositions which Webster sought to establish in this celebrated case was that certain acts of the New Hampshire legislature in amending the charter of Dartmouth College without the consent of the trustees were repugnant to the Constitution of the United States. Briefly outlined, his argument takes the form of the following syllogism:

The Constitution of the United States says that no State shall pass a law impairing the obligation of a contract.

But a charter to a private corporation, such as a college, is essentially a contract.

Therefore the acts of the New Hampshire legislature in question amending the charter of Dartmouth College without the consent of the trustees are repugnant to the Constitution of the United States.

Here the major premise is a clause of the Constitution of the United States, which, of course, is accepted without question. But the minor premise, that is, that a charter is essentially a contract, is not so clear. This premise, therefore, Webster has to establish. In fact, the greater part of his speech is taken up with the establishing of this premise. Slightly condensed, his argument runs as follows:

The plaintiffs contend, in the second place, that the acts in question are repugnant to the tenth section of the first article of the Constitution of the United States. The material words of that section are: "No State shall pass any bill of attainder, ex post facto law, or law impairing the obligation of contracts."

It has already been decided in this court, that a grant is a contract, within the meaning of this provision; and that a grant by a State is also a contract, as much as the grant of an individual. In the case of Fletcher v. Peck this court says: "A contract is a compact between two or more parties, and is either executory or executed. An executory contract is one in which a party binds himself to do, or not to do, a particular thing; such was the law under which the conveyance was made by the government. A contract executed is one in which the object of contract is performed; and this, says Blackstone, differs in nothing from a grant. The contract between Georgia and the purchasers was executed by the grant. A contract executed, as well as one which is executory, contains obligations binding on the parties. A grant, in its own nature, amounts to an extinguishment of the right of the grantor, and implies a contract not to re-assert that right. If, under a fair construction of the Constitution, grants are comprehended under the term contracts, is a grant from

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