In exemplification of the expository method as applied to Moral Suasion, we may refer to Extract XVI.

91. Persuasion is aided by all the arts that can strengthen or loosen the bonds which fasten ideas in the mind.

This appears to open a large subject, but, in point of fact, it only refers us to the figures and devices of style already considered. Similes, metaphors, antitheses, epigrams, balanced constructions, have all the effect of strengthening the hold of certain things upon the mind, and thereby increasing their force when used in persuasion. Bacon's epigram, "By indignities men come to dignities," tends to dissolve the usual associations with indignity, and replace them with others of a contrary nature. The metaphor that "Calumny is the shadow of greatness," has a similar efficacy in modifying our views of calumny. The apothegm, "Youth in toil, age in ease," by its form, deepens a moral impression.

Canning's famous retort to the Irish repealers, is an argument intensified by the form of the language:-"Repeal the Union, restore the Heptarchy."

92. II. Persuasion takes on, to a large extent, the form of Argument, Reasoning, or Proof.

There are still supposed certain fundamental dispositions, convictions, or opinions on the part of the hearers, accompanied with ability and readiness to follow trains of reasoning or deductions from these, and to balance considerations on opposite sides.

Argumentative Persuasion is closely allied with Logical Proof (See EXPOSITION by PROOF). To a mind perfectly ra tional, scientific or logical evidence is conviction; Logic and Rhetoric are the same. But the ordinary arts of persuasive reasoning take in modes of proceeding irrelevant to genuine proof, and adapted to minds imperfectly rational.

All Proof and all Disproof are resolvable into allegations of Similarity or Dissimilarity. To comply with the demands

of logic, the alleged similarities must be complete and relevant; and so with the dissimilarities: but for persuasion, it is enough that they appear so to the persons addressed.

Before commencing to argue a question, the speaker is recommended to set clearly before his own mind the point to be argued. The arts of exposition contain all the artificial means of furthering this object. In an argument intended to satisfy minds of fair intelligence, the leading terms should be defined, and the principles expressed in clear language, with the aid of counter-statement and example.

93. An Argument is a fact, principle, or set of facts or of principles, adduced as evidence of some other fact or principle.

It is alleged as a fact, or a law of nature, that the stars gravitate towards each other; and the argument, or fact in proof, is that the sun and planets gravitate. We argue that the weather is about to change, by quoting the fact that the barometer is falling, or the fact that the wind is shifting, or the general law that at the particular season such changes happen.

94. Two things are requisite in Argument. First: The facts or principles adduced must be admitted, and sufficiently believed in, by the hearers.

Belief may be genuine, but too feeble to overcome resistance.

95. Secondly: A certain similarity must be admitted to hold between the facts or principles adduced and the point to be established.

One fact cannot prove another unless the two are so far of a kind, that, on the ground of nature's uniformity, we may expeet the second to happen exactly as the first has happened. The gravitation of the sun and planets is an argument for the gravitation of the stars, because we believe that the stars are constituted with a sufficient amount of likeness to entail the gravitating property, nature being uniform.

Of the two requisites just mentioned, the first corresponds

to the major premise of the Logical Syllogism, the second to the minor. The major (in a regular syllogism of the first Figure) lays down a principle, the minor asserts the relevance or identity of this with the thing to be proved. "Matter gravitates (major)—a meteoric stone is matter (minor)—a meteoric stone gravitates." Mr. J. S. Mill has shown that the major need not be a general principle; it may be a fact or series of facts stated individually; "this, that, and the other material thing gravitates (major): a certain thing-a meteor-resembles these in their common property of being inert matter; and so (nature being uniform) resembles them in the superadded property of gravitating."

96: Arguments, or Proofs, are of the following classes:-(1.) Deductive, Necessary, or Implicated; that is, such as imply the thing to be proved.

An assertion given to accredit its obverse, is an argument of implication or necessity. It is merely viewing the same fact from the other side, and is little more than a change of language. "Such a race cannot be savages; for they have many civilized institutions." "Virtue favors happiness; vice causes misery."

The logical converse of an assertion (made by transposing the subject and predicate with certain cautions) is the exact equivalent of the original, and is therefore a case of mere implication. "No just man would make his children a burden. to others; no one that does this is just,"—are different forms of the same assertion, and not different assertions; and to make the one prove the other is to put forward an argument of impli

cation.

When a general statement is advanced as evidence of a particular included in it, the argument is deductive or implicated: "We shall die, for all men are mortal." The syllogism, as already remarked, is of this character; the major premise covers the conclusion, provided we have assurance of the relevancy, as affirmed in the minor. It has only to be ascertained that we are men (the minor); and the argument to prove that we shall

DEDUCTIVE PROOFS.

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die is necessary, because it contains the fact as a part of the meaning.

This form of deductive argument is a prevailing type of argumentative reasoning. The mode of expressing it is a kind of inverted exposition; instead of a general doctrine taking the lead of the particular examples or applications, a particular case is given first, and the principle is then adduced as the proof of it. To show that the Laplanders are not so miserable as we should expect from their climate, we bring forward the general principle that the mind of man shapes itself to his condition.

Another well-known type of deductive reasoning, consists in following out a conditional assertion. "If the moon has no atmosphere, animals constituted like those on the earth cannot exist there (major); now the moon has no atmosphere (minor); therefore animals constituted like those on the earth do not exist in the moon."

97. (2.) Inductive, sometimes called Contingent: as when from particulars observed, known, or admitted, we prove, through the medium of nature's uniformity, other particulars unobserved, unknown, or unadmitted.

The argument for the gravitation of the stars is inductive. The proof that quinine will cure ague is of the same class.

Although a knowledge of the various modes of Inductive proof, as they are exhibited in Mill's Logic of Induction, would serve the purposes of exposition and persuasion, as well as of science, I cannot transfer a complete enumeration of these to the present work. A few select points may, nevertheless, be indicated.

The first species of Inductive proof is called the Method of Agreement. It is grounded on the uniform companionship of two facts through a great variety of circumstances, which leads to their being considered as cause and effect. We should prove by this method that extreme heat is a cause of deterioration of the human system; for, under all varieties of race and of individual character, a residence in the tropics is accompanied with enfeeblement of body, or of mind, or of both.

It is only a scientific man, or a logician, that is fully aware of the limits of this argument; the popular tendency is to accept it too easily: it has a rhetorical plausibility beyond its real worth.

Many common modes of reasoning are fallacious examples of this canon. A particular mode of life is called healthy, because it has been the habit of a healthy man; a certain institution is lauded, because a nation has prospered under it. The logician in such instances would say that the conditions of a true induction have not been complied with. The easiest mode of disabusing an ordinary mind, is to produce instances where the same thing has been present without the same effect.

It adds greatly to the force of conviction by this method, as well as to its genuine cogency, to combine cases of agreement in absence with agreement in presence. Thus the effects of political liberty are more fully certified by comparing a number of countries where it exists with others where it does not exist.

The other leading mode of establishing cause and effect is called the Method of Difference. When a man, in the fulness of life, is shot and falls lifeless, we know that the shot killed him, because that agency made the whole difference between his living and his dying. When a red-hot wire is immersed in oxygen gas, it bursts into a flame and is rapidly consumed. The contact with pure oxygen is the only difference that we have made in the circumstances of the wire, and that contact is thereby proved to be the cause of the combustion. When a nation suddenly rises to prosperity on the accession of a new minister, like the British people under Chatham, no other important change having occurred, we infer that he is the cause of the improvement.

The Method of Difference furnishes a more decided proof of causation than the Method of Agreement. It is hence often resorted to in argument, and not unfrequently abused; being put forward in cases where the difference is not reduced to the one single circumstance alleged.

A third mode of Inductive proof is a variety of the foregoing, called the Method of Residues. We take away from a