There was a famous ancient instance of this case wherein a Dilemma was retorted. Euathlus promised Protagoras a reward when he had taught him the art of pleading, and it was to be paid the first day that he gained any cause in the court. After a considerable time Protagoras goes to law with Euathlus for the reward, and uses this Dilemma: either the cause will go on my side, or on yours; if the cause goes on my side, you must pay me according to the sentence of the judge: if the cause goes on your side, you must pay me according to your bargain: therefore whether the cause goes for me or against me, you may pay me the reward. But Euathlus retorted this Dilemma thus: either I shall gain the cause or lose it; if I gain the cause, then nothing will be due to you according to the sentence of the judge; but if I lose the cause, nothing will be due to you according to my bargain: therefore whether I gain or lose the cause, I will not pay you, for nothing will be due to you.

Note 1. A Dilemma is usually described as though it always proved the absurdity, inconvenience, or unreasonableness of some opinion or practice; and this is the most common design of it; but it is plain that it may also be used to prove the truth or advantage of any thing proposed; as, in heaven we shall either have desires or not; if we have no desires, then we have full satisfaction; if we have desires, they shall be satisfied as fast as they arise: therefore in heaven we shall be completely satisfied.

Note 2. This sort of argument may be composed of three or four members, and may be called a Trilemma.

III. A Prosyllogism is when two or more syllogisms are so connected together, that the conclusion of the former is the major or minor of the following; as blood cannot think; but the soul of man thinks: therefore the soul of man is not blood; but the soul of a brute is his blood, according to the scripture ; therefore the soul of a man is different from the soul of a brute.-See another instance in the introduction to this treatise, p. 8.

IV. A Sorites is when several middle terms are chosen to connect one another successively in several

propositions, till the last proposition connects its predicate with the first subject. Thus, all men of revenge have their souls often uneasy; uneasy souls are a plague to themselves; now to be one's own plague is folly in the extreme; therefore all men of revenge are extreme fools.

The apostle, Rom. viii. 29, gives us an instance of this sort of argument, if it were reduced to exact form: Whom he foreknew those he predestinated; whom he predestinated he called; whom he called he justified; whom he justified he glorified: therefore whom he foreknew he glorified.

To these syllogisms it may not be improper to add Induction, which is when, from several particular propositions we infer one gene al; as, the doctrine of the Socinians cannot be proved from the Gospel, it cannot be proved from the Acts of the Apostles, it cannot be proved from the Epistles, nor the Book of Revelation; therefore it cannot be proved from the New Testament

Note, this sort of argument is often defective, because there is not due care taken to enumerate all the particulars on which the conclusion should depend.

All these four kinds of syllogisms in this section may be called redundant, because they have more than three pròpositions. But there is one sort of syllogism which is defective, and is called an Enthymema, because only the conclusion with one of the premises is expressed, while the other is supposed and reserved in the mind: thus, there is no true religion without good morals; therefore a knave cannot be truly religious: or thus, it is our duty to love our neighbours as ourselves; therefore there are but few who perform their duty.

Note, this is the most common sort of argument amongst mankind both in writing and in speaking; for it would take up too much time and too much retard the discourse to draw out all our arguments in mood and figure. Besides, mankind love to have so much compliment paid to their understandings as to suppose that they know the major or minor which is suppressed and implied, when you pronounce the other premises and the conclusion.

If there be any debate about this argument, the

syllogism must be completed, in order to try its force and goodness, by adding the absent proposition. SECT. VII-Of the middle Terms, of common Places or Topics, and Invention of Arguments.

The next division of syllogisms is according to the middle term, which is made use of in the proof of any proposition. Now the middle term (as we have hinted before) is often called Argument, because the force of the syllogism depends upon it: we must make a little delay here to treat briefly of the doctrine of topics, or places whence middle terms or arguments are drawn.

All arts and sciences have some general subjects which belong to them, which are called Topics or common places; because middle terms are borrowed, and arguments derived from them for the proof of their various propositions which we have occasion to discourse of. The topics of Grammar are etymology, Houn, verb, construction, signification, &c. The topics of Logic are genus, species, difference, property, definition, division, &c. The topics of Ontology or Metaphysics, are cause, effect, action, passion, indentity, opposition, subject, adjunct, sign, &c. The topics of Morality or Ethics, are law, sin, duty, authority, freedom of will, command, threatening, reward, punishment, &c. The topics of Theology are, God, Christ, faith, hope, worship, salvation, &e.

To these several topics there belong particular observations, axioms, canous, or rules*, which are laid down in their proper sciences; as,

Grammar hath such canon, (viz.) words in a different construction obtain a different sense, words derived from the same primitive may probably have some affinity in their original meaning, &c.

Canons in logic are such as these, every part of a division singly taken must contain less than the whole. A definition must be peculiar and proper to the thing defined. Whatever is affirmed or denied of the genus, may be affirmed or denied of the species, &c.

Metaphysical canons are such as these; final

A canon is a proposition declaring some property of the subject, which is not expressed in the definition or division of it.

causes belong only to intelligent agents. If a natural and necessary cause operate, the effect will follow, &c. and there are large catalogues of many more in each distinct science.

Now it has been the custom of those who teach logic or rhetoric, to direct their disciples, when they want au argument, to consult the several topics which are suited to their subject of discourse, and to rummage over the definitions, divisions, and canous that belong to each topic. This is called the inven tion of an argument, and is taught with much solem nity in some schools.

I grant there may good use of this practice for persons of a lower genius, when they are to compose any discourse for the public; or for those of superior parts to refresh their memory, and revive their acquaintance with a subject which has been long ab. sent from their thoughts, or when their natural spirits labour under indisposition and languor; but when a man of moderate sagacity has made himself master of his theme by just diligence and enquiry, he has seldom need to run knocking at the doors of all the topics, that he may furnish himself with argument or matter of speaking: and indeed it is only a man of sense and judgment that can use common places or topics well; for amongst this variety he only knows what is fit to be left out, as well as what is fit to be spoken.

By some logical writers this business of topics and invention is treated of in such a manner with mathematical figures and diagrams, filled with the barbarous technical words, Napcas, Nipcis, Ropcos, Nosrop, &c. as though an ignorant lad were to be led mechanically in certain artificial harnesses and tram mels to find out arguments to prove or refute any proposition whatsoever, without any rational knowledge of the ideas. Now there is no need to throw words of contempt on such a practice; the very description of it carries reproof and ridicule in abundance.

SECT. VIII. Of several Kinds of Arguments and Demonstrations.

We proceed now to the division of syllogisms according to the middle term; and in this part of our

treatise the syllogisms themselves are properly called arguments, and are thus distributed.

1. Arguments are called Grammatical, Logical, Metaphysical, Physical, Moral, Mechanical, Theological, &c. according to the art, science, or subject, whence the middle term or topic is borrowed. Thus, if we prove that no man should steal from his neighbour, because the scripture forbids it, this is a theological argument; if we prove it from the laws of the land, it is political; but if we prove it from the principles of reason and equity, the argument is moral.

II. Arguments are either certain and evident, or doubtful and merely probable.

Probable arguments are those whose conclusions are proved by some probable medium; as, this hill was once a church-yard, or a field of battle, because there are many human bones found here. This is not a certain argument, for human bones might have been conveyed there some other way.

Evident and certain arguments are called demonstrations; for they prove their conclusions by clear mediums and undoubted principles; and they are generally divided into these two sorts:

I. Demonstrations a priori, which prove the effect by its necessary cause; as, I prove the scripture is infallibly true: because it is the word of God, who cannot lie.

2. Demonstrations a posteriori, which infer the eause from its necessary effects; as, I infer there hath been the hand of some artificer here, because I find a curious engine. Or, I infer there is a God, from the works of his wisdom in the visible world,

The last of these is called "demonstratio Tou OTI," because it proves only the existence of a thing; the first named "demonstratio TOU DIOTE," because it shews also the cause of existence.

But note, that though these two sorts of arguments are most peculiarly called demonstrations, yet generally any strong and convincing argument obtains that name; and it is the custom of mathematicians to call all their arguments demonstrations, from what medium soever they derive them.

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