III. Arguments are divided into artificial and inartificial.

An artificial argument is taken from the nature and circumstances of the things; and if the argument be strong, it produces a natural certainty; as, the world was at first created by God, because nothing can create itself.

An inartificial argument is the testimony of another, and this is called original, when our information proceeds immediately from the persons concerned, or from eye or ear-witnesses of the fact it is called tradition when it is delivered by the report of others.

We have taken notice before, that testimony is either divine or human. If the humau testimony be strong, it produces a moral certainty; but divine testimony produces a supernatural certainty, which is far superior.

Note, Arguments taken from human testimony, as well as from laws and rules of equity, are called moral; and indeed the same name is also applied to every sort of argument which is drawn from the free actions of God, or the contingent actions of men, wherein we cannot arrive at a natural certainty, but content ourselves with an high degree of probability, which in many cases is scarce inferior to natural certainty.

IV. Arguments are either direct or indirect. It is a direct argument where the middle term is such as proves the question itself, and infers that very proposition which was the matter of enquiry. An indirect or oblique argument proves or refutes some other proposition, and thereby makes the thing enquired appear to be true by plain consequence.

Several arguments are called indirect; as, (1.) when some contradictory proposition is proved to be false, improbable or impossible: or when, upon supposition of the falsehood, or denial of the original proposition, some absurdity is inferred. This is called a proof per impossibile, or a reductio ad absurdum. (2.) When some other proposition is proved to be true which is less probable, and thence it follows, that the original proposition is true; because it is more probable. This is an argument ex magis probabili ad minus. (3.)

When any other proposition is proved upon which it was before agreed to yield the original question. This is an argument ex concesso.

V. There is yet another rank of arguments which have Latin names; their true distinction is derived from the topics or middle terms which are used in them, though they are called an address to our judgment, our faith, our ignorance, our profession, our modesty, or our passions.

1. If an argument be taken from the nature or existence of things, and addressed to the reason of mankind, it is called argumentum ad judicium.

2. When it is borrowed from some convincing testimony, it is called argumentum ad fidem, an address to our faith.

3. When it is drawn from any insufficient medium whatsoever, and yet the opposer has not skill to refute or answer it, this is argumentum ad ignorantiam, an address to our ignorance.

4. When it is built upon the professed principles or opinions of the person with whom we argue, whether the opinions be true or false, it is named argumentum ad hominem, an address to our professed principles. St. Paul often uses this argument when he reasons with the Jews, and when he says, I speak as a man.

5. When the argument is fetched from the sentiments of some wise, great, or good men, whose authority we reverence and hardly dare oppose, it is called argumentum ad verecundiam, an address to our modesty.

6. I add finally, when an argument is borrowed from any topics which are suited to engage the inclinations and passions of the hearers on the side of the speaker, rather than to convince the judgment, this is argumentum ad passiones, au address to the passiones: or if it be made publicly, it is called ad populum, or an appeal to the people,

After all these divisions of syllogism or argument arising from the middle term, there is one distinction proper to be mentioned which arises from the premises. An argument is called uniform when both the premises are derived from the same spring of knowledge, whether it be sense, reason, consciousness, hu

man faith, or divine faith. But when the two premises are derived from different springs of knowledge, it is called a mixt argument.

Whether the conclusion must be called human or divine, when one or both premises are matters of divine faith, but the conclusion is drawn by human reason, I leave to be disputed and determined in the schools of theology.

Thus the second chapter is finished, and a particular account given of all the chief kinds of syllogisms or arguments which are made use of among men, or treated of in logic, together with special rules for the formation of them, as far as is necessary.

If a syllogism agree with the rules which are given for the construction and regulation of it, it is called a true argument: if it disagree with these rules, it is a paralogism, or false argument: but when a false argument puts on the face and appearance of a true one, then it is properly called a sophism or fallacy, which shall be the subject of the next chapter.

CHAP. III.

THE DOCTRINE OF SYLLOGISMS.

FROM truth nothing can really follow but what is true; whensoever therefore we find a false conclusion drawn from premises which seem to be true, there must be some fault in the deduction or inference: or else one of the premises is not true in the sense in which it. is used in that argument.

When an argument carries the face of truth with it, and yet leads us into mistake, it is a sophism: and there is some need of a particular description of these fallacious arguments, that we may with more ease and readiness detect and solve them.

SECT. I. Of several Kinds of Sophisms and their Solutions.

As the rules of right judgment and of good ratioci ́nation often coincide with each other, so the doctrine of prejudices, which was treated of in the second part of logic, has anticipated a great deal of what might be said on the subject of sophisms: yet I shall mention the most remarkable springs of false argu

mentation which are reduced by logicians to some o the following heads.

1. The first sort of sophism is called ignoratio elenchi, or a mistake of the question; that is, when something else is proved which has neither any necessary connection or inconsistency with the thing enquired, and consequently gives no determination to the enquiry, though it may seem at first sight to determine the question; as, if any should.conclude that St. Paul was not a native Jew, by proving that he was born a Roman; or if they should pretend to determine that he was neither Roman nor Jew, by proving that he was born at Tarsus in Cilicia: these sophisms are refuted by shewing that these three may be true: for he was born of Jewish parents, in the city of Tarsus, and by some peculiar privilege granted to his parents, or his native city, he was born a denizen of Rome. Thus there is neither of these three characters of the apostle inconsistent with each other, and therefore the proving one of thei true does not refute the other.

Or if the question be proposed, whether excess of wine can be hurtful to him that drinks it, and the sophister should prove that it revives his spirit, it exhilarates his soul, it gives a man courage, and makes him strong and active, and then he takes it for granted that he has proved his point:

But the respondent may easily shew, that though wine may do all this, yet it may be finally hurtful both to the soul and body of him that drinks it to

excess.

Disputers when they grow warm are ready to run into this fallacy; they dress up the opinion of their adversary as they please, and ascribe sentiments to him which he doth not acknowledge, and when they have with a great deal of pomp attacked and confounded these images of straw of their own making, they triumph over their adversary, as though they had utterly confounded his opinion.

It is a fallacy of the same kind which a disputant is guilty of, when he finds that his adversary is too hard for him, and that he cannot fairly prove the question first proposed; he then with slyness and

subtlety turns the discourse aside to some other kindred point which he can prove, and exults in that new argument wherein this opponent never contradicted him.

The way to prevent this fallacy is by keeping the eye fixed on the precise point of dispute, and neither wandering from it ourselves, nor suffering our antagonist to wander from it, or substitute any thing else

in its room.

II. The next sophism is called petitio principii, or a supposition of what is not granted; that is, when any proposition is proved by the same proposition in other words, or by something that is equally uncertain and disputed: as if any one undertake to prove that the human soul is extended through all the parts of the body, because it resides in every member, which is but the same thing in other words. Or, if a Papist should pretend to prove that his religion is the only Catholic religion, and is derived from Christ and his apostles, because it agrees with the doctrine of all the fathers of the church, all the holy martyrs, and all the Christian world throughout all ages: whereas this is a great point in contest, whether their religion does agree with that of all the ancients, and the primitive Christians or no.

III. That sort of fallacy which is called a Circle is very near a-kin to the petitio principii; as, when oue of the premises in a syllogism is questioned and opposed, and we intend to prove it by the conclusion: or, when in a train of syllogisms we prove the last by recurring to what was the conclusion of the first. The Papists are famous at this sort of fallacy, when they prove the scripture to be the word of God by the authority or infallible testimony of their church, and when they are called to shew the infallible authority of their church, they pretend to prove it by the scripture.

IV. The next kind of sophism is called non causa pro causa, or the assignation of a false cause. -- This the Peripatetic philosophers were guilty of continually, when they told us that certain beings, which they called substantial forms, were the springs of colour, motion, vegetation, and the various operations of natural beings in the animate and inanimate world;TM