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is derived from the Topics or middle Terms which are used in them, tho* they are called an Address to our Judgment, our Faith, our Ignorance, our Profession, our Modesty, and 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 adjudicium.
2. When it is borrowed from some convincing Testimony, it is 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 profest 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 profest Principles. St. Paul often uses this Argument when he reasons with the Jews, and when he fays, / 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 Paffiones, an Address to the Passions; or if it be made publickly, 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 Premisses. An Argument is called uniform when both the Premisses are derived from the fame Springs of Knowledge, whether it be Sense, Reason, Consciousness, human Faith, or divine Faith: But when the two Premisses 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 Premisses 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 Logick, 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 difagree 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.
The Do&rine of Sophisms.
FROM Truth nothing can really follow but what is true: Whensoever therefore we find a false Conclusion drawn from Premisses which seem to be true, there must be some Fault in the Deduction or Inference; or else one of the Premisses 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.
Os several Kinds of Sophisms, and their Solution.
AS the Rules of right Judgment and of good Ratiocination often coincide with each other, so the Doctrine of Prejudices, which was treated of in the Second Part of Logick, has anticipated a great deal of what might be faid on the Subject of Sophisms; yet I shall mention the most remarkable Springs of false Argumentation, which are reduced by Logicians to some of the following Heads.
I. 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, tho' 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 all 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 them true does not refute the others.
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 Spirits, 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 tho' 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 Adverfary 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 Adverfary as tho' they had utterly confuted his Opinion.
It is a Fallacy of the fame kind which a Disputant is guilty of when he finds that his Adverfary is too hard for him, and that he cannot fairly prove the Question first proposed; he then with Slyness and Subtilty turns the Discourse aside to some other kindred Point which he can prove, and exults in that new Argument wherein his Opponent never contradicted him.
The Way to prevent this Fallacy is by keeping the Eye fixt 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 os what is not granted; that is, when any Proposition is proved by the fame 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 residesin every Member, which is but the fame Thing in other Words. Or, if a Papist should pretend to prove that his Religion is the only Catholick Religion, and is derived from Christ and hisApostles, because it agrees with the Doctrineof all the Fathers of the Church, all the holy Martyrs, and all the Christian Worldthroughout all Ages: Whereas this is a great Point in Contest, whether their Religion does agree with that of all the Anticnts 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,