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which all future combatants might be furnifhed with arms offenfive and defenfive in every caufe, fo as to leave no room to future generations to invent any thing
The last book of the Topics is a code of the laws according to which a fyllogiftical difputation ought to be managed, both on the part of the affailant and defendant. From which it is evident, that this philofopher trained his disciples to contend, not for truth merely, but for victory.
SECT. 3. Of the book concerning Sophisms.
A fyllogifm which leads to a falfe conclufion, must be vicious, either in matter or form for from true principles nothing but truth can be justly deduced. If the matter be faulty, that is, if either of the premises be falfe, that premise must be denied by the defendant. If the form be faulty, fome rule of fyllogifm is tranfgreffed; and it is the part of the defendant to fhew, what general or special rule it is that is tranfgreffed. So that, if he be an able logician, he will be impregnable in the 3 E 2 defence
defence of truth, and may resist all the attacks of the fophift. But as there are fyllogifms which may feem to be perfect both in matter and form, when they are not really fo, as a piece of money may feem to be good coin when it is adulterate; fuch fallacious fyllogifms are confidered in this treatife, in order to make a defendant more expert in the use of his defenfive weapons.
And here the author, with his ufual magnanimity, attempts to bring all the fallacies that can enter into a fyllogifm under thirteen heads; of which fix lie in the diction or language, and feven not in the diction.
The fallacies in diction are, 1. When an ambiguous word is taken at one time in one fenfe, and at another time in another. 2. When an ambiguous phrase is taken in the fame manner. 3. and 4. are ambiguities in fyntax; when words are conjoined in fyntax that ought to be disjoined; or disjoined when they ought to be conjoined. 5. is an ambiguity in profody, accent, or pronunciation. 6. An ambiguity arifing from fome figure of fpeech.
When a sophism of any of these kinds is tranflated into another language, or even rendered into unambiguous expreffions in the fame language, the fallacy is evident, and the fyllogifm appears to have four
The feven fallacies which are faid not to be in the diction, but in the thing, have their proper names in Greek and in Latin, by which they are distinguished. Without minding their names, we fhall give a brief account of their nature.
1. The first is, Taking an accidental conjunction of things for a natural or neceffary connection: as, when from an accident we infer a property; when from an example we infer a rule; when from a fingle act we infer a habit.
2. Taking that abfolutely which ought to be taken comparatively, or with a certain limitation. The construction of lan
guage often leads into this fallacy: for in all languages, it is common to ufe abfolute terms to fignify things that carry in them fome fecret comparifon; or to use unlimited terms, to fignify what from its nature must be limited.
3. Taking that for the cause of a thing
which is only an occafion, or concomi
4. Begging the question. This is done, when the thing to be proved, or fome thing equivalent, is affumed in the premifes.
5. Mistaking the queftion. When the conclufion of the fyllogifm is not the thing that ought to be proved, but fomething else that is mistaken for it.
6. When that which is not a confequence is mistaken for a confequence; as if, because all Africans are black, it were taken for granted that all blacks are Africans.
7. The laft fallacy lies in propofitions that are complex, and imply two affirmations, whereof one may be true, and the other false; so that whether you grant the propofition, or deny it, you are intangled: as when it is affirmed, that such a man If it be has left off playing the fool. granted, it implies, that he did play the fool formerly. If it be denied, it implies, or feems to imply, that he plays the fool still.
In this enumeration, we ought, in juftice to Ariftotle, to expect only the fallacies incident to categorical fyllogifms.
And I do not find, that the logicians have made any additions to it when taken in this view; although they have given fome other fallacies that are incident to fyllogifms of the hypothetical kind, particularly the fallacy of an incomplete enumeration in disjunctive fyllogifms and dilemmas.
The different fpecies of fophifms above mentioned are not fo precifely defined by Aristotle, or by fubfequent logicians, but that they allow of great latitude in the application; and it is often dubious under what particular fpecies a fophiftical fyllogifm ought to be claffed. We even find the fame example brought under one fpecies by one author, and under another fpecies by another. Nay, what is more ftrange, Ariftotle himself employs a long chapter in proving by a particular induction, that all the feven may be brought under that which we have called mistaking the question, and which is commonly called ignoratio elenchi. And indeed the proof of this is easy, without that laborious detail which Aristotle uses for the purpose: for if you lop off from the conclufion of a fophiftical fyllogifm all that is not fup