[386] Ibid. ii. p. 157, a. 18-33. διὸ πειρατέον ἐπὶ πάντων τῶν τοιούτων ὀνοματοποιεῖν αὐτόν, &c.
If the respondent answers in the affirmative to several questions of similar particulars, but answers in the negative when you sum them up in an universal comprehending all similar cases, — you may require him to cite some particular case justifying his denial; though you cannot require him to do this before he has made the affirmative answers.[387] It is not sufficient that he should cite, as the single case of exception, the express case which forms the subject of the thesis: He ought to produce some distinct and independent instance, really comprised within the genus, and not merely connected with it by the link of an equivocal term.[388] If he produces an adverse instance really comprised within the genus, you may perhaps be able to re-model your question, so as to make reserve for the basis on which this objection is founded. The respondent will then be compelled (unless he can foresee some new case of objection) to concede the universal with this special qualification; so that you will have gained all that you really require. Should the respondent continue to refuse, without producing any new case, he will transgress the rules of Dialectic; which recognize an universal affirmative, wherever there are numerous affirmative particulars without one assignable negative.[389] Indeed, if you know the universal to hold in many particular cases, and do not know of any others adverse, you may boldly put your question at once in reference to the universal (without going first through the series of particulars). The respondent will hardly venture to deny it, not having in his mind any negative particulars.[390]
[387] Ibid. a. 34-37.
[388] Ibid. a. 37-b. 8.
[389] Topic. VIII. ix. p. 1577, b. 8-33. διαλεκτικὴ γάρ ἐστι πρότασις πρὸς ἣν οὕτως ἐπὶ πολλῶν ἔχουσαν μὴ ἔστιν ἔνστασις.
[390] Ibid. p. 158, a. 3-6.
You must however keep in mind what a dialectic universal premiss really is. Not every question requiring an universal answer is allowed to be put. You must not ask for positive information, nor put such questions as the following: What is man? In how many different senses is good employed? A dialectic question is one to which the respondent makes sufficient reply by saying, Yes or No.[391] You must ask in this form: Is the definition of man so and so? Is good enunciated in this or that different sense? To these questions the respondent may answer Yes or No. But if he persists in negative answers to your multiplied questions as to this or that sense of the term good, you may perhaps stand excused for asking him: “In how many different senses, then, do you yourself use the term good?�[392]
[391] Ibid. p. 158, a. 14, seq. ἔστι γὰρ πρότασις διαλεκτικὴ πρὸς ἣν ἔστιν ἀποκρίνασθαι ναὶ ἢ οὔ.
[392] Ibid. a. 21-24.
When you have obtained concessions which furnish premisses for a formal syllogism, you will draw out and propound that syllogism and its conclusion forthwith, without asking any farther question from the respondent or any leave from him to do so. He may indeed deny your right to do this, in spite of the concessions which he has made; and the auditors around, not fully appreciating all his concessions, may perhaps think that he is entitled to deny it. But, if you ask his leave to draw out the syllogism and he refuses to give leave, the auditors are much more likely to think that your syllogism is not allowable.[393] If you have the choice between an ostensive syllogism and a Reductio ad Absurdum, you ought always to prefer the former, as plainer and more incontestable.[394]