Monitio logica, or, An abstract and translation of Burgersdicius his logick by a gentleman.

CHAP. XXXII. Of Conversion, Aequipollence, and Sub∣alternation of Enunciations.

Ax. 1. THose Affections are said to be Related, which agree to Enunciations amongst themselves Compared.

Ax. 2. And these are four, viz. Conversion, Aequi∣pollence, Subalternation and Opposition. And,

Ax. 3. Conversion is the Transposition saving the Truth of the Predicate into the Place of the Subject; and the Subject into the Place of the Predicate.

COMMENTARY.

1. §. In which Action the Truth must be saved, because the Conversion is to follow from the Converted. Now this Related Affection of

Ax. 4. Conversion may be divided into Simple, that which is by Accident, and that which is by Con∣traposition.

Ax. 5. Simple's that in which the Quantity and Quality of the Enunciation are preserved.

Ax. 6. And has Place in the Universal Denying, and Particular Affirming: As,

1. §. No Man is a Beast; and therefore no Beast is a Man: Some Man is white; and therefore some∣thing white is a Man, &c.

Ax. 7. By Accident, that in which the Quality being preserv'd, the Quantity is diminished.

Ax. 8. And takes Place in the Universal Affirm∣ing.

1 §. Quantity diminish'd, that is, the Universal is chang'd into a Particular; as, Every Plant lives; and therefore something which lives is a Plant, &c.

Ax. 9. Contraposition, that in which in Place of the Subject and the Predicate is put the Contradiction of them both.

Ax. 10. And has, Place in the Universal Affirm∣ing.

1 §. As every Mortal is generated; and therefore that which is not Generated, is not Mortal, &c.

Ax. 11. The particular Denying is not ordinarily converted.

1. §. For it does not follow, that because some Animal is not a Man, that therefore some Man should not be an Animal, &c. And if a particular Denying be at any time converted; as, some Man is not white, and therefore something white not Man: It is fortuitous, and to be imputed to the Matter: As also that, sometimes a Universal Affirming may be converted, saving the Quantity, to wit, when consist∣ing of Reciprocal Terms: As, every Man is a Ratio∣nal Animal, and therefore every Rational Animal is a Man, &c.

Ax. 12. But it must be observed in Conversion of Enunciations, that the whole Predicate must be changed into Place of the Subject. And likewise whole Subject into the Predicates, or else the Place of the Conversion may be fallacious.

1. §. For Example: This Enunciation, Some Church is in the City, must not be converted into this; Some City is in the Church; but this, Something which is in the City is a Church; because the Predicate of the E∣nunciation to be converted, is not City, but, to be in it. In like manner, the Predicate of this Enuncia∣tion, Every old Man was a Boy's, not only Boy, but was a Boy. And therefore not to be converted into this, viz. Some Boy was an old Man; but this, viz. some one who was a Boy, is an Old Man, &c.

2. §. Now the Conversion of Modals is by means of the Dictum, the Mode still remaining Enunciati∣ons necessary are converted as pure: Universals de∣nying, and Particulars affirming, simply. Univer∣sals affirming either by Accident, or Contraposition; as, It is necessary that every Man should be an Animal; and therefore that some, that is, that some Animal should be a Man; or it is necessary, that that which is not an Animal, should not be a Man, &c.

3 §. One thing is here to be observ'd, that those Enunciations which have the Mode Necessary, be necessary of themselves: For if they have not this Necessity, the Conversion will be false: As, it is ne∣cessary, that every old Man should have been a Boy, and therefore that some one that was a Boy should be an old Man. Every learned Person should have been taught, and therefore that some one who has been taught should be learned, &c. Such Conversions as these do not co∣here; Because that an old Man should have been a Boy, or a learned Man taught, is not necessary of its self, or absolutely, but only of every one, because by the Supernatural Power of God it might have been otherwise, &c. Conversion of Modals in the other Moods can not be prescrib'd by any certain Rules: For those things that Aristotle says in the first Book of Prior. Cap. 3. have more in them of Difficulty than Use.

As to the Aequipollency or like Value of Enuncia∣tions in Sense, which differ in Words, which the Author says something of, I thought it of little Sig∣nificancy to be mentioned here; and therefore I pass'd it by as well that of those differing in Site of the Negative-Particle only, as Mood. The Rules about one and the other being no great Matter; and for that Aequipollencies of this Nature, may easily be discern'd without Rule.

Ax. 13. By Subalternation we express our Mean∣ing when we would signifie that one Enunciation

is subordinated to another, and does necessarily fol∣low from it, but not on the contrary, as Particulars and Singulars from Universals, to which they are indispensably and necessarily subordinate.

1. §. For if every Man is Mortal, then also this or that Man must be sure to be Mortal: And if none, then this or that Man to be sure, is not so, &c.

2. §. In Modals, Subalternation is considered, not only in reference to the Dictum, but to the Mood. Also Subalternation of Dictum is the same in Modals as it is in the Pure: And the Modes of Possible and Contingent, are Subalternated to those of Necessary and Impossible. For Necessary includes the Adverb always; whilst Impossible, never: Which de∣note a Universality of Time. Contingent and Possi∣ble, sometimes, which is a Note of Particularity of Time. And hence come we to the 33 Chapter, viz. That