Authors/Ockham/Summa Logicae/Book III-1/Chapter 5

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[Cap. 5 Ad videndum quando syllogismus regulatur per dici de omni et de nullo et quando non] [Chapter 5.  For seeing when a syllogism is governed by the dici de omni and when not]
Quando autem syllogismus non regulatur per dici de omni vel de nullo, tunc non oportet quod valeat, sed est fallacia accidentis vel aliqua alia fallacia. Ad videndum autem quando discursus non regulatur per dici de omni nec de nullo intelligendae sunt ad praesens regulae infra scriptae. Now when a syllogism is not governed by the dici de omni, then it does not have to be valid, but is rather a fallacy of accident or some other fallacy.  For seeing when a discourse is not governed by the dici de omni, the rules below should at be understood for the present purposes.
(1) Prima est quod quandocumque minor habet aliquam exponentem negativam talis discursus non potest regulari per dici de omni vel de nullo. Et ratio est quia, sicut dictum et prius, per maiorem non denotatur nisi quod de quocumque dicitur subiectum quod de eodem dicitur praedicatum, vel ab eo removetur. Igitur si in minori denotetur subiectum removeri ab aliquo, vel aliquid aliud removeri ab aliquo, nullo modo poterit regulari per dici de omni vel de nullo, quia in minori non debet denotari nisi quod subiectum primae propositionis dicitur de aliquo. Et ita patet manifeste quod quando minor habet aliquam exponentem negativam, non poterit syllogismus regulari per dici de omni vel de nullo. The first is that whenever the minor premiss has some negative exponent, such a discourse cannot be governed by the dici de omni. And the reason is that, as said before, by the major premiss it is only denoted that of whatever the subject is said, the predicate is predicated of the same thing (or removed from it).  Therefore, if in the minor premiss it is denoted that the subject is removed from something, or some other thing is removed from something, it could in no way be governed by the dici de omni, for in the minor premiss it should only be denoted that the subject of the first proposition is said of something.  And so it is manifestly clear that when the minor has some negative exponent, the syllogism could not be governed by the dici de omni.
Per istam regulam excluduntur propositiones exclusivae et exceptivae et habentes aliquod istorum verborum 'incipit' vel 'desinit', et quaecumgue aliae quae habent exponentes negativas, ne possint esse minores in tali syllogismo. Et ideo talis discursus non valet 'omnis homo est animal; tantum risibile est homo; igitur tantum risibile est animal'; nec talis 'omne album est corpus; omne animal praeter corvum est album; igitur omne animal praeter corvum est corpus'; nec iste 'omne ridens est homo; Sortes incipit esse ridens; igitur Sortes incipit esse homo'; nec talis 'omne sentiens est animal; asinus desinit esse sentiens; igitur asinus desinit esse animal'; et omnes alii habentes consimilem defectum non valent. Through this rule are excluded exclusive and exceptive propositions, and those having one of the words 'begins' or 'ceases', and any other which have negative exponents, nor could they be the minor premisses in such a syllogism.  And therefore such a discourse as "every man is an animal, only something capable of laughter is a man, therefore the only thing capable of laughter is an animal" is not valid, and neither is "every white thing is a body, every animal apart from a crow is white, therefore every animal apart from a crow is a body", nor is "everything laughing is a man, Socrates begins to laugh, therefore Socrates begins to be a man", nor "everything sentient is an animal, a donkey ceases to be sentient, therefore a donkey ceases to be an animal", and all others having a similar defect are not valid.
(2) Alia regula est quod quandocumque in minori propositione denotatur praedicatum dici de subiecto cum aliquo modo, nato determinare compositionem, non expresso in maiore, qui modus positus et non positus mutat propositionem quantum ad veritatem vel falsitatem, talis discursus non regulatur per dici de omni vel de nullo. Tales autem modi sunt huiusmodi 'necessario', 'contingenter', 'velociter', 'bene', 'male' et cetera adverbia. Nam haec est vera 'homo est albus' et haec est falsa 'homo necessario est albus'. Similiter haec est vera 'homo est albus' et haec est falsa 'homo per se est albus'. Et ita est de multis aliis. Another rule is that whenever in the minor proposition it is denoted that the predicate is said of some subject in some mode, suited to determine composition, that is not expressed in the major, which mode, posited or not posited, changes the proposition in respect of truth and falsity, such a discoure is not governed by the dici de omni.  And such modes are 'necessarily', 'contingently', 'quickly', 'well', 'badly' and the other adverbs. For "a man is white" is true, and "a man is necessarily white" is false.  Similarly "a man is white" is true, and "a man per se is white" is false. And so it is for many others.
Et ratio istius regulae est, quia per propositionem universalem maiorem non denotatur nisi quod de quocumque dicitur subiectum de eodem dicitur praedicatum vel removetur, et non denotatur quod de quocumque dicitur subiectum cum aliquo adverbio determinante compositionem quod de eodem dicitur praedicatum cum eodem adverbio. Et ideo accipere in minore aliquod tale adverbium non est regulare talem syllogismum per dici de omni vel de nullo. Et ideo tales syllogismi non valent 'omnis homo est albus, Sortes necessario est homo; igitur Sortes necessario est albus'. Instantia dicta est prius. Nec tales syllogismi valent 'omnis creans est Deus, quaelibet persona divina contingenter est creans, igitur quaelibet persona divina contingenter est Deus'; 'omne currens est homo; Sortes est velociter currens; ergo Sortes est velociter homo. And the reason for this rule is that through the major universal proposition it is only denoted that of whatever the subject is said, the predicate is said, or is removed, but it is not denoted that of whatever the subject is said with some adverb determining composition, the predicate is said with the same adverb.  And so to accept some such adverb in the minor is not to govern such a syllogism by the dici de omni.  And therefore such syllogisms as "every man is white, Socrates is necessarily a man, therefore Socrates necessarily is white" are not valid. The counterexample was mentioned before.  Nor are such syllogisms as the following valid: "every creator is God, any divine person contingently is a creator, therefore any divine person contingently is God", "everything running is a man, Socrates is running quickly, therefore Socrates is quickly a man".
Et est diligenter advertendum an in minore accipiatur aliquis terminus includens aequivalenter talem determinationem adverbialem vel aequivalentem, quamvis non exprimatur. Quia si sic, non erit syllogismus regulatus per dici de omni vel de nullo. And it should carefully be noticed whether in the minor some term is accepted equivalently including some adverbial determination or its equivalent, although unexpressed.  For if so, it will not be a syllogism governed by the dici de omni.
(3) Alia regula est quod quando in propositione minori ponitur aliquis modus qui potest competere toti propositioni, si in maiore hoc denotetur, non semper talis discursus regulabitur per dici de omni vel de nullo. Sed quia hoc tangit syllogismos ex modalibus, ideo de hoc dimittatur ad praesens. Another rule is that when in the minor proposition there is given some mode which can belong to the whole proposition, if this is denoted in the major proposition, such a syllogism will not always be governed by the dici de omni. But because this touches on the subject of modal syllogisms, I will leave this out at present.
(4) Alia regula est quod quando per maiorem non denotatur praedicatum vere affirmari vel vere negari de pronomine demonstrante quodcumque quod est realiter idem cum significato per subiectum, tunc accipiendo sub aliquid tale, non erit syllogismus regulatus per dici de omni vel de nullo. Et ideo talis discursus non regulatur per dici de omni 'omnis essentia divina est communis tribus personis; Pater est essentia divina; igitur Pater est communis tribus personis', et hoc quia per istam 'omnis essentia divina est communis tribus personis' non denotatur quod quilibet, qui est essentia divina realiter, sit communis tribus personis, sed praecise denotatur quod quidquid est essentia realiter et formaliter, est commune tribus personis. Et ideo accipiendo sub 'Pater est essentia', nisi acciperetur sic sub 'Pater est essentia realiter et formaliter' non arguitur per dici de omni. Another rule is that when it is not denoted by the major that the predicate is truly affirmed or truly denied of a pronoun demonstrating anything that is really the same with the thing signified by the subject, then by subsuming such a thing, it will not be a syllogism governed by the dici de omni. And therefore such a discourse is not governed by the dici de omni: "every divine essence is common to three persons, the father is a divine essence, therefore the father is common to three persons", and this is because by "every divine essence is common to three persons" it is not denoted that anything which is really a divine essence is common to three persons, but it is precisely denoted that whatever is an essence really and formally, is common to three persons.  And therefore by subsuming "the father is an essence", unless there were subsumed "the father is really and formally an essence", it is not argued according to the dici de omni.
Secus autem est hic 'omnis homo currit; album est homo; igitur album currit, nam per istam 'omnis homo currit' denotatur quod quicumque est homo realiter quod ipse currit, et ideo accipiendo sub 'Sortes est homo' sequitur quod Sortes currit. Non sic autem per istam 'omnis essentia divina est communis tribus personis', quia non denotatur quod quicumque est essentia divina quod est communis tribus personis, hoc enim falsum est. Et ita patet satis evidenter, supposito quod essentia divina unica et singularissima sit tres personae et tamen quod una non sit alia, quomodo iste syllogismus non regulatur per dici de omni 'omnis essentia divina est communis tribus personis; Pater est essentia divina; igitur Pater est communis tribus personis', et tamen iste syllogismus regulatur per dici de omni 'omnis homo currit; album est homo; igitur album currit'. But it is otherwise with "every man runs, a white thing is a man, therefore a white thing runs", for by "every man runs" it is denoted that whatever is really a man, that the man runs, and therefore by subsuming "Socrates is a man", it follows that Socrates runs.  But it is not this way for "every divine essence is common to three persons", for it is not denoted that whatever is a divine essence, that it is common to three persons, for this is false.  And so it is evidently clear enough, supposing that the divine essence, unique and most singular is three persons, and nevertheless that one is not another, in what way the syllogism "every divine essence is common to three persons, the father is a divine essence, therefore the father is common to three persons" is not governed by the dici de omni, and yet the syllogism "every man runs, a white thing is a man, therefore a white thing runs" is governed by the dici de omni.
Est autem sciendum quod quamvis propter rationem dictam nullus discursus, ubi persona accipitur sub essentia vel e converso, reguletur per dici de omni vel de nullo, tamen multi tales valent et tenent et multi non valent. Quando autem talis discursus tenet et quando non, non potest sciri nisi quando in Scriptura Sacra vel ex determinatione Ecclesiae vel ex eis, mediante evidenti syllogismo, habetur quod praemissae sunt verae et conclusio falsa: sicut oportet credere quod omnis essentia divina est Pater, et quod Filius est essentia divina, et tamen quod haec est falsa 'Filius est Pater', et ideo iste discursus non valet 'omnis essentia divina est Pater; Filius est essentia divina; igitur Filius est Pater'. Sed non sic est de isto discursu 'omnis essentia divina fuit scita a philosohis esse immortalis; Pater est essentia divina; igitur Pater fuit scitus a philosophis esse immortalis'. Non enim habentur praemissae in Sacra Scriptora vel ex determinatione Ecclesiae cum opposito conclusionis, nec illa tria evidenter sequuntur ex illis, ideo talis discursus est concedendus. Et universaliter omnis talis discursus est concedendus nisi possit inveniri in Sacra Scriptura vel ex determinatione Ecclesiae vel evidenter sequatur ex talibus quod praemissae sunt verae cum opposito conclusionis. Et ideo talis discursus in creaturis numquam debet negari, quia inter creaturas impossibile est quod una res numero, simplex et singularis, sit realiter plures res distinctae realiter. But it should be known that although, for the reason given above, no discourse is governed by dici de omni where 'person' is accepted under 'essence' and conversely, yet many such discourses are valid, and many are not valid. But when such a discourse holds, and when not, cannot be known except when in sacred scripture or from the determination of the church, or from them, by an intermediary evident syllogism, it is held that the premisses are true and the conclusion false, just as we have to believe that every divine essence is the father, and the the son is a divine essence, and nevertheless that "the son is the father" is false, and therefore the discourse "every divine essence is the father, the son is a divine essence, therefore the son is the father" is not valid.  But it is not the case for this discourse: "every divine essence was known by the philosophers to be immortal, the father is a divine essence, therefore the father was known by the philosophers to be immortal".  For the premisses are not held in sacred scripture or from the determination of the church with the opposite of the conclusion, nor do those three evidently follow from them, therefore such a discourse is to be conceded. And generally every such discourse is to be conceded unless it could be found in sacred scripture or from the determination of the church or it evidently follows from such propositions that the premisses are true with the opposite of the conclusion. And therefore such a discourse in the world of created things should never be denied, for in the world of created things it is impossible that something one in number, simple and singular, really be several things, really distinct.
(5) Alia regula est quod nullus terminus in praemissis vel conclusione sumatur aequivoce. Si enim aliquis terminus, sive in praemissis sive in conclusione, sumatur aequivoce, non poterit regulari per dici de omni vel de nullo. Et ideo talis syllogismus 'omnis canis currit; caeleste sidus est canis; igitur caeleste sidus currit' non regulatur per dici de omni vel de nullo si 'canis' sumatur aequivoce. Nam per istam propositionem 'omnis canis currit' non denotatur quod de quocumque dicitur subiectum quod de eodem dicitur praedicatum, sed denotatur quod de quocumque dicitur hoc subiectum 'canis', quando supponit pro animali latrabili, quod de eodem dicitur praedicatum, et non plus. Et ideo accipere postea quod 'caeleste sidus est canis', accipiendo 'canis' pro caelesti sidere et non pro animali latrabili, non est arguere per dici de omni, sicut clare patet. Et sicut est de istis, ita est de aliis. Another rule is that no term in the premisses or conclusion be taken equivocally.  For if some term, either in the premisses or the conclusion, is taken equivocally, it could not be governed by the dici de omni. And therefore a syllogism such as "every dog runs, a celestial star is a dog, therefore a celestial star runs" is not governed by the dici de omni, if 'dog' is taken equivocally. For by the proposition "every dog runs", it is not denoted that of whatever the subject is said, the predicate is said of the same thing, but rather it is denoted that of whatever the subject 'dog' is said - when it supposits for an animal capable of barking - the predicate is said of the same thing, and no more.  And therefore to accept afterwards that "a celestial star is a dog", in taking 'dog' for a celestial star and not for an animal capable of barking, we are not arguing by the dici de omni, as is evidently clear.  And just as it is for these, so for others.
(6) Alia regula est quod nullum syncategorema, nisi forte signum universale vel particulare additum super subiecto, addatur vel auferatur in minore vel conclusione praeter illa quae sunt in maiore. Et si aliquod tale syncategorema ponatur in maiore, si in illa sit determinatio praedicati, oportet quod in alia propositione, in qua debet poni, sit determinatio praedicati. Si autem sit in illa determinatio compositionis, debet etiam in alia esse determinatio compositionis, quia aliter non regulabitur per dici de omni vel de nullo. Et ideo tales syllogismi non valent 'omnis homo est tantum animal; Sortes est homo; igitur Sortes est tantum animal'. Et multi tales deficiunt propter aliquem defectum tactorum. Another rule is that no syncategorema, unless perhaps it is the universal or the particular sign added to the subject, is added or taken away in the minor or the conclusion, beyond those which are in the minor.  And if some such syncategorema is given in the major, if in that there is a determination of the predicate, it has to be that in another proposition, in which it should be given, there is a determination of the predicate.  But if there is in that proposition a determination of composition, there should also be a determination of composition in the other, for otherwise it will not be governed by the dici de omni.  And therefore syllogisms such as "every man is only an animal, Socrates is a man, therefore Socrates is only an animal" are not valid.  And many such syllogisms are deficient because of some of the defects touched upon.

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