Authors/Ockham/Summa Logicae/Book II/Chapter 10

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Latin English
[2.10. DE PROPOSITIONIBUS MODALIBUS SINE DICTO] 10: On Modal Propositions without a Dictum
Circa propositiones modales sine dicto propositionis, quae omnino aequipollent propositionibus sumptis cum dicto in sensu divisionis, est sciendum quod tales non convertuntur cum primis; immo potest una illarum esse vera, alia exsistente falsa et e converso. Sicut secundum viam Aristotelis haec est vera in sensu compositionis 'omnem hominem esse animal est necessarium' et tamen haec est falsa 'omnis homo de necessitate est animal'. Similiter, secundum viam Aristotelis, haec est vera 'omne verum esse verum est necessarium', et tamen haec est falsa 'omne verum necessario est verum'. Et ita de multis aliis. Concerning modal propositions without a dictum of a proposition, which are wholly equipollent to propositions taken with a dictum in the sense of division, it should be known that such propositions are not convertible with the first type,[1] indeed one of these can be true with the other false, and conversely. For example, in the way of Aristotle, 'That every man is an animal is necessary' is true in the sense of composition, and yet 'Every man is necessarily an animal' is false. Likewise, in the way of Aristotle, 'That every truth is true is necessary' is true, and yet 'Every truth is necessarily true' is false. And so on for many others.
Propter quod sciendum quod ad veritatem talium propositionum requiritur quod praedicatum sub propria forma competat illi pro quo subiectum supponit, vel pronomini demonstranti illud pro quo subiectum supponit; ita scilicet quod modus expressus in tali propositione vere praedicetur de propositione de inesse, in qua ipsummet praedicatum praedicatur de pronomine demonstrante illud pro quo subiectum supponit, proportionaliter sicut dictum est de propositionibus de praeterito et de futuro. Sicut ad veritatem istius 'omne verum de necessitate est verum' requiritur quod quaelibet propositio sit necessaria in qua hoc praedicatum 'verum' praedicatur de quolibet pro quo hoc subiectum 'verum' supponit, puta quod quaelibet talis sit necessaria 'hoc est verum', 'illud est verum', demonstrato quocumque pro quo subiectum supponit. Et quia non quaelibet talis est vera, ideo haec est simpliciter falsa 'omne verum de necessitate est verum'. Because of this, it should be known that for the truth of such propositions it is required that the predicate under its proper form belongs to that for which the subject supposits, or [belongs] to a pronoun indicating that for which the subject supposits. In other words, so that the mode expressed in such a proposition is truly predicated of an assertoric proposition in which the very same predicate is predicated of a pronoun indicating that for which the subject supposits, as was correspondingly stated [by me] in the case of past-tense and future-tense propositions. For example, for the truth of 'Every truth is necessarily true' it is required that every proposition is necessary in which the predicate 'true' is predicated of anything for which the subject '[a] true [thing]' supposits. For example, it is required that every proposition such as 'This is true', 'That is true', is necessary, indicating something for which the subject supposits. And because not every such proposition is necessary, therefore 'Every truth is necessarily true' is absolutely false.
Similiter per istam 'creans potest non esse Deus' non denotatur quod haec sit possibilis 'creans non est Deus', quia tunc haec esset vera de possibili, sed denotatur quod haec sit possibilis 'hoc non est Deus', demonstrato illo pro quo 'creans' supponit in ista 'creans potest non esse Deus'. Et ista est simpliciter impossibilis, quia 'creans' in ista 'creans potest non esse Deus' supponit pro Deo. Et certe haec est impossibilis 'hoc non est Deus', demonstrato Deo. Similiter per istam 'creans necessario est Deus' denotatur quod haec sit necessaria 'hoc est Deus', demonstrato illo pro quo 'creans' supponit in praedicta propositione de necessario; et hoc est verum. Ideo illa propositio de necessario est vera, non tamen est necessaria, sed est contingenter vera, quia posito quod Deus cessaret creare tunc esset falsa, sicut sua de inesse esset falsa, haec scilicet 'creans est Deus'. Likewise, by 'a creating being can be not God' it is not denoted that 'a being which creates is not God' is possible, because in that case this proposition would be true de possibili, but it is denoted that 'this is not God' is possible, indicating what 'being which creates' supposits for in 'a being which creates can be not God'. And this is simply impossible, because 'creating being' in 'a creating being can be not God' supposits for God. And certainly, 'This is not God', indicating God, is impossible. Likewise, by [the proposition] 'a creating being is necessarily God' it is denoted that 'This is God' is necessary, indicating that for which ' creating being' supposits in the aforesaid de necessario proposition, and this is true. Therefore, that de necessario proposition is true, yet it is not necessary, but is contingently true, because, given that God had ceased to create, then it would then be false, just as its corresponding assertoric [proposition], namely, 'a creating being is God', would be false.
Nec est aliquod inconveniens quod propositio vera de necessario sit contingens, sicut patet in exemplo praedicto. Et sicut propositio vera de necessario potest esse contingens, ita propositio vera per se potest esse vera per accidens et contingenter, sicut haec est vera 'creans per se est Deus', et tamen est per accidens vera et contingenter. Et ita est de multis aliis. Tamen non obstante quod tales sunt verae, tamen tales sunt falsae 'Deus necessario est creans' et tales verae 'Deus contingenter est creans', 'Deus potest non esse creans', 'Deus potest esse non creans' et huiusmodi. Et hoc quia nulla propositio in qua praedicatur hoc praedicatum 'creans' de pronomine demonstrante illud pro quo hic terminus 'Deus' supponit est necessaria sed contingens, quia quaelibet talis est contingens 'hoc est creans', 'hoc est non creans', demonstrando Deum. Nor is it inappropriate that a proposition true de necessario is contingent, as is clear in the aforesaid example. And just as a proposition true de necessario can be contingent, so too a proposition true per se can be true accidentally and contingently, just as 'a creating being per se is God' is true, and yet it is true accidentally and contingently.

And so it is in many other cases. Yet, notwithstanding that such propositions are true, propositions such as 'God is necessarily a creating being' are false and propositions such as these are true: 'God is contingently a creating being', 'God is able not to be a creating being', 'God can be a not creating being', etc. And this is so because no proposition in which the predicate 'creating being' is predicated of a pronoun indicating that for which the term 'God' supposits is necessary, but rather contingent, because every proposition such as 'this is a creating being' and 'that is a non creating being', indicating God, is contingent.

Similiter dicendum est de talibus propositionibus 'Deus potest assumere suppositum humanum', 'Deus potest uniri supposito humano', 'Deus potest se solo facere actum meritorium', 'Deus potest facere album sine albedine' et huiusmodi, quae omnes falsae sunt, quia quaelibet propositio in qua praedicatur aliquod praedictorum de pronomine demonstrante illud pro quo supponit subiectum est simpliciter impossibilis. Nam haec est impossibilis 'suppositum est assumptum'; nam sequitur 'suppositum est assumptum, igitur suppositum innititur alteri', et ultra 'igitur suppositum non est suppositum', et tamen implicatur esse suppositum; igitur haec est impossibilis 'suppositum est assumptum'. Similiter haec est impossibilis 'hoc est unitum supposito', demonstrando Deum. Et ista similiter 'Deus facit se solo actum meritorium', quia sequitur 'Deus facit se solo actum meritorium, ergo actus meritorius non fit nisi a Deo; et per consequens non fit a voluntate cuius est; et per consequens non est actus meritorius'. A similar thing should be said of such propositions as: 'God can assume a human suppositum', 'God can be united to a human suppositum', 'God can bring about a meritorious act by himself, 'God can make a white thing without whiteness', and others of this kind, which are all false, because every proposition in which one of the above is predicated of a pronoun indicating that thing which the subject supposits for is absolutely impossible. For 'a suppositum is assumed' is impossible, for this follows: 'a suppositum is assumed; therefore a suppositum depends upon another'—and further, 'therefore a suppositum is not a suppositum'. But it is implied that it is a suppositum. Therefore, 'A suppositum is assumed' is impossible. Similarly, 'This is united to a suppositum', referring to God, is impossible. Likewise, 'God performs a meritorious act by himself is impossible, and likewise: 'God performs a meritorious act by himself; therefore a meritorious act is performed only by God; consequently, it is not performed by the will of the person whose act it is, and, consequently, it is not a meritorious act'.
Tamen hoc non obstante, nisi aliquis modus logicalis vel grammaticalis impediat, istae sunt verae 'suppositum potest assumi a Verbo', 'suppositum potest uniri Verbo', 'actus meritorius potest fieri a solo Deo', quia per nullam istarum denotatur nisi quod propositio in qua praedicatur praedicatum de pronomine demonstrante illud pro quo subiectum supponit sit possibilis, et hoc est verum. Nam in ista propositione 'suppositum potest assumi', hoc subiectum 'suppositum' supponit pro hac natura humana, quia haec natura humana, ex hoc quod non dependet nec innititur alteri, vere est modo suppositum, et ita 'suppositum' vere supponit pro hac natura, sicut 'album' in ista 'album currit' vere supponit pro Sorte, si Sorte sit albus. Sed demonstrando istam naturam humanam, haec est propositio possibilis 'hoc est assumptum a divino supposito', igitur haec est vera 'suppositum potest assumi', sicut haec est vera 'album potest esse nigrum', quia haec est possibilis 'hoc est nigrum, demonstrando aliquid pro quo 'album' supponit; et tamen haec est impossibilis 'album est nigrum'. Yet, notwithstanding this, unless some logical or grammatical mode prevents it, the following propositions are true: 'a suppositum can be assumed by the Word', 'a suppositum can be united to the Word', 'a meritorious act can come about from God alone', because through none of these propositions is anything denoted except that a proposition in which the predicate is predicated of a pronoun indicating that for which the subject supposits is possible, and this is true.

For in the proposition 'a suppositum can be assumed', the subject 'suppositum' supposits for this human nature, because this human nature, from the fact that it neither depends on nor needs the support of another, is now truly a suppositum, and so 'suppositum' truly supposits for this nature, just as the 'white thing' in 'a white thing runs' truly supposits for Socrates, if Socrates is white.

But when that human nature is indicated, then 'this is assumed by a divine suppositum' is a possible proposition, therefore 'a suppositum can be assumed' is true, just as 'a white thing can be black' is true. For 'this is black', indicating something for which 'white thing' supposits, is possible, and yet 'a white thing is black' is impossible.

Similiter omnes tales sunt verae sub eodem sensu 'homo potest assumi', 'causatum ab agente creato potest causari a solo Deo', 'visum a Sorte et Platone potest videri a solo Sorte' et huiusmodi. Et tamen istae sunt impossibiles 'homo est assumptus', causatum ab agente creato causatur a solo Deo', visum a Sorte et Platone videtur a solo Sorte', et sic de aliis. Likewise, all propositions such as the following are true in the same sense: 'a man can be assumed', 'a thing caused by a created agent can be caused by God alone', 'a thing seen by Socrates and Plato can be seen by Socrates alone', and so on. And yet these propositions are impossible: 'a man is assumed', 'A thing caused by a created agent is caused by God alone', 'a thing seen by Socrates and Plato is seen by Socrates alone', and so on.
Secundo sciendum est quod tales propositiones de modo consimiliter se habent ad suas singulares sicut propositiones de inesse, et ideo impossibile est quod talis universalis sit vera vel necessaria vel contingens nisi quaelibet singularis sit vera vel necessaria vel contingens. Second, it should be known that such modal propositions stand to their singulars just as assertoric propositions [stand], and therefore it is impossible that such a universal proposition is true, or necessary, or contingent, unless each of its singulars is true, or necessary, or contingent.
Similiter, sicut propositio de inesse potest esse impossibilis non obstante quod quaelibet singularis sit possibilis, sicut patet de ista 'utrumque istorum est verum', demonstratis duobus contradictoriis contingentibus, sic aliquando -- quamvis raro -- potest universalis de modo esse impossibilis et quaelibet singularis possibilis, sicut patet in ista 'utrumque istorum necessario est verum', demonstratis istis 'Sortes fuit in a', 'Sortes non fuit in a'. Haec universalis est impossibilis, et tamen quaelibet singularis est possibilis, nam haec est possibilis 'haec est necessario vera: Sortes fuit in a', et similiter alia est possibilis. Likewise, just as an assertoric proposition can be impossible, notwithstanding that each of its singulars is possible, as is clear with 'both of these are true', indicating two contradictory contingent propositions, so sometimes, although rarely, a modal universal proposition can be impossible and each of its singulars possible, as is clear in the case of 'both of these are necessarily true', indicating the proposition 'Socrates was in a' and 'Socrates was not in a'. This universal proposition is impossible, and yet each singular is possible, for 'this is necessarily true: "Socrates was in a"' is possible, and likewise the other is possible.
Praedicta autem sunt intelligenda de aliis propositionibus modalibus, sicut de istis 'omnis homo scitur a te esse animal', nam ad veritatem istius requiritur quod quaelibet talis sit vera 'ista est scita a te: iste est animal, et iste est animal', et sic de singulis. Et ideo haec est falsa de virtute sermonis 'omnis homo scitur a te esse animal' et ista similiter 'omnis homo ignoratur a te esse animal'. Et ita de multis aliis. Now the previous points should also be understood to apply to other modal propositions, for example 'every man is known by you to be an animal', for in order for this proposition to be true, it is required that each following proposition is true: 'this is known by you: "This is an animal, and that is an animal"', and so on. And therefore 'every man is known by you to be an animal' is literally false, and likewise 'Every man is not known by you to be an animal'. And so with many others.

Notes

  1. I.e. the type dealt with in the previous chapter: