Authors/Ockham/Summa Logicae/Book II/Chapter 29

Latin	English
[2.29. DE CONVERSIONE PROPOSITIONUM MODALIUM QUAE NON AB OMNIBUS CONCEDUNTUR ESSE MODALES, CUIUSMODI SUNT 'OMNEM HOMINEM CURRERE EST VERUM' ET CONSIMILIA]	Chapter 29. On the Conversion of Modal Propositions which are not Conceded by Everyone to be Modal, such as are "That Every Man Runs is True" and the like.
Dicto de conversione propositionum modalium quae ab omnibus conceduntur esse modales, restat dicere de conversione propositionum modalium quae non ab omnibus conceduntur esse modales, quae tamen vere sunt modales, sicut dictum est prius'. Et quia sunt quasi innumerabiles, ideo non intendo dicere de omnibus in speciali, sed volo dare aliquas regulas generales.	Having discussed the conversion of modal propositions which are conceded by all to be modal, it remains to speak about the conversion of modal propositions which are not conceded by all to be modal, which nevertheless are truly modal, as was said before. And because they are almost innumerable, I do not intend to speak about all of them in detail, but I wish to give some general rules.
Est autem sciendum quod quando est aliquod nomen modale quod potest verificari de uno convertibilium sine hoc quod verificetur de reliquo, talis propositio modalis, sumpta in sensu compositionis, vel etiam aequivalens tali, non convertitur simpliciter, quamvis sua de inesse convertatur simpliciter. Si autem talis modus possit verificari de antecedente sine hoc quod verificetur de consequente, talis propositio, sumpta in sensu compositionis, vel aequivalens ei, non convertitur per accidens nec simpliciter, quamvis sua de inesse convertatur per accidens.	But it should be known that when there is some modal term that can be verified about one of the convertibles without being verified about the rest, such a modal proposition, taken in the sense of composition, or even equivalent to such, is not converted simply, although its proposition of inherence is converted simply. But if such a mode can be verified about the antecedent without being verified about the consequent, such a proposition, taken in the sense of composition, or equivalent to it, is not converted accidentally or simply, although its proposition of inherence is converted accidentally.
Si autem talis modus non possit competere uni convertibilium nisi canveniat reliquo, semper talis propositio in sensu compositionis vel aequivalens ei convertitur simpliciter si sua de inesse convertatur simpliciter; et proportionaliter convertitur sicut sua de inesse. Si autem talis modus non possit competere antecedenti nisi competat consequenti, tunc illa propositio convertitur per accidens sicut sua de inesse.	But if such a mode cannot belong to one of the convertibles unless it belongs to the rest, such a proposition in the sense of composition or its equivalent is always converted simply if its proposition of inherence is converted simply; and it is converted proportionally as its proposition of inherence. But if such a mode cannot belong to the antecedent unless it belongs to the consequent, then that proposition is converted accidentally like its proposition of inherence.
Ex ista regula patet quod ista conversio est bona 'hominem currere est verum, igitur currens esse hominem est verum'; similiter ista 'omnem hominem currere est verum, igitur aliquod currens esse hominem est verum'; nam prima tenet per istam regulam 'si unum convertibilium est verum, reliquum est verum', et secunda per istam 'si antecedens est verum, consequens est verum'; quae ambae sunt verae.	From this rule it is clear that this conversion is good: 'that a man runs is true, therefore that a running thing is a man is true'; similarly this 'that every man runs is true, therefore that some running thing is a man is true'; for the first holds by this rule 'if one of the convertibles is true, the rest is true', and the second by this rule 'if the antecedent is true, the consequent is true'; both of which are true.
Similiter ista conversio est bona 'nullum hominem currere est falsum, igitur nullum currens esse hominem est falsum', quia tenet per istam regulam 'si unum convertibilium est falsum, reliquum est falsum. Sed ista conversio non valet 'omnem hominem currere est falsum, igitur aliquod currens esse hominem est falsum', quia tenet per istam regulam 'si antecedens est falsum, consequens est falsum'; quae falsa est.	Similarly, this conversion is good 'that no man runs is false, therefore that no running thing is a man is false', because it holds by this rule 'if one of the convertibles is false, the rest is false. But this conversion is not valid 'that every man runs is false, therefore that some running thing is a man is false', because it holds by this rule 'if the antecedent is false, the consequent is false'; which is false.
Ex istis patet quod quando universalis affirmativa talis non convertitur per accidens, frequenter particularis affirmativa et similiter particularis negativa convertuntur per accidens, per istam regulam 'consequens est falsum, ergo antecedens'.	From these it is clear that when such a universal affirmative is not converted accidentally, frequently particular affirmatives and similarly particular negatives are converted accidentally, by this rule 'the consequent is false, therefore the antecedent (is false)'.
Per praedicta etiam patet quod tales consequentiae non valent 'nullum hominem currere est scitum, igitur nullum currens esse hominem est scitum', quia ista regula non est generaliter vera 'unum convertibilium est scitum, ergo reliquum est scitum' -- Potest enim unum convertibilium sciri, quamvis aliud non sciatur, immo quamvis de alio non cogitetur. Similiter, tales consequentiae non valent 'omnem hominem esse animal est per se primo modo, ergo aliquod animal esse hominem est per se primo modo', quia non sequitur 'antecedens est per se primo modo, ergo consequens est per se primo modo'; nec valet 'omnem hominem esse risibile est per se secundo modo, ergo aliquod risibile esse hominem est per se secundo modo'. Et ita in talibus semper aspiciendum est ad tales propositiones 'unum convetibilium est tale, igitur reliquum est tale', 'antecedens est tale, igitur consequens est tale', et per istas potest sciri quae propositio in sensu compositionis vel aequivalens ei convertitur sicut sua de inesse et quae non.	From the above it is also clear that such consequences are not valid 'it is known that no man runs, therefore that no running thing is a man is known', because this rule is not generally true 'one of the convertibles is known, therefore the rest is known' -- For one of the convertibles can be known, although the other is not known, indeed although the other is not thought of. Similarly, such consequences are not valid: 'that every man is an animal is per se in the first mode, therefore that some animal is a man is per se in the first mode', because it does not follow 'the antecedent is per se in the first mode, therefore the consequent is per se in the first mode'; nor is it valid 'that every man can laugh is per se in the second mode, therefore that something that can laugh is a man is per se in the second mode'. And so in such cases we must always look to such propositions as 'one of the convertibles is such, therefore the rest is such', 'the antecedent is such, therefore the consequent is such', and by these we can know which proposition in the sense of composition or its equivalent is converted as its proposition of inherence and which is not.
Sed circa conversionem talium propositionum in sensu divisionis et aequivalentium eis est sciendum quod semper vel frequenter convertuntur sicut aliqua propositionum modalium de quibus dictum est prius in speciali. Sicut ista 'album scitur esse homo' non convertitur in istam 'igitur aliquis homo scitur esse albus', nam posito quod sciam Sortem esse hominem, et quod sit albus et tamen hoc ignorem, tunc haec est vera 'aliquod album scitur a me esse homo'; quia iste syllogismus expositorius est bonus 'Sortes scitur a me esse homo; Sortes est albus; igitur aliquod album scitur a me esse homo'. Et tamen haec est falsa 'aliquis homo scitur a me esse albus', ponatur quod nesciam quod aliquis homo est albus, et ideo prima convertitur in istam 'igitur aliquid quod scitur esse homo, est album'. Similiter ista conversio non valet 'Deus trinus et unus scitur a philosophis esse immortalis, igitur aliquod immortale scitur a philosophis esse Deus trinus et unus', sed convertitur in istam 'igitur aliquid quod a philosophis scitur esse immortale, est Deus trinus et unus'.	But regarding the conversion of such propositions in the sense of division and its equivalents, it should be known that they are always or frequently converted like some of the modal propositions that were previously discussed in detail. Just as the statement 'a white thing is known to be a man' is not converted into the statement 'therefore some man is known to be white', for supposing that I know that Socrates is a man, and that he is white, and yet I do not know this, then the statement 'something white is known to be a man' is true; because this expository syllogism is good 'Socrates is known to be a man; Socrates is white; therefore some white thing is known to be a man'. And yet the statement 'some man is known to be white by me' is false, let it be assumed that I do not know that some man is white, and therefore the first statement is converted into the statement 'therefore something that is known to be a man is white'. Similarly, this conversion is not valid 'The triune God is known by philosophers to be immortal, therefore something immortal is known by philosophers to be the triune God', but it is converted into this 'therefore something that is known by philosophers to be immortal is the triune God'.
Et si dicatur quod haec est falsa 'Deus trinus et unus scitur a philosophis esse immortalis', quia impossibile est quod philosophi naturaliter sciant istam 'Deus trinus et unus est immortalis', igitur haec non est vera 'Deus trinus et unus scitur a philosophis esse immortalis':	And if it is said that this is false, 'The triune and one God is known by philosophers to be immortal', because it is impossible for philosophers to naturally know this: 'The triune and one God is immortal', then this is not true: 'The triune and one God is known by philosophers to be immortal':
Dicendum quod ista est vera 'Deus trinus et unus scitur a philosophis esse immortalis', et tamen ipsi nesciunt istam, immo negarent eam et dicerent eam esse falsam, quia dicerent quod implicat falsum, scilicet Deum esse trinum et unum. Et tamen ipsa est vera, quia per istam non plus denotatur nisi quod de illo qui est trinus et unus, quamvis nesciatur ipsum esse trinum et unum, scitur a philosophis quod est immortalis. Unde per istam 'Deus trinus et unus scitur a philosophis esse immortalis' non denotatur nisi ista copulativa 'Deus est trinus et unus et de illo scitur a philosophis quod est immortalis'. Et hoc est verum, quia utraque pars istius copulativae est vera.	It must be said that this is true, 'God, triune and one, is known by philosophers to be immortal', and yet they themselves do not know this, indeed they would deny it and say that it is false, because they would say what implies a falsehood, namely that God is triune and one. And yet it is true, because by this nothing more is denoted than that of Him who is triune and one, although it is not known that He is triune and one, it is known by philosophers that He is immortal. Hence by this 'God, triune and one, is known by philosophers to be immortal' nothing is denoted except this conjunction 'God is triune and one, and of Him it is known by philosophers that He is immortal'. And this is true, because both parts of this conjunction are true.
Similiter, quod haec sit vera, patet, nam ista est vera 'aliquid quod scitur a philosophis esse immortale, est Deus trinus et unus', quia Deus, qui scitur a philosophis esse immartalis, est Deus trinus et unus. Tunc arguo per syllogismum expositorium 'Deus est Deus trinus et unus; Deus est aliquid quod scitur a philosophis esse immortale; ergo aliquid quod scitur a philosophis esse immortale, est Deus trinus et unus'. Praemissae sunt verae, ergo conclusio. Et ultra, similiter sequitur 'Deus scitur a philosophis esse immortalis; Deus est trinus et unus; igitur Deus trinus et unus scitur a philosophis esse immortalis'. Sic igitur patet evidenter veritas propositionis acceptae et bonitas conversionis.	Similarly, it is clear that this is true, for it is true that 'something that is known by philosophers to be immortal is God triune and one', because God, who is known by philosophers to be immortal, is God triune and one. Then I argue by an expository syllogism 'God is God triune and one; God is something that is known by philosophers to be immortal; therefore, something that is known by philosophers to be immortal is God triune and one'. The premises are true, therefore the conclusion. And further, similarly it follows 'God is known by philosophers to be immortal; God is triune and one; therefore, God triune and one is known by philosophers to be immortal'. Thus, therefore, the truth of the accepted proposition and the goodness of the conversion are clearly evident.
Similiter ista 'intellectus cognoscitur esse anima intellectiva' non convertitur in istam 'igitur anima intellectiva cognoscitur esse intellectus'; sed in istam 'igitur aliquid quod cognoscitur esse anima intellectiva, est intellectus'.	Similarly this, 'the intellect is known to be an intellectual soul' is not converted into 'therefore the intellectual soul is known to be an intellect', but into 'therefore something that is known to be an intellectual soul is an intellect'.
Similiter ista 'aliquis veniens cognoscitur a te esse Coriscus' non convertitur in istam 'ergo Coriscus cognoscitur a te esse veniens', sed in istam 'aliquis, qui cognoscitur a te esse Coriscus, est veniens'.	Similarly, the sentence 'someone coming is known by you to be Coriscus' is not converted into the sentence 'therefore Coriscus is known by you to be coming', but into the sentence 'someone, who is known by you to be Coriscus, is coming'.
Similiter ista 'aliquis homo per se est animal' non convertitur in istam 'aliquod animal per se est homo', sed in istam 'aliquid, quod per se est animal, est homo'. Similiter ista 'album per se aedificat' convertitur in istam 'aliquid, quod per se aedificat, est album'.	Similarly, 'some man is per se an animal' is not converted into 'some animal is per se a man', but into 'something that is per se an animal is a man'. Similarly, 'a white thing builds per se' is converted into 'something that builds per se is white'.
Similiter ista 'Deus per accidens est creans' non convertitur in istam 'aliquid creans per accidens est Deus', sed in istam 'aliquid, quod per accidens creat, est Deus'.	Similarly, the statement 'God is creating by accident' is not converted into the statement 'something accidentally creating is God', but into the statement 'something, which accidentally creates, is God'.
Et sicut dictum est de istis, ita dicendum est de aliis, quod talis propositio convertitur vel sicut propositio de necessario vel de possibili vel de impossibili vel de contingenti.	And as was said about these, so it must be said about the others, that such a proposition is converted either as a proposition of necessity or of possibility or of impossibility or of contingency.
Et forte ista fuit causa quare Philosophus specialem tractatum de talibus propositionibus et proprietatibus earum et conversionibus non fecit, quia ex illis quae scienda sunt circa propositiones de necessario, de cantingenti, de possibili et impossibili et quibusdam paucis, potest faciliter sciri quid sentiendum sit de aliis modalibus et proprietatibus earum. Quarum tamen ignorantia, sicut ignorantia propositionum et proprietatum earum, facit multos modernos errare et intricari in theologia et in aliis scientiis particularibus, tam speculativis quam practicis.	And perhaps this was the reason why the Philosopher did not make a special treatise on such propositions and their properties and conversions, because from what is to be known about propositions of necessity, possibility, impossibility, and some few others, it can easily be known what is to be thought of other modals and their properties. However, ignorance of these, like ignorance of propositions and their properties, causes many moderns to err and become entangled in theology and other particular sciences, both speculative and practical.
Ad evidentiam autem conversionum omnium modalium propositionum sciendum est quod communiter propositiones modales in sensu divisionis et eis aequivalentes similiter convertuntur sicut illae de inesse in quibus aliqua adverbialis determinatio additur verbo. Nam sicut in illis adverbialis determinatio et ei aequivalens non est addenda eodem modo compositioni in convertente et conversa, sed in convertente debet poni praecise a parte subiecti, sicut dictum est, ita modus in consequente debet poni totaliter a parte subiecti, sicut exemplificatum est.	To make clear the conversions of all modal propositions, it should be known that modal propositions in the sense of division and their equivalents are commonly converted in the same way as those of inherence in which some adverbial determination is added to the verb. For just as in them the adverbial determination and its equivalent are not to be added in the same way to the composition in the converting and converted, but in the converting it must be placed precisely on the part of the subject, as has been said, so the mode in the consequent must be placed entirely on the part of the subject, as has been exemplified.