Authors/Thomas Aquinas/posteriorum/L2/Lect5

Lecture 5 Whether a quod quid can be demonstrated by taking that which is required for a quod quid

Latin	English
	Lecture 5 (92a6-b3) WHETHER A QUOD QUID CAN BE DEMONSTRATED BY TAKING THAT WHICH IS REQUIRED FOR A QUOD QUID
lib. 2 l. 5 n. 1 Postquam philosophus ostendit quod non potest demonstrari quod quid est, nec per convertibiles terminos, nec per viam divisionis, hic ostendit ulterius quod non potest quod quid est demonstrari, accipiendo id quod requiritur ad quod quid est. Et circa hoc duo facit: primo, ostendit propositum; secundo, concludit ex omnibus praemissis quod nullo modo quod quid est demonstrari possit; ibi: qualiter igitur definiens et cetera. Circa primum duo facit: primo, inducit rationes proprias ad propositum; secundo, inducit quamdam rationem communem ad id quod nunc dicitur, et ad id quod supra dictum est; ibi: ad utrosque autem et cetera. Circa primum duo facit: primo, ostendit quod non potest demonstrari quod quid est per hoc quod accipiatur id quod pertinet ad rationem eius quod quid est; secundo, ostendit quod non potest demonstrari quod quid est huius rei, ex hoc quod accipitur quod quid est alterius rei; ibi: ex suppositione autem et cetera. Circa primum duo facit: primo, movet quaestionem; secundo, argumentatur ad propositum; ibi: aut iterum accipit et cetera.	After showing that the quod quid cannot be demonstrated either by convertible terms or by the method of division, the Philosopher here shows that it cannot be demonstrated by taking that which is required for a quod quid. In regard to this he does two things. First, he shows what he proposes. Secondly, he concludes from all of the foregoing that there is no way in which quod quid maybe demonstrated (92a34). Concerning the first he does two things. First, he employs reasons proper to what he proposes. Secondly, he employs a reason common to what is now being said and to what was said above (92a28). Concerning the first he does two things. First, he shows that the quod quid cannot be demonstrated by taking that which pertains to the notion of its quod quid. Secondly, he shows that the quod quid of this thing cannot be demonstrated by taking the quod quid of some other thing (9240). In regard to the first he does two things. First, he raises the question. Secondly, he argues for his proposal (92a9).
lib. 2 l. 5 n. 2 Quaerit ergo primo, utrum contingat demonstrare quid sit aliquid secundum suam substantiam, ex tali suppositione, per quam accipiatur quod quid erat esse alicuius rei, ex illis conditionibus quae sunt propriae ei quod quid est. Puta si aliquis probet quod animal gressibile bipes sit quod quid est hominis, accipiens pro medio quod haec ratio convertitur cum homine, et constat ex genere et differentia. Haec autem sola requiruntur ad hoc quod quid est, et totum hoc quod dictum est, est proprium ei quod quid est, quia est esse illi, scilicet ei quod est quod quid est: quasi dicat quod hoc quod est esse rationem convertibilem, ex genere et differentiis constantem, est omnino idem ei quod quid est.	He asks therefore first (92a6) whether one might demonstrate what something is according to its substance by supposing that the quod quid of a thing can be obtained if one satisfies the conditions which are proper to the quod quid: for example, if one were to prove that two-footed land animal is the quod quid of man, having taken as middle the fact that this notion is converted with man and is composed of genus and difference; which are the only conditions required for a quod quid. Furthermore, this whole, which has been stated, is proper to the quod quid because it is the being or reality of it, i.e., of that which is quod quid. It is as though he were saying that being a convertible notion composed of a genus and difference is exactly the same as being the quod quid.
lib. 2 l. 5 n. 3 Deinde cum dicit: an iterum accepit etc., obiicit ad praedictam quaestionem duabus rationibus, ostendens quod non potest quod quid est praedicto modo demonstrari. Quarum prima est, quia sicut praemissi modi demonstrandi deficiunt in hoc quod accipiunt id quod quaeritur, ita est in proposito. Accipitur enim et in hoc modo probationis quod quid erat esse; puta dum accipitur quod omnis ratio convertibilis, constans ex genere et differentiis, significat quod quid est: et ita inconveniens est probatio. Necesse est enim id ad quod demonstratio inducitur, non supponere quasi medium; sed potius per aliud medium demonstrare.	Then (92a9) he lodges two objections against the above question, showing that the quod quid cannot be demonstrated in the way it suggests. The first of these is that just as the previously mentioned ways of demonstrating failed because they assumed the very thing in question, so too in the present instance. For it, too, assumes the quod quid erat esse, as for example when it is assumed that every convertible notion composed of genus and difference signifies the quod quid est; consequently, the proof is not acceptable. For one must never take as middle the very thing the demonstration is intended to prove; rather it is necessary to demonstrate it through some other middle.
lib. 2 l. 5 n. 4 Secundam rationem ponit ibi: amplius sicut neque in syllogismo etc.; quae sumitur ex similitudine syllogismi. Cum enim aliquis syllogizat, non oportet quod accipiat definitionem syllogismi ad syllogizandum; quia ea ex quibus procedit syllogismus, hoc modo se habent, quod semper quodlibet eorum est aut tota propositio, idest universalis seu maior, aut est pars, idest particularis seu minor, quae sumitur sub maiori. Et ita definitio syllogismi non est aliquid eorum ex quibus procedit syllogismus. Et similiter si aliquis velit syllogizare quod quid erat esse alicuius rei, non oportet quod accipiat quid sit quod quid erat esse: sed oportet hoc seorsum haberi in mente, praeter ea quae ponuntur in definitione vel syllogismo. Huiusmodi enim rationes syllogismi et definitionis se habent in definiendo et syllogizando, sicut regulae artis, ad quas debet aspicere artifex in operando. Artifex autem qui facit cultellum, non facit operando regulam, secundum quam operatur: sed secundum regulam, quam habet in mente, examinat an cultellus bene sit factus. Ita etiam ille qui syllogizat non accipit rationem syllogismi in syllogizando: sed per rationem syllogismi examinat syllogismum factum an sit bonus.	Then (92a11) he gives the second reason, which is based on a likeness to a syllogism. For when a person syllogizes, he is not required to use the definition of syllogism in order to syllogize; because the items from which a syllogism proceeds are such that each item is either a whole proposition, i.e., a universal or major proposition, or a part, i.e., a particular or minor proposition subsumed under the major one. Consequently, the definition of a syllogism is not one of the things from which a syllogism proceeds. In like manner if someone wishes to syllogize the quod quid erat esse of something, he is not required to mention what a quod quid erat esse is; but he must have this in reserve in his mind over and above the items which are put in the definition or in the syllogism. For these notions of a syllogism and of a definition function in defining and syllogizing as rules of art which an artisan must respect in his works. Now an artisan who makes a knife does not do so by establishing the rules according to which he works, but in the light of the rules he has in his mind he examines whether the knife was made well. So, too, a person who syllogizes does not mention the notion of a syllogism as he syllogizes, but in view of the notion of a syllogism he examines the syllogism he made, in order to see whether it is good.
Unde si aliquis dubitet, syllogismo facto, an sit syllogizatum vel non, poterit syllogizans obviare, ostendendo quod sit syllogizatum, ostendendo quod syllogismus sit tale aliquid. Similiter etiam ei qui intendit syllogizare quod quid erat esse, convenit ut habeat seorsum in mente rationem eius quod quid erat esse: ut si aliquis dicat quod non est syllogizatum quod quid erat esse, ipse dicat quod immo, quia tale aliquid ponitur quod quid erat esse. Sic ergo patet quod syllogizans quod quid erat esse, neque debet sumere quid est syllogismus, neque quid est quod quid erat esse.	Hence if a person should wonder, once a syllogism has been formed, whether it syllogized or not, the one who formed the syllogism can settle this doubt by showing that it does syllogize, on the ground that a syllogism is such and such a thing. So, too, a person who intends to syllogize the quod quid erat esse should have reserved in his mind the notion of what a quod quid erat esse is, so that if someone should say that a quod quid erat esse has not been syllogized, he can answer that it has, because such and such is put down as the quod quid erat esse. Thus, therefore, it is clear that a person who syllogizes a quod quid erat esse should not state what a syllogism is or what a quod quid erat esse is.
lib. 2 l. 5 n. 5 Deinde cum dicit: et si ex suppositione etc., ostendit quod non potest demonstrari quod quid est unius rei ex quod quid est alterius rei. Et circa hoc duo facit: primo, proponit quod intendit; secundo, probat propositum; ibi: etenim hic accipiens et cetera. Dicit ergo primo quod etiam non probatur quod quid est, si aliquis velit hoc probare ex suppositione quod quid est alterius rei. Puta si aliquis sic procedat accipiens quod idem sit esse divisibili et malo, idest quod divisio sit quod quid est mali, et ulterius argumentetur sic: in omnibus quae habent contrarium, contrarii est contrarium quod quid est; sed bono est contrarium malum, et indivisibile est contrarium divisibili; sequitur ergo quod indivisibile sit quod quid est ipsius boni. Et sumuntur ista exempla secundum opinionem Platonis, qui posuit quod eadem est ratio unius et boni. Videmus enim quod unumquodque appetit unitatem sicut proprium bonum. Unum autem est idem quod indivisibile; et sic per oppositum sequitur quod malum sit idem quod divisibile. Unumquodque enim refugit divisionem sui, quia per hoc tendit ad diminutum et imperfectum.	The (92a20) he shows that the quod quid of one thing cannot be demonstrated from the quod quid of another thing. Concerning this he does two things. First, he proposes what he intends. Secondly, he proves what he proposes (92a23). He says therefore first (92a20) that the quod quid is not proved, if someone wished to prove it by supposing the quod quid of some other thin ; for example, if someone were to proceed in such a way as to assume that the being or reality of divisible and of evil is the same, i.e., that division is the quod quid of evil, and then argued in the following manner: “In all things which have a contrary the quod quid of one contrary is a contrary; but the contrary of good is evil, and of divisible the contrary is indivisible: therefore, it follows that indivisible is the quod quid of the good.” And these examples are taken according to Plato’s opinion that the notion of the one and of the good are the same. For we notice that everything seeks unity as its own good. But one is the same as indivisible; and so in virtue of the opposition it follows that evil is the same as divisible. For everything shuns division of the self, because through division it tends to what is shattered and imperfect.
lib. 2 l. 5 n. 6 Deinde cum dicit: etenim hic accipiens etc., probat propositum, scilicet quod non possit demonstrari quod quid est; et hoc duabus rationibus. Quarum prima est, quia etiam in hoc modo probationis demonstrat aliquis accipiendo quod quid erat esse, et ita accipit quod oportet probare.	Then (92a23) he proves what he has proposed, namely, that the quod quid cannot be demonstrated: and this by giving two reasons. The first of these is that even according to this method one demonstrates by assuming the quod quid erat esse, and thus he assumes what he should have proved.
lib. 2 l. 5 n. 7 Secundam rationem ponit ibi: accipit autem ad demonstrandum etc.; et dicit quod non solum est inconveniens quod accipiatur quod quid erat esse ad demonstrandum, sed et alterum inconveniens fit quod accipitur quod quid erat esse ad demonstrandum quod quid erat esse: quia etiam in demonstrationibus in quibus probatur hoc de hoc, puta passio de subiecto, accipitur pro medio quod quid erat esse, non tamen quod quid erat esse quod accipitur, est ipsummet quod debet concludi, vel aliquid quod habeat eamdem rationem et convertatur. Eamdem autem rationem habet quod bonum sit indivisibile, et malum divisibile; et haec duo convertuntur, quia posito uno ponitur alterum, et e converso.	Then (92a24) he gives the second reason, saying that not only is it improper to take the quod quid erat esse when demonstrating, but this impropriety is compounded when one takes a quod quid erat esse to demonstrate a quod quid erat esse: because even in demonstrations in which this is proved of this, say a proper attribute of a subject, a quod quid erat esse is taken as middle; nevertheless the one so taken is not the very thing which was to be concluded or something which has the same notion and is converted. But good and indivisible, and evil and divisible, have the same notion; and each pair is converted, because one being posited, the other is posited, and vice versa.
lib. 2 l. 5 n. 8 Deinde cum dicit: ad utrosque autem et secundum divisionem etc., inducit rationem communem contra eum qui demonstrat ex suppositione et divisione; et dicit quod eadem oppositio habet locum contra utrosque, scilicet contra eum qui vult demonstrare quod quid est per divisionem, et contra eum qui utitur suppositione quod quid est in syllogismo. Manifestum est enim quod definitio significat unum aliquid: unde ea quae ponuntur in definitione, ad significandum unitatem, debent poni absque copula; puta ut dicatur quod homo est animal gressibile bipes, non autem debet dici quod homo sit animal et bipes. Unde si aliquis vult probare quod quid est, oportet quod probet ex his, quae assumuntur, fieri unum. Sed non est necessarium, secundum praedictas vias divisionis et suppositionis, quod ex his quae accipiuntur ad definiendum, fiat unum praedicatum: sed poterit esse quod sint multa, puta si dicatur quod homo est grammaticus et musicus. Videtur igitur quod secundum vias praedictas, non probetur quod quid est.	Then (92a28) he presents a common reason against anyone who demonstrates from supposition and division. And he says that the same opposition is directed against both, namely, against one who tries to demonstrate the quod quid by division and against one who proceeds by laying down the quod quid in the syllogism. For clearly a definition signifies something which is one: hence to signify this oneness the items laid down in the definition should be arranged without a conjunction; thus one should say that man is a two-footed land animal, but not that man is an animal and two-footed. Hence if anyone desires to prove the quod quid, he must prove that one thing is formed from the things assumed. But it is not required, according to the above-cited methods of division and supposition, that one predicate be formed from these items which are taken for defining: since there might be several, for example, if one should state that man is grammatical and musical. It seems therefore that according to the ways mentioned above, the quod quid is not proved.
lib. 2 l. 5 n. 9 Deinde cum dicit: qualiter igitur definiens etc., concludit ex praemissis quod nullo modo potest probari quod quid est; et dicit: si igitur neque per terminos convertibiles, neque per divisionem, neque per suppositionem demonstratur quod quid est, quomodo igitur definiens poterit demonstrare substantiam rei vel quod quid est? Iam enim ex praemissis patet quod non probat, sicut manifestum faciens ex his quae sunt per se nota, quod necesse sit alterum aliquid sequi per ea quae dicta sunt, quod requiritur ad demonstrationem.	Then (92a34) he concludes from the foregoing that there is no way to prove the quod quid, saying: if then the quod quid cannot be proved either by convertible terms or division or opposition, how will the definer be able to demonstrate the substance of a thing or the quod quid? For it is now clear from the foregoing that he does not prove it according to the method whereby, in virtue of items that are per se known, one manifests that something else must follow through things which are said-which is required for a demonstration.
Relinquitur autem praeter tres modos quartus modus, qui est per inductionem. Sed nec contingit probare quod quid est per singularia manifesta, ita scilicet quod aliquid praedicetur de omnibus, et non sit aliquid eorum quod aliter se habeat: quia sic inducendo non demonstrabit quod quid est, sed demonstrabit aliquid esse vel non esse, puta quod omnis homo est animal, vel nullus homo est lapis.	However, besides these three modes there is a fourth, namely, through induction. But it turns out that the quod quid cannot be proved by manifest singulars, namely, in such a way that something is predicated of all and is not anything that might be otherwise: because one who thus proceeds by induction will not demonstrate the quod quid but will demonstrate that something is or is not; for example, that every man is an animal, or that no animal is a stone.
Nullus autem alius modus relinquitur ad demonstrandum quod quid est: nisi forte modus demonstrationis qui est ad sensum, sicut cum aliquid demonstratur digito. Manifestum est autem quod hic modus non potest competere in proposito: quia quod quid est non est obiectum sensus, sed intellectus, ut dicitur in III de anima. Relinquitur ergo quod nullo modo possit demonstrari quod quid est.	But no other method is available for demonstrating the quod quid, save perhaps the method of demonstrating something to the senses, as when something is pointed out with the finger. But it is obvious that this method cannot be invoked in the present instance, because the quod quid is not an object of sense but of intellect, as it is stated in On the Soul III. It remains, therefore, that there is no way in which the quod quid can be demonstrated.