Authors/Thomas Aquinas/posteriorum/L1/Lect19

Lecture 19 How common principles differ from one another

Latin	English
	Lecture 19 (76b23-77a9) HOW COMMON PRINCIPLES DIFFER FROM ONE ANOTHER
lib. 1 l. 19 n. 1 Postquam divisit Aristoteles principia communia a propriis, hic distinguit communia principia ad invicem. Et dividitur in partes tres: in prima, ponit distinctionem communium principiorum ad invicem; in secunda, ostendit differentiam definitionis a quodam genere principiorum communium, ibi: termini igitur non etc.; in tertia, excludit quemdam errorem, ibi: species quidem igitur et cetera. Circa primum duo facit: primo, distinguit communes animi conceptiones a petitionibus, sive suppositionibus; secundo, petitiones et suppositiones ad invicem, ibi: quaecunque quidem igitur et cetera.	After dividing common principles from proper principles, Aristotle now distinguishes among the common principles. His treatment f Is into three parts. In the first he lays down a distinction among the common principles. In the second he shows the difference between a definition and a certain genus of common principles (76b35). In the third he excludes an error (77a5). Concerning the first he does two things. First, he distinguishes the common conceptions in the mind from postulates or suppositions. Secondly, he distinguishes among the latter (76b27).
lib. 1 l. 19 n. 2 Circa primum considerandum est quod communes animi conceptiones habent aliquid commune cum aliis principiis demonstrationis, et aliquid proprium. Commune quidem habent, quia necesse est tam ista, quam alia principia per se esse vera. Proprium autem est horum principiorum quod non solum necesse est ea per se vera esse, sed etiam necesse est videri quod per se sint vera. Nullus enim potest opinari contraria eorum.	With respect to the first (76b23) it should be noted that the common. conceptions in the mind have something in common with the other principles of demonstration and something proper: something common, because both they and the others must be true in virtue of themselves. But what is proper to the former is that it is necessary not only that they be true of themselves but that they be seen to be such. For no one can think their contraries. He says, therefore, that that principle of which it is not only required that it be in virtue of itself but further required that it be seen, namely, a common conception in the mind or a dignity, is neither a postulate nor a supposition.
lib. 1 l. 19 n. 3 Dicit ergo quod illud principium, quod necesse est non solum per seipsum esse, sed etiam ulterius necesse est, ipsum videri, scilicet communis animi conceptio vel dignitas, non est neque petitio neque suppositio. Quod sic probat. Petitio et suppositio exteriori ratione confirmari possunt, idest argumentatione aliqua. Sed communis animi conceptio non est ad exterius rationem, quia non potest probari per aliquam argumentationem, sed est ad eam, quae est in anima, quia lumine naturalis rationis statim fit nota. Et quod non sit ad exterius rationem patet, quia non fit syllogismus ad probandas huiusmodi communes animi conceptiones. Et quod huiusmodi non sunt notae per exteriorem rationem, sed per interiorem, probat per hoc, quod exteriori rationi potest instari vel vere vel apparenter: interiori autem rationi non est possibile semper instari. Et hoc ideo, quia nihil est adeo verum, quin voce possit negari. Nam et hoc principium notissimum, quod non contingat idem esse et non esse, quidam ore negaverunt. Quaedam autem adeo vera sunt, quod eorum opposita intellectu capi non possunt; et ideo interiori ratione eis obviari non potest, sed solum exteriori, quae est per vocem. Et huiusmodi sunt communes animi conceptiones.	He proves this in the following way: A postulate and a supposition can be confirmed by a reason from without, i.e., by some argumentation; but a common conception in the mind does not bear on a reason from without (because it cannot be proved by any argument), but bears on that reason which is in the soul, because it is made known at once by the natural light of reason. That it does not bear on any reason from without is shown by the fact that a syllogism is not formed to prove such common conceptions of the mind. Furthermore, that these are not made known by an outward reason but by the inward he proves by the fact that it is possible to contest an outward reason, either truly or apparently, but it is not always possible to do so with the inward reason. This is so because nothing is so true that it cannot be denied orally. (For even this most evident principle that the same thing cannot be and not be has been orally denied by some). On the other hand, some things are so true that their opposites cannot be conceived by the intellect. Therefore, they cannot be challenged in the inward reason but only by an outward reason which is by the voice. Such are the common conceptions in the mind.
lib. 1 l. 19 n. 4 Deinde, cum dicit: quaecunque igitur etc., distinguit suppositiones et petitiones ad invicem. Sciendum tamen est, quod aliquid commune habent, et in aliquo differunt. Hoc quidem commune est eis, quod cum sint demonstrabilia, tamen demonstrator accipit ea non demonstrans, et praecipue, quia non sunt demonstrabilia per suam scientiam, sed per aliam, ut supra dictum est. Unde et inter immediata principia computantur, quia demonstrator utitur eis absque medio, eo quod non habeant medium in illa scientia.	Then (76b27) he distinguishes suppositions and postulates from one another. Here, too, it should be noted that they have something in common and something in which they differ. What is common to them is that although they can be demonstrated, the demonstrator assumes them without demonstrating, chiefly because they are not demonstrable by his own science but by another, as explained above. Hence they are reckoned among the immediate principles because the demonstrator uses them without a middle, since they do not have a middle in that science.
Differunt autem ad invicem: quia si quidem talis propositio sit probabilis addiscenti, cui fit demonstratio, dicitur suppositio. Et sic suppositio dicitur non simpliciter, sed ad aliquem. Si vero ille nec sit eiusdem opinionis, neque contrariae, oportet quod demonstrator hoc ab eo petat, et tunc dicitur petitio. Si autem sit contrariae opinionis, tunc erit quaestio, de qua oportet disputari inter eos. Hoc tamen omnibus commune est, quod unoquoque eorum utitur demonstrator non demonstrans, cum sit demonstrabile.	Yet they do differ, because if such a proposition is accepted as reasonable by the pupil to whom a demonstration is being made, it is called a “Supposition.” In that case it is not called a supposition absolutely, but relative to him. But if the pupil has no reason for or against the proposition, the demonstrator must request him to admit it as reasonable, and then it is called a “postulate.” However, if the pupil has a contrary opinion, then it will be a “question,” which must be settled between them. At any rate, what is common to all of them is that the demonstrator uses each of thein without demonstrating, although they are demonstrable.
lib. 1 l. 19 n. 5 Deinde, cum dicit: termini igitur non sunt etc., distinguit definitiones a suppositionibus per duas rationes; quarum secunda incipit ibi: amplius petitio et cetera. Circa primum duo facit: primo, ponit rationem, quae talis est: omnis petitio, vel suppositio dicit aliquid esse vel non esse; termini autem, idest definitiones, non dicunt aliquid esse vel non esse; termini ergo non sunt suppositiones neque petitiones, per se sumpti. Sed in propositionibus assumpti sunt suppositiones; ut cum dicitur, homo est animal rationale mortale. Sed terminos per se sumptos, oportet solum intelligere; intelligere autem non est supponere, sicut nec audire. Sed illa supponuntur quorumcunque existentium, idest ex quibuscumque existentibus fit conclusio, in eo quod illa sunt, idest propter praemissa.	Then (76b35) he distinguishes definitions from suppositions with two reasons, the second of which begins at (77a3). In regard to the first he does two things. First, he presents this reason: Every postulate or supposition declares something to be or not to be; but terms, i.e., definitions, do not declare that something is or is not. Terms, therefore, taken by themselves, are neither postulates nor suppositions. But when they are employed in propositions they are suppositions, as in the statement, “Man is a rational mortal animal.” But terms taken by themselves are only understood; and understanding is not supposing, any more than hearing is. Rather supposition bears on things that exist such that a conclusion is made from them in regard to what they are, i.e., in virtue of the premises.
lib. 1 l. 19 n. 6 Secundo, ibi: neque geometra etc., excludit quamdam dubitationem. Dicebant enim quidam quod geometra falsa suppositione utebatur, cum diceret lineam esse unius pedis, quae non est unius pedis; aut lineam descriptam in pulvere esse rectam, quae non est recta. Sed ipse dicit quod geometra non supponit falsum propter hoc. Cum enim geometra nihil demonstret de particularibus, sed de universalibus, ut supra dictum est; hae autem lineae sunt quaedam particularia; manifestum est quod de his lineis nihil demonstrat, neque etiam ex eis, sed utitur eis ut exemplis universalium, quae per haec exempla intelliguntur, de quibus et ex quibus demonstrat.	Secondly (76b39), he excludes a doubt. For there were some who said that a geometer uses a false supposition when he says that a line not one foot long is one foot long, or that a line traced in the sand is straight when it really is not. But he says that a geometer does not on this account suppose something false. For since the geometer demonstrates nothing of singulars but of universals, as explained above, and these lines are singulars, it is obvious that he is not demonstrating anything about these lines or from these lines; rather he is using them as examples of the universals (which are understood by examples) from which and about which he demonstrates.
lib. 1 l. 19 n. 7 Deinde, cum dicit: amplius petitio etc., ponit secundam rationem, quae talis est: omnis suppositio vel petitio est in toto vel in parte, idest est propositio universalis vel particularis; sed definitiones neutrum horum sunt, quia in eis nihil ponitur sive praedicatur, neque universaliter, neque particulariter; ergo et cetera.	Then (77a3) he presents the second reason which is this: Every supposition or postulate is in whole or in part, i.e., is either a universal proposition or a particular. But definitions are neither of these, because nothing is placed or predicated in them universally or particularly. Therefore...
lib. 1 l. 19 n. 8 Deinde, cum dicit: species quidem esse etc., ostendit ex praemissis quod non est necessarium ponere ideas, ut Plato posuit. Ostensum est enim supra quod demonstrationes de universalibus sunt, et hoc modo sunt de sempiternis. Non igitur necesse est ad hoc quod demonstratio sit, species esse, idest ideas, aut quodcunque unum extra multa, sicut ponebant Platonici mathematica separata cum ideis, ut sic demonstrationes possint esse de sempiternis. Sed necessarium est esse unum in multis et de multis, si demonstratio debet esse, quia non erit universale, nisi sit unum de multis; et si non sit universale, non erit medium demonstrationis; ergo nec demonstratio.	Then (77a5) he shows from the foregoing that it is not necessary to posit “Ideas,” as Plato did. For it was shown above that demonstrations are concerned with universals and in that sense with eternal things. Therefore, it is not necessary for the validity of demonstration that there be “Forms,” i.e., “Ideas,” or a “one outside the many,” as Plato posited separated mathematical beings along with Ideas in order that thereby demonstrations might bear on eternal things. What is required is that there be “one in many and about many,” if there is to be demonstration, because it will not be universal unless it is “one about many.” And if it is not universal, there will not be a middle of demonstration and, consequently, no demonstration.
Et quod oporteat medium demonstrationis esse universale, patet per hoc quod oportet medium demonstrationis esse unum et idem de pluribus praedicatum non aequivoce, sed secundum rationem eamdem: quod est ratio universalis. Si autem aequivocum esset, posset accidere vitium in arguendo.	That the middle of a demonstration must be universal is plain from the fact that the middle of a demonstration must be some one same thing predicated of many not equivocally but according to the same aspect, which is a universal aspect. But if it should happen to be equivocal, a defect in reasoning would occur.