Volume 2 · pp. 483–486
Book VII, Tractate II. On definition.
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TRACTATUS II. DE DIFFINITIONE.
CAPUT I. Qualiter construitur problema de diffinitione in communi, et primo per locum ab oppositis.
Si autem construere volumus problema de diffinitione, tunc primum quidem scire oportet, quod nullus vel pauci diffinitionem syllogizant, ita quod concludant diffinitionem: solus enim demonstrator quamdam diffinitionem syllogizat, sicut in Posterioribus est ostensum: quae diffinitio dicit quid et non propter quid. Dialecticus autem non syllogizat diffinitionem, quod diffinitio sit: sed de praedicato syllogizat aliquando ex probabilibus et quasi conjecturis, quod insit ut diffinitio. Sed disputantes tale principium quod est diffinitio, accipiunt et supponunt, et interimitur ab ipsis ut qui circa geometriam et numeros considerant: praemittunt enim diffinitiones sicut et principium supponentes: et similiter fit circa alias disciplinabiles scientias quando propter utilitatem.
Qualiter fiat diffinitio alterius et altioris negotii est assignare: hoc enim fit in VII primae philosophiae, ubi determinatur et quid vere diffinitio et quomodo per quidditatem et principia ipsius esse substantialis oportet diffinire. Nunc autem quantum sufficit ad praesentem utilitatem, solum dicendum est, quoniam possibile est fieri diffinitionem, et quod hanc contingit concludi de diffinito et de subjecto: et hoc est ejus quod est syllogismum esse qui diffinitionem ut praedicatum concludi ostendat: et hoc per rationem diffinitionis probatur, nam diffinitio oratio est quae quid est esse rei significat: et ideo oportet ea quae per diffinitionem sive ut diffinitio praedicantur, in eo quod quid est de re diffinita sola praedicari: quia nisi de sola re diffinita praedicarentur, non esset convertibilis diffinitio cum diffinito. Adhuc autem sciendum, quoniam de re in eo quod quid est genera et differentiae praedicantur: genus quidem, quia dicit quid: differentia autem quale, quia dicit quale quod ut forma facit quid esse quod in specie, et ideo specie est quale quid.
Dico igitur quod syllogismo dialectico concluditur praedicatum inesse ut diffinitio: quoniam si quis disputantium sumat ea, genus et differentiam, quae tantum de re specie et subjecto in eo quod quid est praedicantur, talis oratio ex genere et differentia complexa, ex necessitate diffinitio erit, per locum a diffinitione: non enim contingit aliud esse diffinitionem quam rem diffinitam ex genere et differentia: eo quod nihil aliud a genere et differentia in eo quod quid est de re praedicatur. Si ergo contingit syllogizari, quod talis oratio quae est ex genere et differentia concluditur de subjecto, probatum est quod diffinitio concluditur de subjecto. Manifestum est ergo, quod contingit ex diffinitione (hoc est, ad diffinitionem) syllogismum fieri. Ex quibus autem oportet construere et constituere diffinitionem, determinatum est in aliis subtilius, et in VII philosophiae primae et in secundo Posteriorum. Ad propositam autem methodum iidem loci qui ad alia praedicata inducti sunt: quia omnia alia praedicata elementabilia sunt ad praedicatum diffinitionis, et utilia sunt ad construendum, quod aliquid insit ut diffinitio.
Considerandum ergo primo in locis extrinsecis communibus, in quibus magis efficax est locus ab oppositis. Perspiciendum ergo in contrariis et in aliis generibus oppositorum. Perspiciendum, dico, consideranti totas rationes oppositorum, et etiam particulariter secundum unumquodque. Nam si opposita ratio sive diffinitio est oppositi alicujus, tunc necesse est, quia ea quae dicta et assignata est, sit propositi et assignati. Et hoc quidem in contrariis est perspiciendum. Quoniam autem contrariorum plures sunt complexiones: verbi gratia, boni effectivum habet duas complexiones et corruptivum boni et effectivum mali, et amicis benefacere multis, sicut in praehabitis est ostensum, sumenda est ratio diffinitiva: quia talis facillime suscipitur a respondente: totas ergo diffinitiones considerandum est quemadmodum in praehabitis dictum est, particulariter sive ad partes diffinitionis respiciendum est hoc modo quo nunc dicemus.
TRACTATE II. ON DEFINITION.
CHAPTER I. How the problem concerning definition is constructed in common, and first through the place from opposites.
But if we wish to construct a problem concerning definition, then first one must know that no one or few syllogize a definition so as to conclude a definition. For only the demonstrator syllogizes a certain definition, as has been shown in the Posterior Analytics, a definition which states what and not why. But the dialectician does not syllogize a definition, that it is a definition; rather, concerning the predicate, he sometimes syllogizes from probabilities and as if from conjectures that it is present as definition. But disputants receive and suppose such a principle which is definition, and it is destroyed by them as by those who consider geometry and numbers; for they set definitions before, as also supposing a principle. And similarly this occurs concerning other teachable sciences, when it is on account of utility.
How definition comes to be is to assign a matter of another and higher business; for this is done in the seventh book of First Philosophy, where it is determined both what definition truly is and how one must define through quiddity and the principles of its substantial being. But now, as much as suffices for present utility, it must only be said that it is possible for definition to be made, and that this can be concluded of the defined thing and of the subject; and this belongs to the fact that there is a syllogism which shows definition to be concluded as predicate. And this is proved through the account of definition, for definition is speech which signifies what the being of a thing is; and therefore those things which are predicated through definition or as definition must be predicated in what it is of the defined thing alone, because unless they were predicated of the defined thing alone, the definition would not be convertible with the defined thing. Further it must be known that genera and differences are predicated of a thing in what it is; genus indeed because it states what, but difference states a quale, because it states what sort of thing as form makes what-being in the species, and therefore the species is a qualified what.
Therefore I say that by a dialectical syllogism a predicate is concluded to be present as definition: because if one of the disputants takes these, genus and difference, which alone are predicated of the thing, species, and subject in what it is, such a speech complex from genus and difference will of necessity be a definition, through the place from definition; for nothing else can be the definition than the defined thing from genus and difference, because nothing other than genus and difference is predicated of the thing in what it is. Therefore if it happens to syllogize that such speech which is from genus and difference is concluded of the subject, it has been proved that definition is concluded of the subject. Therefore it is manifest that a syllogism can be made from definition, that is, toward definition. But from what things one ought to construct and constitute definition has been determined more subtly in other places, both in the seventh book of First Philosophy and in the second book of the Posterior Analytics. For the proposed method, however, the same places which have been introduced for other predicates apply, because all other predicates are elementary toward the predicate of definition and are useful for constructing that something is present as definition.
Therefore first one must consider in common extrinsic places, among which the place from opposites is more efficacious. Therefore one must examine in contraries and in the other genera of opposites. I say that one examining must examine the whole accounts of opposites, and also particularly according to each. For if the opposite account or definition belongs to some opposite, then it is necessary that what has been said and assigned belong to the proposed and assigned thing. And this must be examined in contraries. But since there are several complexions of contraries, for example, productive of good has two complexions, both corruptive of good and productive of evil, and doing good to many friends, as was shown in what preceded, the defining account must be taken, because such an account is most easily received by the respondent. Therefore whole definitions must be considered as was said in what preceded; particularly, or with regard to the parts of definition, one must look in this way which we now state.
Primum in partibus diffinitionis considerandum per methodum de genere si recte genus assignatum est, quod positum est in diffinitione hoc modo. Duobus enim finitis contrariis propositis si unum eorum est in contrario genere, et propositum diffinitum non est in eodem genere cum suo contrario, palam statim est, quod est in genere illi contrario. Sicut contraria sunt distincta, ita contraria sunt genera in quibus sunt: et hoc est in omnibus moralibus contrariis, in quibus contrarietas sumitur medii ad extremum: necesse est enim omnia contraria vel in eodem genere, vel in contrariis generibus esse: naturalia quidem in eodem, et moralia in contrariis in quibus contrarietas est extremi ad extremum: in contrariis enim generibus sunt moralia, in quibus contrarietas sumitur medii ad extremum. Differentias autem (quae ponuntur in diffinitione) semper probamus contrarias de contrariis praedicari: quia differentia est forma, et contrariorum formae sunt contrariae: velut patet in albo et nigro, quorum differentiae sunt congregativum et disgregativum visus: esse album enim disgregativum visus est, nigrum autem congregativum. Propter quod si de contrario alicujus contraria praedicatur differentia, constat quod assignata et proposita differentia praedicabitur de proposito. Propter quod cum et genus et differentiae recte sunt assignata, palam est quia oratio ex his complexa diffinitio recta erit quae assignata est, et quod inest ut recta diffinitio. Sic ergo construitur diffinitio et ad totam diffinitionem et ad partes inspiciendo.
Aut forte aliquis dicet, quod hoc quod dictum est (quod contrariae differentiae praedicantur de his) indiget determinatione: non enim est verum generaliter, sed tantum de his contrariis quae sunt in eodem genere, ut album, et nigrum. Eorum autem contrariorum quorum genera sunt contraria, nihil prohibet eandem generalem differentiam de utrisque dici contrariis, ut de justitia et injustitia quae sunt in contrariis generibus: nam hoc quidem est virtus sive in genere virtutis, illa autem est vitium sive in genere vitii: propter quod patet quod haec differentia animae, quando dicitur virtus animae et vitium animae, de utrisque contrariis dicitur, et distinguit et separat haec differentia a corporis virtute et vitio: eo quod etiam quaedam virtus est corporis, et etiam vitium est corporis, ut in VII Ethicorum determinatur. Si ergo verum est, quoniam contrariorum aut oppositorum eaedem sunt differentiae probatae, si de contrario contraria differentia praedicatur, et eadem praedicatur de proposito, palam quoniam differentia (quae dicta est et assignata est) praedicabitur de proposito, et erit vera differentia ipsius: et sic ex uno genere et una differentia una diffinitio constituitur.
Universaliter autem ad construendum diffinitionem dicendum est: quia si diffinitio est ex genere et differentiis, tunc oportet quod si contrariorum diffinitio manifesta est, tunc etiam propositi diffinitio manifesta erit. Nam communiter contraria aut sunt in eodem genere, aut in contrario genere. Similiter, ut jam dictum est, et differentiae aut contrariae praedicantur de contrariis, aut eaedem de contrariis praedicantur: et palam est quoniam de proposito diffinito ut idem genus praedicabitur, quod etiam de suo contrario praedicatur: eo quod sunt in eodem genere: et tunc sunt differentiae contrariae vel omnes vel aliquae, saltem ultima et constitutiva: reliquae autem differentiae sunt eaedem generales.
First, in the parts of definition, it must be considered by the method concerning genus whether the genus placed in the definition has been assigned rightly in this way. For when two bounded contraries have been proposed, if one of them is in a contrary genus and the proposed defined thing is not in the same genus with its contrary, it is immediately plain that it is in the genus contrary to it. As contraries are distinct, so the genera in which they are are contrary; and this is so in all moral contraries, in which contrariety is taken from mean to extreme. For all contraries must be either in the same genus or in contrary genera: natural contraries in the same, and moral contraries in contrary genera, in which the contrariety is of extreme to extreme; for moral things are in contrary genera, in which contrariety is taken from mean to extreme. But the differences which are placed in definition we always prove to be predicated contrarily of contraries, because difference is form, and the forms of contraries are contrary, as is clear in white and black, whose differences are dispersive and contractive of sight; for to be white is dispersive of sight, but black contractive. Therefore if a contrary difference is predicated of the contrary of something, it is clear that the assigned and proposed difference will be predicated of the proposed thing. Therefore when both genus and differences have been rightly assigned, it is plain that the speech complex from these will be the right definition which has been assigned, and that it is present as the right definition. Thus definition is constructed by looking both to the whole definition and to the parts.
Or perhaps someone will say that what has been said, that contrary differences are predicated of these, needs determination. For it is not true generally, but only of those contraries which are in the same genus, such as white and black. But of those contraries whose genera are contrary, nothing prevents the same general difference from being said of both contraries, as of justice and injustice, which are in contrary genera; for this one is virtue or in the genus of virtue, while that one is vice or in the genus of vice. Therefore it is clear that this difference of soul, when virtue of soul and vice of soul are said, is said of both contraries, and this difference distinguishes and separates from virtue and vice of body, because there is also a certain virtue of body and also a vice of body, as is determined in the seventh book of the Ethics. Therefore if it is true that the same differences have been proved of contraries or opposites, if a contrary difference is predicated of the contrary and the same is predicated of the proposed thing, it is plain that the difference which has been stated and assigned will be predicated of the proposed thing and will be its true difference; and so from one genus and one difference one definition is constituted.
But universally, for constructing definition, it must be said that if definition is from genus and differences, then, if the definition of the contraries is manifest, the definition of the proposed thing will also be manifest. For commonly contraries are either in the same genus or in a contrary genus. Similarly, as has now been said, differences are either predicated contrarily of contraries, or the same are predicated of contraries. And it is plain that the same genus will be predicated of the proposed defined thing which is also predicated of its contrary, because they are in the same genus; and then the differences are contrary, either all or some, at least the final and constitutive one, while the remaining differences are the same general differences.
Aut diffinita sunt in genere contrario, ita quod unum in uno est genere, et reliquum in contrario est illius: et tunc differentiae sunt eaedem, genera vero contraria: aut ambo quidem sunt contraria et genera et differentiae. Nam ambo et genera et differentias easdem esse contrariorum non contingit: quia sic diffinitio contrariorum esset una, quod esse non potest. Sic ergo vero genere assignato et vera differentia, veram contingit astruere diffinitionem. Attendendum autem hic, quod quando contrariorum eadem differentia dicitur, quod hoc est praecipue in diffinitionibus passionum, in quibus subjectum se est loco differentiae, sicut in diffinitione aquili et simi, utriusque differentia est nasus: et sicut dictum est in diffinitione justitiae et injustitiae, cujus utriusque differentia est anima, de differentiis formaliter constitutivis hoc verum esse non potest, et caetera.
CAPUT II. Qualiter construitur problema de diffinitione per locum a casibus et conjugatis.
Amplius a casibus et conjugatis considerandum est consequentia in casibus et conjugatis, et genera esse generibus, et differentias differentiis, ex quibus sunt diffinitiones, et etiam totas diffinitiones a totum diffinientibus esse secundum casus et conjugata sumptas. Cujus exemplum est, ut si oblivio est amissio scientiae in principalibus, et oblivisci erit amittere scientiam in sumptis et conjugatis, et oblitum esse, amisisse scientiam in praeterito: unoquoque enim eorum quae dicta sunt in principali vel sumpto concesso, necesse est et reliqua conjugata illi concedere.
Similiter respiciendo in locum a corruptione sic, si corruptio per diffinitionem est dissolutio substantiae, corrumpere erit dissolvere substantiam a conjugatis et casibus, et corruptum aliquid facere, dissolutum facere erit, et si corruptivum est dissolutivum substantiae, erit tunc corruptio dissolutio substantiae. Similiter autem est etiam in aliis: propter quod unoquoque talium sumpto, et omnia reliqua illi conjugata conceduntur: et si unum quodlibet insit ut diffinitio, omnia alia ut diffinitiones inerunt.
Adhuc considerandum est ex similiter se habentibus in proportione ad invicem: nam si salubre est effectivum sanitatis secundum habitudinem causae efficientis, sequitur quod similiter euechivum est effectivum euechiae, et juvativum erit effectivum boni: haec enim omnia differentia similiter se habent ad invicem secundum habitudinem ejus causae efficientis: unumquodque enim horum quae dicta sunt, similiter se habet ad proprium finem qui est intentus in ipsis effectivis: et ideo si unius eorum est diffinitio esse effectivum proprii finis, etiam reliquorum singulorum sic erit diffinitio.
Amplius inspiciendo in locum a minori, construitur diffinitio ex magis et minus videtur inesse: et hoc fit quoties contingit construere duo ad duo comparata sive comparabilia secundum magis et minus accepta. Ut verbi gratia, si magis haec diffinitio esse videtur illius quam haec alia videatur esse illius alterius, et haec quae minus videtur esse, est diffinitio, sequitur quod haec quae magis esse videtur, erit diffinitio.
Or the defined things are in a contrary genus, so that one is in one genus and the other is in the genus contrary to it; and then the differences are the same but the genera contrary. Or both are contrary, both genera and differences. For it cannot happen that both genera and differences of contraries are the same, because in that way the definition of contraries would be one, which cannot be. Therefore with the true genus assigned and the true difference, it happens to build up a true definition. But here it must be noted that when the same difference of contraries is said, this is especially in definitions of passions, in which the subject is in place of difference, as in the definition of hooked and snub nose is the difference of each; and as was said in the definition of justice and injustice, whose difference for each is soul. This cannot be true of formally constitutive differences, and so on.
CHAPTER II. How the problem concerning definition is constructed through the place from cases and conjugates.
Furthermore, from cases and conjugates, one must consider the consequence in cases and conjugates, and that genera belong to genera and differences to differences, from which definitions are made, and that whole definitions from those defining the whole are taken according to cases and conjugates. The example is that if forgetfulness is loss of science in the principal terms, then to forget will be to lose science in the derivatives and conjugates, and to be forgetful will be to have lost science in the past; for when any one of the things which have been stated is conceded in the principal or derivative, the remaining conjugates of it must also be conceded.
Likewise by looking to the place from corruption in this way: if corruption by definition is dissolution of substance, to corrupt will be to dissolve substance from conjugates and cases, and to make something corrupted will be to make something dissolved; and if the corruptive is dissolutive of substance, then corruption will be dissolution of substance. Likewise it is also in other cases; therefore when any one of such things has been taken, all the remaining conjugates are conceded to it, and if any one is present as definition, all the others will be present as definitions.
Still, one must consider from things similarly related in proportion to one another. For if the healthy is effective of health according to the relation of efficient cause, it follows that similarly what is conducive to good condition is effective of good condition, and the helpful will be effective of good; for all these differences are similarly related to one another according to the relation of that efficient cause. For each of the things stated is similarly related to the proper end intended in those effective things; and therefore if the definition of one of them is to be effective of its proper end, the definition of each of the others will also be so.
Furthermore, by inspecting the place from the lesser, definition is constructed from more and less when it seems to be present; and this happens whenever it is possible to construct two things compared to two, or comparable things, received according to more and less. For example, if this definition seems more to be the definition of this thing than that other seems to be the definition of that other thing, and the one which seems less is a definition, it follows that the one which seems more to be so will be a definition.
A simili etiam sequitur constructio diffinitionis: si enim similiter sit haec illius diffinitio ut haec alterius, si una est diffinitio, sequitur quod et altera est diffinitio: quia similium simile est judicium, ut dicit Boetius. Hic autem locus nihil valet ad propositum, si una diffinitio ad duo comparetur diffinita. Similiter nec etiam valet duabus diffinitionibus comparatis ad unum simpliciter, sive secundum similitudinem ex magis et minus considerato: eo quod nec unam diffinitionem duorum nec duas diffinitiones unius possibile est esse.
Sunt hi loci qui dicti sunt a conjugatis et casibus in proportione ex simili et ex magis et minus opportunissimi ad construendam facile diffinitionem: et ideo maximas oportet istas retinere in memoria, et per exercitium habere paratos eosdem: eo quod isti utilissimi sunt ad plura problemata. Oportet etiam paratos habere illos locos qui maxime sunt communes sive ad plura valentes, sicut maxime sunt loci extrinseci: eo quod illi plus quam reliqui sunt maxime operativi conclusionum multarum. Ut, verbi gratia, inspicere in singularibus utrum omnibus conveniat diffinitio, et sic considerare speciem utrum secundum esse speciei data sit sic diffinitio, si simul conveniat secundum speciem diffinitio: propter quod secundum unitatem est species praedicta de singularibus. Unde et hic locus utilis est ad eos (hoc est, contra eos) qui ponunt formas esse, sicut prius dictum est: illi enim unitati specierum rationes singularibus non possunt adaptare.
Amplius diligenter considerandum si aliquis in diffinitione vel praedicatione aliqua transferens ad aliud, dixit nomen: quia sic omne praedicatum interimitur, ut in secundo hujus scientiae libro dictum est. Et considerandum si idem de eodem ut diversum praedicavit, et similiter si quis alius locus est communis et operativus sive efficax: illum enim semper proximum habere oportet ad disputantem, et praecipue ad problema diffinitionis, ad quod omnia alia elementa sunt vel elementaliter se habent: quia ex his in plures abundabit syllogismos.
CAPUT III. Qualiter difficilius est construere quam destruere diffinitionem et alia praedicata.
Consideratis jam omnibus problematibus qualiter terminantur destructive et constructive, comparando ea ad facultatem destruendi et construendi, dicimus primo communiter, quoniam difficilius est construere quam destruere diffinitionem. Hoc autem erit per ea quae post haec dicuntur manifestum. Et hoc ideo est, quia cognoscere perfecte diffinitionem et sumere eam quasi concessum ab interrogantibus sive opponentibus non est facile: eo quod multa valde requiruntur ad diffinitionem construendam. Sicut, verbi gratia, difficile est sumere, quoniam eorum quae sunt assignata in assignata diffinitione, hoc quidem est genus, illud autem differentia, et illud etiam quod in eo quod quid est, genus tantum et differentiae de diffinito praedicantur: sine his vero impossibile est fieri syllogismum ad diffinitionis terminationem. Hoc autem oportet diligenter considerare et invenire, quod nulla alia de re praedicantur in eo quod quid est, nisi ista: quod si etiam quaedam alia quam proprium
Construction of definition also follows from the similar: for if this is the definition of this just as that is of that, if one is a definition it follows that the other also is a definition, because the judgment of similars is similar, as Boethius says. But here this place has no value for the proposal if one definition is compared to two defined things. Likewise it also has no value when two definitions are compared to one thing simply, or according to likeness considered from more and less, because it is not possible for there to be one definition of two things nor two definitions of one thing.
These places which have been stated from conjugates and cases, in proportion, from the similar, and from more and less, are most opportune for easily constructing definition; and therefore one must retain these especially in memory and have them ready through exercise, because they are most useful for many problems. One must also have ready those places which are most common or valid for many things, as the extrinsic places especially are, because they are more operative of many conclusions than the rest. For example, to inspect in singulars whether the definition belongs to all, and thus to consider species whether the definition has been so given according to the being of the species, if the definition belongs at once according to the species; therefore the species is predicated of singulars according to unity. Hence this place is useful against those who posit forms, as was said before; for they cannot adapt the accounts of singulars to that unity of species.
Furthermore, one must diligently consider whether someone, in definition or some predication, transferring to another, has stated a name; because in this way every predicate is destroyed, as was said in the second book of this science. And one must consider whether he has predicated the same of the same as diverse, and likewise if there is any other place which is common and operative or efficacious; for the disputant must always have it nearby, and especially for the problem of definition, toward which all other elements are or are related elementally, because from these he will abound in more syllogisms.
CHAPTER III. How it is more difficult to construct than to destroy definition and other predicates.
With all problems now considered, how they are terminated destructively and constructively, comparing them to the faculty of destroying and constructing, we first say commonly that it is more difficult to construct than to destroy definition. This will be manifest through the things which are said after this. And this is so because perfectly knowing a definition and taking it as conceded by questioners or opponents is not easy, because very many things are required for constructing a definition. For example, it is difficult to take that, of the things assigned in the assigned definition, this is genus, but that is difference, and also that only genus and differences are predicated of the defined thing in what it is. Without these it is impossible for a syllogism to be made for the termination of definition. But one must diligently consider and find that no other things are predicated of the thing in what it is except these; and if also certain other things than proper
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