Authors/Ockham/Summa Logicae/Book I/Chapter 23

Latin	English
[1.23. DE DIFFERENTIA]	[Chapter 23. On differentia]
Tertia species universalium est differentia. Quae ut sciatur perfectius, sciendum est quod, sicut dicit Porphyrius, hoc nomen differentia tripliciter accipitur, scilicet communiter, proprie et magis proprie.	The third species of universals is the differentia. In order that this be known more perfectly, it should be known that, as Porphyry says, the name differentia can be taken in three ways, namely commonly, properly, and more properly.
Communiter dicitur differentia omne illud quod non praedicatur in quid de aliquo, praedicatur tamen de eo et ab alio removetur. Et differentia sic accepta communis est ad differentiam magis proprie dictam et ad proprium et ad accidens. Unde commune est ad tres species universalium, scilicet differentiam, proprium et accidens.	Commonly, whatever is not predicated in quid of anything is called a differentia, yet it is predicated of one and removed from another. And differentia, thus understood, is common more to differentia in the proper sense, and to property and to accident. Hence it is common to the three species of universals, differentia, property and accident.
Proprie dicitur differentia illud quod est proprium uni et non potest competere alteri. Vel, secundum Porphyrium, differentia proprie dicta est illud quod competit alicui, et non potest sibi exsistenti successive competere et non competere; quod vocatur accidens inseparabile, de quo dicetur inferius.	A differentia is called a property when it is proper to one thing and cannot belong to another. Or (according to Porphyry), a differentia in the proper sense is what belongs to something, and cannot successively belong and not belong to it. This is called an ‘inseparable accident’, which will be discussed below.
Differentia vero magis proprie dicta est differentia specifica.	But a differentia in the proper sense is a ‘specific difference’.
Potest autem et alia divisio differentiae assignari, quae tamen praecedenti non repugnat, ut dicatur quod hoc vocabulum ‘differentia’ potest quadrupliciter accipi, scilicet stricte, large, largius et largissime.	Another division of differentia can be assigned, which is nevertheless does not clash with the above, as it is said that the word ‘differentia’ can be understood in four ways, namely in the narrow, broad, broader, and broadest sense.
Stricte dicitur differentia quae per se primo modo praedicatur de aliquo, et non indicat aliquid extrinsecum rei, pro qua supponit illud de quo praedicatur. Et sic est unum quinque universalium, de quo in hac parte loquendum est.	A differentia in the narrow sense is when it is predicated per se of something in the first mode, and does not indicate something extrinsic to the thing for which that of which it is predicated supposits. And thus it is one of the ‘five universals’, of which we have spoken in this part.
Large dicitur differentia illud quod necessario praedicatur de aliquo, quod non omnibus potest convenire. Et sic potest dici quod ‘risibile’ est differentia hominis, quia haec est necessaria ‘homo est risibilis’.	In the broad sense, a differentia is what is necessarily predicated of something, which cannot belong to all things. And thus it can be said that ‘capable of laughter’ is a differentia of man, because ‘man is capable of laughter’ is necessary.
Largius dicitur differentia illud quod praedicatur de aliquo et non potest virtute naturae successive affirmari et negari de illo, [illo] remanente. Et tale vocatur accidens inseparabile.	In the broader sense, a differentia is what is predicated of something and which cannot in virtue of its nature be successively affirmed and denied of it, while it continues to exist. And such is called an ‘inseparable accident’.
Largissime dicitur differentia omne illud quod praedicatur de uno et non de omnibus. Et sic etiam accidens separabile dicitur diiferentia. Sicut si Sortes sit albus et Plato niger, dici potest quod ‘album’ est differentia Sortis, quia Sortes est albus et non Plato.	In the broadest sense, a differentia is everything which is predicated of one and not of all. And in this way also a separable accident is called a differentia. For example, if Socrates is white, and Plato is dark, it can be said that ‘white’ is a differentia of Socrates, because Socrates is white and not Plato.
Dimittendo autem pro nunc ista ultima membra, dicendum est de primo.	Dismissing for now the last member, we should talk about the first.
Et est intelligendum quod differentia non est de essentia rei, sed est quaedam intentio animae, praedicabilis de contentis non in quid. Quae intentio ideo dicitur differentia quia cum non praedicetur in quid, est tamen medium concludendi negativam, in qua negatur illud cuius est differentia ab alio. Sicut ‘rationale’ est medium concludendi negativam, quae negat hominem ab asino et aliis quae non sunt homines, sic arguendo ‘omnis homo est rationalis; nullus asinus est rationalis; igitur nullus asinus est homo’.	It should be understood that a differentia is not of the essence of a thing, but is a certain intention of the soul, predicable of those subsumed under it, but not in quid. This intention is therefore called a differentia because, while it is not predicate in quid, it is nonetheless a medium of concluding a negative, in which that of which it is a differentia is denied of another. For example, ‘rational’ is a medium of concluding a negative, which denies ‘man’ of donkey and of others which are not men, in arguing ‘every man is rational, no donkey is rational, therefore no donkey is a man’.
Unde non est imaginandum quod differentia est aliquid intrinsecum speciei per quod una species distinguitur ab alia; tunc enim differentia non esset universale, sed esset materia vel forma vel totum compositum ex materia et forma. Sed differentia est quoddam praedicabile proprium uni speciei et non conveniens alteri, et vocatur differentia essentialis, non quia est de essentia rei, sed quia exprimit partem essentiae rei et nihil extrinsecum rei.	Hence it should not be imagined that a differentia is something intrinsic to a species through which one species is distinguished from another, for then a differentia would not be a universal, but would be matter or form or a whole composed of matter and form. But a differentia is a certain predicable proper to one species and not belonging to another, and is called an essential differentia, not because it is of the essence of the thing, but because it expresses part of the essence of the thing, and nothing extrinsic to the thing.
Unde differentia, de qua est nunc sermo, semper exprimit partem rei, et aliqua differentia exprimit partem materialem, aliqua exprimit partem formalem. Sicut ista differentia hominis ‘rationale’ exprimit animam intellectivam, ad modum quo ‘album’ exprimit albedinem et ‘animatum’ animam. Haec autem differentia ‘materiale’ exprimit, consimiliter et proportionaliter materiam et eodem modo quo ‘animatum’ animam. Et ideo eodem modo est differentia. Et ideo falsum est de vi vocis quod multi moderni dicunt quod differentia accipitur tantum a forma et non a materia, quia differentia ita accipitur a materia sicut a forma.	Hence differentia, which is is the subject of this discourse, always expresses part of a thing, and some differentia expresses a material part, some expresses a formal part. For example, the differentia ‘rational’ expresses the intellective sould, in the manner that ‘white’ expreses whiteness and ‘animate’ expresses the soul. But the differentia ‘material’ expresses – similarly and correspondingly – matter, and in the same way that ‘animate’ expresses the soul. And therefore in the same way is differentia. And therefore it is literally false what many moderns say, that differentia is understood only according to form and not according to matter, because differentia is understood according to matter just as according to form.
Quamvis tamen aliqua differentia accipitur a materia et aliqua a forma, omnis tamen differentia quando ponitur in definitione assimilatur formae. Quia sicut forma advenit materiae et praesupponit eam, ita omnis differentia in definitione advenit generi, et primo ponendum est genus, secundo differentia, sive differentia ponenda accipiatur a forma sive a materia. Unde si corpus debeat definiri, sic debet definiri ‘corpus est substantia materialis’, ubi primo ponitur ‘substantia’ tamquam genus, secundo ‘materialis’ tamquam differentia, et tamen sumitur [a materia] et importat principaliter materiam.	Nevertheless, although some differentia isunderstood according to material, and some according to form, still every differentia when it is given in a definition is assimilated to form. For, just as form is applied to matter and presupposes it, so every differentia in a definition applies to the genus, and the first to be given is the genus, second the differentia, whether the differentia to be given is understood according to form or according to matter. Hence, if body ought to be defined, it ought to be defined as “body is a substance that is material”, where ‘substance’ is given first, as if a genus, and second ‘material’ as if a differentia, and yet it is taken according to matter, and principally conveys matter.
Ex praedictis sequitur quod nulla species, quae est praecise communis simplicibus carentibus compositione ex materia et forma, habet differentiam essentialem, quia non habet partem, quamvis multas possit habere differentias accidentales. Ex isto sequitur ulterius quod nulla species, quae est praecise simplicium, est definibilis definitione proprie dicta sive sit in genere substantiae sive in quocumque alio praedicamento, quamvis definitione data per additamentum talis species definiri possit.	From what has been said, it follows that no species, which is precisely common to simple things lacking composition from matter and form, has essential differentia, because it does not have parts, although it can have many accidential differentiae. From this it furthermore follows that no species, which is precisely of simples, is definable by a definition properly so-called, whether in the genus of substance or in any other category, although by a definition given by addition, such a species can be defined.
Et ideo omnes auctoritates quae volunt quod omne genus dividitur per differentias et quod species habet differentiam constitutivam et huiusmodi, dupliciter exponi possunt. Uno modo ut loquantur tantum de generibus et speciebus habentibus differentias tales, ut sensus istius ‘omne genus dividitur per differentias’ sit iste ‘omne genus habens differentias tales per eas dividitur’. Aliter exponi possunt, ut omnes tales propositiones auctorum intelligantur accipiendo indifferenter differentiam pro differentia essentiali et accidentali, sive pro differentia stricte et largius dicta.	Therefore all authorities who wish that every genus is divided by its differentiae, and that a species has a constitutive differentia and so on, can be expounded in two ways. In one way, as they are speaking only of genus and species having such differentiae, so that the sense of “every genus is divided by differentiae” is “every genus having such differentiae is divided by them”. In another way it can be expounded, so that all such propositions of the authors are understood by understanding differentia indifferently for essential and accidental differentia, whether for differentia understood in the narrow or broader sense.
Ulterius sciendum est quod per tales propositiones ‘differentia est qua abundat species a genere’, ‘differentia est constitutiva speciei’, ‘differentia dividit genus in suas species’, ‘differentia est illud quo differunt singula’, ‘differentia est pars speciei’, et per huiusmodi, non intelligunt auctores quod differentia sit aliquid reale in specie, sed praecise intendunt quod differentia est praedicabile proprium alicui, quod debet esse pars definitionis ipsius.	Furthermore, it should be known that by such propositions as “the differentia is how the species flows from the genus”, “the differentia divides the genus into its species”, “the differentia is that by which singulars differ”, “the differentia is part of a species” and so on, the authors do not intend that a differentia is something real in the species, but they precisely intend that differentia is a predicable proper to something, which ought to be part of its definition.
Et ideo ‘species differentia abundat a genere’, hoc est differentia ponitur in definitione speciei et non in definitione generis. Similiter ‘differentia est constitutiva speciei’, hoc est differentia complet definitionem speciei. Similiter ‘differentia est illud quo differunt singula’, hoc est differentia est propria per praedicationem uni et non alteri, et est medium concludendi unum negari ab alio. Similiter ‘differentia est pars speciei’, hoc est differentia exprimit partem illius quod significatur per speciem vel est pars definitionis quae significat idem quod species. Similiter, quando dicit Porphyrius quod differentiae sunt potestate in genere, non intendit nisi quod differentia non praedicatur de genere universaliter sumpto sed tantum particulariter sumpto.	And therefore “the species flows from the genus by the differentia” – that is, “the differentia is given in the definition of the species and not in the definition of the genus”. Similarly “the differentia is constitutive of the species” – that is, the differentia completes the definition of the species. Similarly “the differentia is that by which singulars differ” – that is, the differentia is proper to one thing by predication, and not to another, and is the medium of concluding that one is denied of another. Similarly “the differentia is part of the species” – that is, the differentia expresses part of that which is signified by the species or is part of the definition which signifies the same as the species. Similarly, when Porphyry says that differentiae are in the genus by potentiality, he means only that the differentia is not predicated of the benus universally taken, but only particularly taken.
Est igitur differentia quaedam intentio animae, exprimens determinatam partem rei, praedicabilis in quale de eisdem de quibus species, cum qua convertitur, praedicatur in quid. Quod autem differentia sit quaedam intentio animae, patet per hoc quod est quoddam universale. Sed universale, sicut ostensum est prius, non est nisi intentio animae nisi forte signum voluntarie institutum vocetur universale; sed de tali universali, quod est ad placitum universale, nunc non loquor, sed de illo quod ex natura sua habet quod sit universale.	Differentia is therefore a certain intention of the soul, expressing a determinate part of a thing, predicable in quale of the same things of which the species, with which it is converted, is predicated in quid. But that a differentia is a certain intention of the soul, is clear from the fact that it is a sort of universal. But a universal, as was shown before, is nothing but an intention of the soul – unless perhaps a sign instituted by convention is to be called universal, but of such a universal, which is a universal by convention, I do not speak now, but rather of that which has being universal from its nature.
Quod sit exprimens partem rei patet, quia oportet quod significet aliquid a parte rei. Et non significat praecise totum, quia tunc nullo modo distingueretur a specie; igitur significat partem rei vel aliquid extrinsecum. Sed nullum extrinsecum significat, quia tunc esset proprium vel accidens; relinquitur igitur quod significat partem rei. Unde semper differentia exprimit partem rei, isto modo quo album exprimit albedinem.	That it is expresses a part of the thing is clear, because it has to signify something a parte rei. And it does not signify precisely the whole, because in no way would it then be distinguished from the species. Therefore it signifies either part of the thing, or something extrinsic. But it signifies nothing extrinsic, because then it would be a property or accident. It remains, therefore, that it signifies a part of the thing. Hence differentia always expresses a part of the thing, in the way that ‘white’ expresses whiteness.
Et ideo semper differentia est unum concretum, vel deberet esse concretum, cui correspondere deberet unum abstractum, significans praecise partem rei, ad modum quo albedo correspondet albo; et semper illud abstractum deberet supponere pro parte et concretum pro toto composito ex alia parte et illa.	And therefore differentia is always a concrete term, or ought to be a concrete term, to which there ought to correspond an abstract term, signifying precisely a part of the thing, in the way that whiteness corresponds to white, and always that abstract term ought to supposit for the part, and the concrete term for the whole composed from the other part and that part.
Quod autem differentia praedicatur in quale patet, quia per differentiam non respondetur ad quaestionem factam per quid de aliquo, sed per quale. Si enim quaeras, qualis est homo, convenienter respondetur quod est rationalis vel materialis; praedicatur igitur in quale, et de eisdem praedicatur de quibus praedicatur species, quia convertibilis est cum specie. Ex quo patet quod nullo modo concedendum est quod anima est differentia corporis, sed animatum; nec ratio est differentia hominis, sed rationale.	But it is clear that differentia is predicated in quale, because a differentia is not an answer to the question ‘what’ asked about something, but ‘what kind’. For if you ask what kind of thing a man is, the appropriate reply is that a man is rational or material. Therefore it is predicated in quale, and it is predicated of the same things of which the species is predicated, because it is convertible with the species. From this it is clear that in no way should it be conceded that the soul is a differentia of the body, but rather ‘animated’. Nor is ‘reason’ a differentia or man, but ‘rational’.