Authors/Ockham/Summa Logicae/Book III-2/Chapter 28

Latin	English
CAP. 28. QUOMODO TERMINATUR QUAESTIO QUID EST; ET PRIMO DE DEFINITIONE.	Chapter 28. How the question what something is settled, and first on definition
Viso quomodo terminatur quaestio si est, videndum est quomodo terminatur quaestio quid est. Et hoc est in sciendo quomodo potest evidenter cognosci propositio in qua praedicatur definitio de definito.	Having seen how the question of "if it is" is settled, we must see how the question of "what it is" is settled. And this is in knowing how the proposition in which the definition is predicated of the defined can be clearly cognised.
Est autem primo sciendum quod definitionum quaedam est definitio exprimens quid nominis et quaedam est definitio exprimens quid rei. Definitio exprimens quid rei est illa definitio quae non est necessaria disputanti scienti significatum vocabuli; sicut ad hoc quod aliquis sciat quid significat hoc nomen ‘homo’, non est necessarium scire quod homo componitur ex tot partibus vel ex talibus partibus. Unde quilibet potest disputare cum alio, quamvis ignoret definitionem exprimentem quid rei, sed ignorata definitione exprimente quid nominis non potest ƿ quis cum alio disputare.	But first of all it must be known that one [sort of] definition expresses the nominal essence and another expresses the real essence. A definition expressing the real essence is that definition which is not necessary to the disputant who knows the meaning of the term; just as in order for someone to know what the name 'man' signifies, it is not necessary to know that man is composed of so many parts or of such parts. Therefore anyone can argue with another, although he is ignorant of the definition expressing the real essence, but being ignorant of the definition expressing the nominal essence, no one can argue with another.
Et ideo quando quis addiscit significata vocabulorum, tunc addiscit definitiones exprimentes quid nominis, quamvis non addiscat definitiones exprimentes quid rei. Non est igitur definitio exprimens quid rei necessaria disputanti, quia talis non tantum exprimit quid nomen significat, sed etiam exprimit quid res est.	And therefore when someone learns the meanings of terms, he learns the definitions expressing the nominal essence, although he does not learn the definitions expressing the the real essence. Therefore the definition expressing the real essence is not necessary for the disputant, because such a definition does not only express what the name signifies, but what the real essence is.
Talis autem definitio duplex est.	But such a definition is twofold.
Quaedam enim definitio talis est quae nihil importat extrinsecum rei alio modo quam importat rem vel partem rei. Et talis definitio vocatur definitio propriissime dicta, quae non potest esse nisi substantiarum vel nominum substantiarum, quia talis definitio non potest esse nisi compositorum, tamquam illorum quorum essentia exprimitur per orationem, cuiusmodi composita per se una non sunt nisi substantiae.	For one definition conveys nothing external to a thing in any other way than it conveys a thing or a part of a thing. And such a definition is most properly called a definition, which can only be of substances or the names of substances, because such a definition can only be of composites, as those whose essence is expressed by speech, of which sort composites per se one are only substances.
Talis definitio est ista ‘animal rationale’; sit ‘animal’ genus et ‘rationale’ differentia, quia ‘animal’ importat totum hominem et ‘rationale’ importat partem hominis sicut suum abstractum.	Such a definition is 'rational animal'; let 'animal' be the genus and 'rational' the differentia, because 'animal' imports the whole man and 'rational' implies a part of man as its abstract.
Alia est definitio importans quid rei, quae simul cum hoc quod importat rem, importat vel exprimit aliquid quod non est de essentia rei; sicut definitio animae, quae est ista ‘actus corporis physici organici’ etc. importat animam et corpus, quod non est pars animae nec anima.	Another definition importing of the real essence, which, at the same time as that which imports a thing, conveys or expresses something which is not of the essence of the thing; as the definition of the soul, which is 'act of the organic physical body' etc. It signifies the soul and the body, which is neither part of the soul nor the soul.
Et ista vocatur definitio per additamentum. Et tales definitiones importantes quid rei convertuntur cum nominibus mere absolutis affirmativis.	And this is called definition by addition. And such definitions importing the real essence are converted into purely positive absolute names.
Aliae sunt definitiones importantes quid nominis, quae non sunt nisi orationes exprimentes quid significant nomina. Et tales definitiones propriissime sunt nominum negativorum et connotativorum et respectivorum, sicut ista definitio ‘habens albedinem’ sive ‘informatum albedine’ non exprimit nisi quid significat hoc nomen ‘album’.	There are other definitions importing the the nominal essence, which are nothing but statements expressing what the names mean. And such definitions are very proper of negative and connotative and respective nouns, just as the definition 'having whiteness' or 'informed by whiteness' does not express anything other than what this word 'white' means.
Unde ista definitio est necessaria cuilibet cum alio disputanti.	Hence this definition is necessary for anyone disputing with another.