Abstract of Logic, Book 2 · Chapter 1 – Chapter 2
CHAP. I. Of Definition in General, and Definition Nominal.
Axiom 1. A Definition is ſaid to be an Oration, viz. Internal or External, that is, either in the Mind, or brought forth in Words, declaring what that is which is ſought.
1. §. Which conſiſteth in two Words at the leaſt: And therefore an Explication of one Name by another more known, as if one ſhould call a Rapier a Sword, cannot properly be call'd a Definition, but yet it muſt be referr'd to Definition, as we ſhall afterwards make appear. The Reaſon why Definition muſt be a Speech is plainly this: Such is the Imbecillity of our Minds, that by one Conception we cannot eaſily attain to the Eſſence of a thing. That Definition therefore might occur, that is, accommodate it ſelf to this Imbecillity, it diſtributes the thing into Parts, viz. Genus, and Difference, or the like, and ſo delivers it to be underſtood by the Mind by many Conceptions, calling each Part by its Name.
Ax. 4. Now of Definitions, the one is of the Name and the other of the thing.
Ax. 5. Definition of the Name is that which declares, what that is which is ſaid; or what is ſignified by the Name.
Ax. 6. And that either by Etymology, or a Conjugate, or a Synonymous Word. So that
1. §. Nominal Definition appears to be threefold, viz. that which is according to Etymology, and ſo declares the Signification of the Name out of the Original. As, a Triangle is that which has three Angles; Philoſophy is the Love of Wiſdom, &c. Or, Secondly, according to Conjugation; and declares the Name by a Conjugate Word; as, Quality is that by which Things are ſaid to be of what Quality they are. Or, Thirdly and Laſtly, According to Word; as, when an obſcure one is declared by one, or more, more known; as, a handſome Thing is one that is decent and honeſt, &c. For altho' when one Word is explained by another, it is improperly enough ſaid to be a Definition, becauſe ſuch Explication is not foreign, or an Oration as we have obſerv'd above, yet muſt ſuch an Explication be referr'd to Definition, as Ariſtotle ſays Book 1. Top. Cap. 5. And ſo we proceed to the next Chapter, viz. That.
CHAP. II. Of Perfect Definition.
Ax. 1. NOw Definition of the Thing is that which explains what the Thing it ſelf is.
Ax. 2. And is either Perfect or Imperfect.
Ax. 3. A Perfect, that which perfectly explains the Eſſence of the Thing by its Eſſential Attributes.
Ax. 4. Imperfect, not, at leaſt not Perfectly.
Ax. 5. The Laws of Perfect are principally Six, and the firſt is that the Definition be ſhort.
1. §. Now Definitions are ſaid to be ſhort when there is nothing leſs, nor more in 'em than there ought to be. Now that there may be ſomething more, may chiefly happen three Ways; and firſt, when a Tautology is committed; which is not only then when the ſame thing is repeated by a Synonymous Word; as if a Man ſhould be defin'd to be a Rational Animal, and endu'd with the Power of Underſtanding; which is the ſame thing in other Words; but alſo, when that is put into the Definition of the Species which ought to have been put into the Definition of the Genus: As if Blindneſs ſhould be defin'd to be a Privation of the Sight, which naturally ought to have in-been: For thoſe Words which naturally ought to have in-been, are Redundant, and included in the Word Privation it ſelf: That, Secondly, is otiosè, or unneceſſary in a Definition which diſtinguiſhes not the Defined from any other thing, as Tranſcendents; As if Virtue ſhould be defin'd to be that for which a Man ſhould be accounted Honeſt, &c. In this manner yet, are chief Genus's to be defin'd. In the third Place, that is ſaid to be otiosè in a Definition, which being taken away, the Definition would nevertheleſs be proper, and explain the Nature of the Thing; as if a Man ſhould ſay of a Man, that he was a Rational Animal capable of Diſciplines: For al tho' that of Capable of Diſciplines ſhould be withdrawn, yet the reſt of the Definition would be proper to explain the Eſſence of Man, &c.
Ax. 6. Secondly, Definitions ought to be Perſpicuous.
1. §. The Perſpicuity of Definitions, ſays the Prince of Philoſophers, ought to be ſuch as that it may preſently appear what that is which is taught: Nay, that from it, that of the Thing contrary alſo may be collected. All thoſe things therefore are to be avoided, which may any ways beget Obſcurity; as, Unuſualneſs, Ambiguity, Metaphor, &c. But if there be none proper, or elſe if any Word be more uſed in the Metaphorical than it is in the Proper Signification, nothing hinders but that we may adhibit a Metaphorical Word in a Definition. And therefore when Logick is defin'd to be an Art of Diſputing well, expreſſing by the Word Diſſerendi, ſignifying properly ſomething elſe; that Definition is improperly rejected for the Metaphor; becauſe the Word Diſſerendi is much ſeldomer uſed in its proper Signification, which is to diſtribute or diſperſe, than in the Metaphorical; tho' ſomething elſe poſſibly there may be, which may be reprehended in that Definition.
Ax. 7. Thirdly, Definitions ought to be Reciprocal with the Defined.
1. §. That is, whatever is contain'd in the Defined ought alſo ſo to be in the Definition; and ſo on the contrary. Wherefore when the Lawyers define natural Right to be that which Nature has taught all living Things, the Definition is too lax: For Right conſiſts only amongſt Men, and appertaineth not to Brutes. On the other ſide, when Logick is defined to be an Art of Diſputing or Arguing well, the Definition is too ſtreight: For Logick is not only a diſputing or Art of Diſputing, but alſo Defining, Dividing and Ordering well, which are not ſufficiently contained under that Notion of Diſputing.
Ax. 8. Fourthly, Definitions are to be affirmed.
1. §. For that Negative Definitions do not ſo much explain what a Thing is, as what it is not: Wherefore Ariſtotle having propos'd two Definitions of Accident, Book 1. Top. Cap. 5. preferrs the latter before the former, becauſe conceiv'd by Negation. Often yet are we forc'd thro' the Inopy of Words, or Imbecillity of our Underſtanding, or Imperfections of things, to make uſe of Negative Definitions; as, when we define an Angel to be a Finite Subſtance, void of Body, a Beaſt, an Irrational Animal; Blindneſs a Privation of Sight. But then they are Imperfect Definitions.
Ax. 9. Fifthly, Definitions ought to be propos'd without Copulation or Conjunction of Parts.
1. §. For a Definition is the Explication of one Eſſence, and therefore it ought to be one and that a ſimple Oration; But Copulative and Disjunctive Particles connect many together. For Example: A Man is not to be defin'd a Terreſtrial Animal and two-footed, but a Terreſtrial two-footed Animal; as is collected Cap. 5. of the Interpret. and Cap. 4. Book 2. of the Poſt. After the ſame manner Number is not to be defin'd, a Multitude even or uneven: For this is its Diviſion, but a Collection of Unites. But ſuch Definitions as theſe are frequently to be diſpens'd with, not becauſe perfect, but becauſe there are no perfecter: as when Book 2. of the Phyſ. Nature is defin'd to be the Principle and Cauſe of Motion and Quiet; and Enunciation Cap. 4. of the Book of Interp. an Oration pronouncing true or falſe.
Ax. 10. Sixthly, Definitions are to conſiſt of Prior Attributes, and ſimply more known, and alſo Indemonſtrable.
1 §. This Canon does the Philoſopher explain and confirm in the 6th Book of the Top. Cap. 4. to this Effect. Definition is given us, ſays he, that we may know: But we know not from every thing or all: but from thoſe that are Prior and more known. Now then ſince Definition may conſiſt either of them, which are to us more known, or ſimply: We ought rather to endeavour that the latter may be made known by the former, and ſimply more known than on the contrary; becauſe this manner of Defining is the moſt accommodate to Science. But yet amongſt thoſe who are incapable of ſuch Definitions it may be neceſſary, it may be, to make Definitions of thoſe that are more known to us, rather than thoſe that are more known in themſelves. But ſuch Definitions declare not the Eſſence of a thing, and therefore are imperfect; unleſs the ſame thing happen to be more known to us, and more known in it ſelf. But neither muſt a perfect Definition conſiſt only of thoſe that are more known, but alſo Indemonſtrable: For Definition is the Principle of Demonſtration, as is ſaid Book 1. of the Soul, Cap. 1. and Book 1. Poſt. Cap. 1. It is taught that the Principles of Demonſtration are immediate; which, certainly could not be, if their Parts were to be demonſtrated by former Cauſes.
Ax. 11. A perfect Definition conſiſts of the next Genus and Specifick Difference.
1. §. This Canon is precepted Book 6. Top. Cap. 1. But yet if the next Genus want a Name, there is added in its Place a Remote with a Difference to limit it, and make it a next Genus. So when an Animal is deſin'd to be a Living, Feeling, Corporeal Subſtance; Living Corporeal Subſtance is put in place or lieu of a next Genus, and the ſpecifick Difference is Feeling.
Ax. 12. The Difference of Subſtances, if not without, is always taken from their Form; but if without, or that Form be unknown, Propriety is added in the ſtead of Form.
1. §. So when Man is defined to be a Rational Animal, the Difference is taken from his Form, which is a Rational Soul. But becauſe incorporeal Subſtances have none, and the Specificks of Corporeal, even lye hid; becauſe of themſelves they incurr not our Senſes in the Place of Form, ſome Property muſt be taken; as, An Angel is an Incorporeal Subſtance, a Dog a Barking-Beaſt, &c.
Ax. 13. The Differences of Accidents are not taken from their Form or Eſſence, but their reſpect to their Subject, Object, Cauſe Efficient or Final, or ſomewhat elſe not contain'd in the Eſſence.
1. §. Which is the Cauſe, or Reaſon why Ariſtotle Book 6. of the Metaph. Cap. 5. ſays, that Subſtances are ſimply and primarily defin'd; Accidents ſecondarily only, or according to ſomething; and that the Definitions of Accidents are Orations through Additions, becauſe thoſe things that are added to their Genus in their Definitions are without their Eſſence; and almoſt of another Category.
Ax. 14. Proprieties are defin'd by Genus, Subject and next Cauſe; and that either Efficient, Final or both.
1. §. And firſt, Efficient, as an Eclipſe of the Moon is a Defect of Light in it by Reaſon of the Earth's being Diametrically interpoſed between the Sun and it: Thunder is the Noiſe of a broken Cloud by reaſon of the Fire's being oppreſs'd; and ſo 2dly Final; as, Senſe is a Natural Faculty in an Animal, for the End of Judging betwixt Singulars: The Appetite for the gaining of what is good to its ſelf, and avoiding what is Evil; or both, as the Act of Reſpiration is a Reciprocal Attraction and Expulſion of the Air by the Lungs, for the Refreſhment of the Heart, &c. The Subject now's ſometimes in a Definition of Proprieties unmentioned; becauſe it is contained either in the Genus or next Cauſe: As, the Memory is an internal Senſe, conſerving of the Images of things known. Here the Subject of Memory is not expreſs'd, to wit, Animal, becauſe contain'd in the Word Senſe, and expreſs'd in the Definition of that. So alſo Riſibility is a nanural Faculty of Laughing, ariſing from a Rational Animal. I ſay not of Man, becauſe ſufficiently underſtood, when I ſay ariſing from a Rational Animal, &c.
Ax. 15. Accidents improper, beſides the Genus, take to themſelves in Definition, in the Place of Difference, either Subject or Object, Cauſe Efficient or Final, or ſomething that is made out of theſe, But,
1. §. The manner of defining of theſe is ſcarcely to be contained within any certain Rules: For, ſome are defined by Genus and Subject, as, Simity is the Crookedneſs of the Noſe. Some Genus and Object as, Phyſick is the Science of Natural Body. And after this manner Theoretical Sciences; and ſome again by Genus and End; as, Grammar is the Art of ſpeaking well: Alſo Genus, End and Object; as, Logick is an Art of making of Inſtruments, and therewith directing the Underſtanding in the Knowledge of Things; or Liberality is a Virtue obſerving a Mediocrity in giving and receiving of Moneys, &c. After this manner Arts and Habits Moral. Some laſtly, by Genus and Cauſe Efficient; as, Whiteneſs is a Colour ariſing from a Predomination of Clear. Sound, a Patible Quality ariſing from a Stroke of the Air between two Bodies collided, or hit one againſt another. And after this manner all Patible Qualities, if not proper, of other Genus's of Accidents there can ſcarce be given any certain Rules; but each how they are to be deſin'd, Uſe and Examples of approved Authors muſt teach; which for this End the Studious of Logick ought to collect together.
Ax. 16. The Parts of Definition are always ſo to be plac'd, as that the Genus may precede the Difference; and every Word following may limit its foregoing.
1. §. So teaches Ariſtotle Book 2. Poſt. Cap. 13. For Example: An Animal is not to be defined a Feeling Animate; but an Animate Feeling Body; &c and ſo we come to Imperfect Definition.