Abstract of Logic, Book 2 · Chapter 4
CHAP. IV. Of the Manner of Inveſtigation or Quaeſt of Definition.
Ax. 1. DEfinitions are collected from Diviſion or Induction, or Demonſtration or Etymology, or Derivation, or, Laſtly, from the Definition of the Contrary.
COMMENTARY.
1. §. And by way of Diviſion thus, when Diviſion being made of the chief Genus, and Subordinate Species's under which the Defined is contained, as far as the Defined it ſelf, all the Eſſential Attributes are collected, out of which its Definition is to be framed. After this manner let us ſearch for the Definition of Man. Man is a Subſtance; but becauſe an Angel is alſo a Subſtance; That it may appear how Man differs from an Angel, Subſtance ought to be divided into Corporeal and Incorporeal. A Man is a Body, an Angel without a Body: But a Stone alſo is a Body: That therefore a Man may be diſtinguiſhed from a Stone, divide Bodily or Corporeal Subſtance into Animate and Inanimate, that is, with or without a Soul. Man is a Corporeal Subſtance Animate, Stone Inanimate. But Plants are alſo Animate: Let us divide therefore again Corporal Subſtance Animate into Feeling and void of Feeling. Man feels, a Plant not: But a Horſe alſo feels, and likewiſe other Beaſts. Divide we therefore Animate Corporal Feeling Subſtance into Rational and Irrational. Here therefore are we to ſtand, ſince it appears that every, and only Man is Rational. From hence therefore may be collected this Definition, viz. That Man is a Corporeal Subſtance, Living, Feeling Rational; or leſt in Definition of the Species be put the Definition of the Genus; a Rational Animal. This Method Ariſtotle delivers Book 2. Poſt. Cap. 13. and there adviſes in this Series of Diviſion, no Eſſential Difference be paſs'd by: I add alſo that no Accidental muſt be adhibited.
2. §. By Induction thus, viz. when the Eſſential Attributes of them contain'd under the Defined being compared together, rejecting thoſe that appear proper to the Singulars, the Definition is confected of the reſt, which are common to all. Seek we thus the Definition of Animal. Under Animal are contain'd Man, Horſe, Lion, &c. The Eſſential Attributes of theſe, are Corporeal Subſtance, Living, Feeling: Theſe are common to all. The Property of Man is to be Rational: Irrational is common to the Horſe and Lion. The Property of a Horſe is to whinny; Lion to roar: That therefore you may find the Definition of Animal; Rational, Irrational, Whinnying, Roaring, are to be rejected, as being too ſtreight. From the reſt ſuch a Definition as this will ariſe, viz. That an Animal is a Living, Feeling, Corporeal Subſtance, &c. This Method Ariſtotle delivers in the Place now laſt cited.
3. §. Demonſtration is hereafter to be treated of.
4. §. As for Etymology, it often ſupplies the Place of the Difference of Things, which with the Genus may Conſtitute a Definition. So becauſe Arithmetick is ſo ſaid, foreign, that is, from Number, it's collected that Arithmetick is the Science of Numbers: And Phyſick, foreign, that is, Nature, it's collected that Phyſick is the Natural Science, or Science of Nature, &c.
5. §. From Derivation a Definition is collected, when from the Definition of one Conjugate the Definition of another is collected; as the Definition of Prudence from that of a prudent Man.
6. §. From the Definition of one Contrary alſo, may be collected that of another: For of Contraries, the Science is the ſame. And, therefore, when Ariſtotle Book 3. Cap. 1. had defin'd an unvoluntary Thing to be that which is either done by Force or Ignorance, and affirmed that to be done by Force whoſe Principle is External, and ſuch, as that he contributes nothing to it, who does or ſuffers it. He thence collects, that a voluntary Thing is that whoſe Principle is in him who acts and is not ignorant of the Circumſtances of the Fact, &c. Hence then proceed we to the Conſideration of the next to be conſidered, viz. Diviſion, its Laws and Species's, which will be the Subject of the next Chapter.