424 



OPERATIONS SUBSIDIARY TO INDUCTION. 



the places themselves agree in being 

 situated in that ellipse. We have, 

 therefore, by the same process which 

 gave us the description, obtained the 

 requisites for an induction by the 

 Method of Agreement. The succes- 

 sive observed places of the earth 

 being considered as effects, and its 

 motion as the cause vv^hich produces 

 them, we find that those effects, that 

 is, those places, agree in the circum- 

 stance of being in an ellipse. We 

 conclude that the remaining effects, 

 the places which have not been ob- 

 served, agree in the same circum- 

 stance, and that the law of the motion 

 of the earth is motion in an ellipse. 



The Colligation of Facts, therefore, 

 by means of hypothesis, or, as Dr. 

 Whewell prefers to say, by means of 

 Conceptions, instead of being, as he 

 supposes, Induction itself, takes its 

 proper place among operations sub- 

 sidiary to Induction. All Induction 

 supposes that we have previously 

 compared the requisite number of 

 individual instances, and ascertained 

 in what circumstances they agree. 

 The Colligation of Facts is no other 

 than this preliminary operation. When 

 Kepler, after vainly endeavouring to 

 connect the observed places of a planet 

 by various hypotheses of circular mo- 

 tion, at last tried the hypothesis of 

 an ellipse and found it answer to 

 the phenomena ; what he really at- 

 tempted, first unsuccessfully, and at 

 last successfully, was to discover the 

 circumstance in which all the ob- 

 served positions of the planet agreed. 

 And when he in like manner con- 

 nected another set of observed facts, 

 the periodic times of the different 

 planets, by the proposition that the 

 squares of the times are proportional 

 to the cubes of the distances, what 

 he did was simply to ascertain the 

 property in which the periodic times 

 of all the different planets agreed. 



Since, therefore, all that is true and 

 to the purpose in Dr. Whe well's doc- 

 trine of Conceptions might be fully 

 expressed by the more familiar term 

 Hypothesis ; and since his Colliga- 



tion of Facts by means of appropriate 

 Conceptions is but the ordinary pro- 

 cess of finding by a comparison of 

 phenomena in what consists their 

 agreement or resemblance ; I would 

 willingly have confined myself to those 

 better understood expressions, and 

 persevered to the end in the same 

 abstinence which I have hitherto ob- 

 served from ideological discussions ; 

 considering the mechanism of our 

 thoughts to be a topic distinct from 

 and irrelevant to the principles and 

 rules by which the trustworthiness of 

 the results of thinking is to be esti- 

 mated. Since, however, a work of such 

 high pretensions, and, it must also be 

 said, of so much real merit, has rested 

 the whole theory of Induction upon 

 such ideological considerations, it 

 seems necessary for others who fol- 

 low to claim for themselves and 

 their doctrines whatever position may 

 properly belong to them on the same 

 metaphysical ground. And this is the 

 object of the succeeding chapter. 



CHAPTER IL 



OF ABSTRACTION, OR THE FORMATION 

 OF CONCEPTIONS. 



§ I. The metaphysical inquiry into 

 the nature and composition of what 

 have been called Abstract Ideas, or, 

 in other words, of the notions which 

 answer in the mind to classes and to 

 general names, belongs not to Logic, 

 but to a different science, and our 

 purpose does not require that we 

 should enter upon it here. We are 

 only concerned with the universally 

 acknowledged fact that such notions 

 or conceptions do exist. The mind 

 can conceive a multitude of individual 

 -things as one assemblage or class ; and 

 general names do really suggest to us 

 certain ideas or mental representa- 

 tions, otherwise we coixld not use the 

 names with consciousness of a mean- 

 ing. Whether the idea called up by 

 a general name is composed of the 

 various circumstances in which all 



