BOOK IV. 



OF OPERATIONS SUBSIDIAEF TO 

 INDUCTION. 



" Clear and distinct ideas are terms which, though familiar and frequent in men's 

 mouths, I have reason to think every one who uses does not perfectly understand. And 

 lX)S8ibly it is but here and there one who gives himself the trouble to consider them 

 so far as to know wliat he himself or others precisely mean by them ; I have, therefore, 

 in most places, chose to put determinate or determined, instead of clear and distinct, 

 as more likely to direct men's thoughts to my meaning in this matter."— Locke's Eaatj 

 OH the llamun Understanding ; Epistle to the Reader. 



" II ne pent y avoir qu'une methode parfaite, qui est la mithode naturelU: on nomme 

 ainsi uu arrangement dans lequel les etres du mSme genre seraient plus voisins eutro 

 eux que ceux de tous les autres genres ; les genres du mome ordrc, plus que ceux de tons 

 les autres ordres ; et ainsi de suite. Cette methode est I'ideal auquel I'histoire naturelle 

 doit tendre ; car il est Evident que si Ton y parvenait, Ton aurait I'expressiou cxacte ct 

 complete de la nature entiferc."— Cvvier, Jiegtit Animal, Introduction. 



"Deux gi-andes notions philosophiques dominent la thdorie fondamentale de la 

 Tuethode naturelle proprement ditc, savoir la formation des groupes naturels, et ensuite 

 leur succession hierarchique."— Comte, Cours de Philosophie Positive, 42me leQon. 



CHAPTER I. 



OP OBSERVATION AND DESCRIPTION. 



§ I. The inquiry which occupied 

 T19 in the two preceding books has 

 conducted us to what appears a satis- 

 factory solution of the principal pro- 

 blem of Logic, according to the con- 

 ception I have formed of the science. 

 We have found that the mental pro- 

 cess with which Logic is conversant, 

 the operation of ascertaining truths 

 by means of evidence, is always, even 

 when appearances point to a different 

 theory of it, a process of induction. 

 And we have particularised the vari- 

 ous modes of induction, and obtained 

 a clear view of the principles to which 

 it must conform, in order to lead to 

 results which can be relied oo- 



The consideration of Induction, 

 however, does not end with the direct 

 rules for its performance. Something 

 must be said of those other operations 

 of the mind, which are either neces- 

 sarily presupposed in all induction, 

 or are instrumental to the more diffi- 

 cult and complicated inductive pro- 

 cesses. The present book will be de- 

 voted to the consideration of these 

 subsidiary operations, among which 

 our attention must first be given to 

 those which are indispensable pre- 

 liminaries to all induction whatso- 

 ever. 



Induction being merely the exten- 

 sion to a class of cases of something 

 which has been observed to be true in 

 certain individual instances of the 

 class, the first place among the opej-j^- 



