BOOK IV. 



OF OPERATIONS SUBSIDIARY 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 possibly it is 

 but here and there one who gives himself the trouble to consider them so far as to know what 

 he himself or others precisely mean by them ; I have, therefore, in most places, chose to put 

 detei-minate or determined, instead of clear and distinct, as more likely to direct men's thoughts 

 to my meaning in this matter." — Locke's Essay on the Human Understanding; Epistle to 

 the Keader. 



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

 ainsi un arrangement dans lequel les etres du meme genre seraient plus voisins entre eux que 

 ceux de tous les autres genres ; les genres du meme ordre, plus que ceux de tous 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 ['expression exacte et complete de la na- 

 ture entiere." — Cuviee, Regne Animal, Introduction. 



"Deux grandes notions philosophiques dominent la theorie fondamentale de la methode 

 naturelle proprement dite, savoir la formation des groupes naturels, et ensuite leur succession 

 hierarchique. " — Comte, Cours de Philosophie Positive, 42me le9on. 



CHAPTER I. 



OP OBSERVATION AND DESCRIPTION". 



§ 1. The inquiry which occuiaied us in the two preceding Books, has 

 conducted us to what appears a satisfactory solution of the principal prob- 

 lem of Logic, according to the conception I have formed of the science. 

 We have found, that the mental process 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 particularized the various 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 on. 



The consideration of Induction, however, does not end with the direct 

 rules for its performance. Something must be said of those other opera- 

 tions of the mind, which are either necessarily presupposed in ajl induction, 

 or are instrumental to the more difficult and complicated inductive process- 

 es. The present Book will be devoted to the consideration of these sub- 

 sidiary operations ; among which our attention must first be given to those, 

 which are indispensable preliminaiies to all induction whatsoever. 



Induction being merely the extension 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 operations subsidiary to induction, is 

 claimed by Observation. This is not, however, the place to lay down rules 

 for making good observers ; nor is it within the competence of Logic to do 

 so, but of the art of intellectual Education. Our business with observation 



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