38 



GENERAL PREFACE TO 







This omission is doubtless connected with the kind of 

 realism which runs through Bacon's system, and which renders 

 it practically useless. For that his method is impracticable 

 cannot I think be denied, if we reflect not only that it never 

 has produced any result, but also that the process by which 

 scientific truths have been established cannot be so presented as 

 even to appear to be in accordance with it. In all cases this 

 process involves an element to which nothing corresponds in 

 the tables of comparence and exclusion ; namely the application 

 to the facts of observation of a principle of arrangement, an idea, 

 existing in the mind of the discoverer antecedently to the act of 

 induction. It may be said that this idea is precisely one of the 

 naturae into which the facts of observation ought in Bacon's 

 system to be analysed. And this is in one sense true ; but it 

 must be added that this analysis, if it be thought right so to call 

 it, is of the essence of the discovery which results from it. To 

 take for granted that it has already been effected is simply a 

 petitio principii. In most cases the mere act of induction 

 follows as a matter of course as soon as the appropriate idea has 

 been introduced^ If, for instance, we resolve Kepler's disco- 

 very that Mars moves in an ellipse into its constituent elements, 

 we perceive that the whole difficulty is antecedent to the act 

 of induction. It consists in bringing the idea of motion in an 

 ellipse into connexion with the facts of observation ; that is, in 

 showing that an ellipse may be drawn through all the observed 

 places of the planet. The mere act of induction, the sTraycoytj, 

 is perfectly obvious. If all the observed places lie on an ellipse 

 of which the sun is the focus, then every position which the 

 planet successively occupies does so too. This inference, which 

 is so obvious that it must have passed through the mind of the 

 discoverer almost unconsciously, is an instance of induction 

 "per enumerationem simplicem;" of which kind of induction 

 Bacon, as we have seen, has said that it is utterly vicious and 

 incompetent. 



The word realism may perhaps require some explanation. 

 I mean by it the opinion, which Bacon undoubtedly entertained, 

 that for the purposes of investigation, the objects of our thoughts 

 may be regarded as an assemblage of abstract conceptions, so 

 that these conceptions not only correspond to realities, which is 

 of course necessary in order to their having any value, but may 

 also be said adequately to represent them. In his view of the 



