172 THE SCIENCE OF LOGIC 



Welton l in a section which he concludes with these words : &quot; Even such 

 an imperfect outline as the above makes abundantly manifest that induction 

 is by no means an easy process, or one that can be reduced to mechanical 

 rules ; that the procedure starts from and is guided throughout by hypotheses ; 

 that number of experiments is appealed to only as a guarantee that only known 

 conditions are operative ; that the procedure of perceptual analysis is to estab 

 lish a positive connexion, to purge this of exceptions and to limit and corro 

 borate it by negative instances ; and that one inductive enquiry gives rise to 

 others.&quot; 2 



Many valuable and instructive examples will also be found in Mr. Joseph s 

 Introduction to Logic, especially in chapter xx., 3 where the author sets forth 

 a number to illustrate &quot; the truth of the contention that inductive conclusions 

 are established disjunctively by the disproof of alternatives &quot;. 4 We have 

 already set forth this theory of the inductive process (212), and it now remains 

 to examine briefly the &quot;experimental methods,&quot; or rules according to which 

 this process of eliminating alternatives may be conducted. 



241. THE &quot; RULES &quot; OR &quot; CANONS &quot; OF INDUCTIVE ANALY 

 SIS; &quot;METHODS&quot; OF &quot;AGREEMENT&quot; AND &quot;DIFFERENCE&quot;. By 

 a study of the various plans of procedure actually adopted by 

 scientists in inductive research, logicians have been able to formu 

 late certain practical rules or canons of which an explicit knowledge 

 cannot fail to prove useful towards the discovery and proof of 

 causal laws. 



Lord Bacon s tabulae praesentiae, tabulae absentiae, and tabulae 

 comparativae? represent a somewhat crude attempt at such formu 

 lation. Sir John Herschel s Preliminary Discourse on the Study 

 of Natural Philosophy marks an important step in the logical 

 analysis of scientific procedure, and it was from this work that 

 John Stuart Mill avowedly drew the four (or five) &quot; methods &quot; 

 that have been ever since inseparably associated with the latter s 

 name. 6 Mill s formulation of them, however, is somewhat clumsy, 

 and is, besides, in many ways defective ; and, while altogether 

 overrating their value, he in part misunderstood their real scope 

 and significance. Those mistakes of his have been corrected by 

 subsequent logicians. 7 Most of what these rules contain is implied 

 in what has been said in the previous section (240) concerning 

 analysis and experiment ; but what was there briefly outlined will 

 be better understood by formulating and illustrating the various 



1 op. cit. ii., pp. 122-41. &quot;*ibid., pp. 140-1. Cf. infra, 245. 



3 Cf. also chaps, xxii. and xxvi. 4 p. 408. 



*Novum Organum, ii. passim, Cf. ADAM, La philosophic de Frangois Bacon 

 (Paris, 1890). 



6 Cf, Inductive Logic, III., viii. and ix. ; JOSEPH, op. cit., p. 397, n. 2. 



Cf., for instance, the text-books ot WELTON, MELLONE and JOSEPH ; also Mr. 

 LAURIE S articles in Mind (N.S., vol. ii., 1893). 



