400 ACTUAL WORKING IN ORIGINAL RESEARCH. 



CHAPTER XLV. 



USE OF GENERALISATION. 



Generalisation is the act of comprehending under a common 

 name several objects agreeing in some point which we abstract 

 from each of them, and which that common name serves to 

 indicate. WHATELEY. 



THE objects or phenomena which we compare for the 

 purposes of generalisation, may either be of the most 

 certain and invariable character, liable to the fewest 

 exceptions, and dependent upon the smallest number of 

 conditions ; or they may be of the most uncertain and 

 variable kind, subject to frequent exceptions, and depen- 

 dent upon many conditions ; or they may be of all degrees 

 of certainty between these two extremes. The term general- 

 isation is most usually applied to comparison of the 

 former, and analogy to that of the latter ; and arguments 

 therefore which are based upon analogy only are much 

 less cogent and more uncertain than those which are based 

 upon general truths. "We employ generalisation in two 

 ways for the purpose of aiding scientific discovery ; 1st, 

 To draw general conclusions from adequate evidence ; and 

 2nd, To raise general questions or hypotheses for further 

 investigation. 



Generalisation consists in conceiving general ideas 

 respecting two or more instances. The general ideas 

 conceived may be divided into two kinds, viz., those which 

 are proved by the evidence, and those which are not. In 

 the first of these cases, generalisation consists in detecting 

 identities in two or more different facts or phenomena by 

 means of the faculties of observation and comparison ; and 



