142 GENERAL VIEW AND BASIS OF SCIENTIFIC RESEARCH. 



tain.' In the simplest sciences certainty exists in its 

 highest degree, but in complex and debateable cases our 

 certainty of the truth of a statement is vague, and often 

 largely mixed up with our feelings ; that which one man 

 feels and believes to be certain, another feels very doubtful 

 about. The region of ignorance and uncertainty is also 

 the region of faith and strife. 



Nothing calms the mind in a case of strife, so much, 

 as, first, to be convinced that there are determinate causes 

 for every event, and second, to know and appreciate what 

 are the causes, and the modes of their action. It is this 

 deep-rooted conviction of the universality of causation, and 

 a better understanding of the modes of operation of natural 

 power, which imparts to scientific men in general their 

 well-known characteristics of calmness and patience. A 

 feeling of certainty, however, and certainty itself are very 

 different ; the former may arise either from an erroneous 

 belief, or from one which has been well-founded upon true 

 and sufficient evidence; and it is therefore necessary to 

 distinguish between a mere feeling of certainty, and cer- 

 tainty itself; and between beliefs which are only ap- 

 parently true, and those which are really so. According 

 to Locke knowledge acquired by means of sensation is 

 less certain than that obtained by demonstration. 1 



Scientific knowledge impresses upon us every degree of 

 actual certainty according to the strength and amount 

 of evidence in support of the particular statement. The 

 chief basis and sign of real certainty is consistency with 

 nature. Science may conflict with dogma, but not with 

 truth in any subject whatever. Amongst the most actually 

 certain of scientific beliefs are the immediate results of the 

 simplest forms of logical proof, the axioms of Euclid, the 



1 Human Understanding, book iv. ch. xi. 



