CRITERIA OF SCIENTIFIC TRUTH. 153 



CHAPTEE XIII. 



ON THE CRITERIA OF SCIENTIFIC TRUTH. 



Truth, like a perfect picture, filled in every part, 

 Produces full conviction on every open heart. 



WHAT is truth ? and what are the complete criteria of 

 truth ? are questions which have occupied the minds of 

 men in all ages, and can probably be fully solved only by 

 means of perfect and infinite knowledge. 



Truth is universal consistency, unity in diversity ; all 

 truth is one by possessing these essential attributes. But 

 although all truth is consistent, consistency is not neces- 

 sarily truth, because there may be a limited consistency 

 of imaginary existences, or a self-consistent limited system 

 of error. Immediate consciousness also cannot be a cri- 

 terion of truth, because all our senses are apt to deceive 

 us and sometimes contradict each other; nor can our 

 intuitive mental tendencies, because they are very mis- 

 leading. 



According to Sir John Herschel, ' the grand and 

 indeed only character of truth is its capability of enduring 

 the test of universal experience, and coming unchanged 

 out of every possible form of fair discussion.' 1 According 

 to Archbishop Thomson, ' evidence is the sole means of 

 establishing, and therefore the sole standard for testing, 

 the truth of any proposition.' ' Four principal criteria 

 of truth have been in different forms advocated by 

 logicians, viz. : 



1 Discourse on Natural Philosophy ', p. 10. 



