SCIENTIFIC METHOD 51 



on the forehead they appear to be of different weight, 

 although we know them to be equal. These examples, 

 out of many which might be cited, will be sufficient to 

 show the fallibility of the senses. It is clear that we can 

 only trust the evidence of sensation with great reserve, 

 and it is, therefore, not surprising that the conclusions 

 reached by the scientific method with its appeal to 

 reason should, in many cases, be opposed to those 

 derived from unsifted sensory impressions. There is 

 in consequence a real basis for the conflict between 

 scientific deductions and common-sense judgements, 

 since the latter are largely the general opinion based 

 on sensory perceptions, and accepted without that correc- 

 tion which mature reflection affords. As Glanville says, 

 'opinions are the rattles of immature intellects, but the 

 advanced reasons have outgrown them.' 



Imagination as an aspect of the scientific method. 



I have reserved to the last this aspect of my subject ; 

 it is in many respects, and particularly in this age, the 

 most interesting of all. The scientific method has been 

 adversely criticized because, not content with observa- 

 tions and experiments on natural phenomena and with 

 deducing from these a scheme of causative sequence, 

 based on the authority of reason, it leaps beyond the 

 domain of pure reason and enters that of the imagination. 

 To those who have never read it let me commend such 

 lectures as that 'On the scientific use of the imagination', 

 delivered by Tyndall before the British Association in 

 1 870*. I will quote a few scattered passages from this 

 and other essays to give you a foretaste of their quality. 



' Philosophers may be right in affirming that we cannot 



1 Tyndall, Fragments of Science^ vol. ii. 

 E 2 



