114 GENERAL VIEW AND BASIS OF SCIENTIFIC RESEARCH 



the solution of it, because it is often preliminary to it an* 

 the condition of it. 



Mental confusion also leads to error, and in scientific 

 research is worse than error itself, because when we detect 

 ourselves in error, we have only to adopt the opposite 

 course or belief, or merely retrace our path, in order to 

 arrive either at truth or absence of error ; but when we 

 find ourselves confused or distracted, we do not know 

 which way to turn. 



Many errors are errors of data. We take for granted 

 that statements we have heard or read are true, without 

 first obtaining reasonable evidence that they are. so. 

 Another source of error, closely allied to this, is failing to 

 proportion the strength of our belief to the strength of the 

 evidence, by permitting hypotheses to become fixed con- 

 victions, and acting upon them as if they were proved 

 truths. As we have no unerring means of divining at 

 once the truth, and our ideas can neither be proved nor 

 disproved until the necessary knowledge is possessed, we 

 are compelled to entertain unproved and unprovable opi- 

 nions on many subjects, and to act upon them; but we 

 should always hold them with less fixity than verified 

 truths, lest they may be false. 



Many of our mistakes arise from errors of sense or 

 observation; the eye, for example, cannot accurately 

 determine degrees of absolute or even of relative bright- 

 ness, nor can the ear determine exactly different intensities 

 of sound. Similarly we are unable by the eye or by the 

 sense of feeling to detect slight differences of form, mag- 

 nitude, or distance ; colder bodies feel heavier, &c. ; and 

 all these statements are true, whether we employ aids to 

 our senses or not. Our observing powers also vary greatly 

 in accuracy with our physical state, but are always imper- 

 fect. Some of the impressions made on our consciousness 



