SCIENTIFIC TRUTH IS SELF-CONSISTENT. 157 



our experiences, when corrected by the powers of the 

 intellect, unite to prove that the intellect in general, and 

 the reasoning faculty in particular, are the means "by 

 which alone, acting upon the evidence supplied by the 

 other powers, we are enabled to distinguish truth. To 

 make this clear; we know that all our mental posses- 

 sions consist of ideas, and that ideas may be either true 

 or false. In discriminating the truthful ones we employ 

 the intellect, including the powers of perception, attention, 

 comparison, reason, and judgment. Thus we, 1st, perceive 

 the ideas ; 2nd, direct attention to them ; 3rd, compare 

 them with other ideas which we know are most certain to 

 be true, such as the great principles of nature, including 

 those of non-contradiction, causation, conservation and 

 equivalency of energy, action and reaction, inertia and 

 momentum, &c., and ascertain if they are similar in their 

 essential attributes ; 4th, we conclude by an act of infer- 

 ence that they are therefore true ; and 5th, by an act of 

 judgment we decide upon them. 



As this explanation seems fully to account for the 

 effect, and it is clear that the will (which is only a con- 

 scious mental effort to effect an object, the idea of which 

 is already in the mind) cannot select ideas ; it is unneces- 

 sary either to assume that we possess a special or occult 

 power of discerning truth, such as a 6 moral sense ;' or 

 to prove that each of our other powers, not included in 

 the intellect (such as the feelings), are blind, and cannot 

 compare or reason, and therefore cannot distinguish, or 

 really select, ideas, although they appear to do so. We 

 possess no royal or infallible mode of instantly selecting 

 truthful ideas, not even by means of the intellect ; and the 

 labour of distinguishing truth is the work of all mankind 

 through all time, and supplies the discipline which de- 

 velops our intellectual and moral faculties. 



