A FRAGMENT ON TRUTH 267 



II. 



When it is said that by scientific measurement things, not 

 sensations, are compared, the word things must be interpreted 

 as bearing a very wide meaning. Time, space, matter, energy, 

 are included in the term. Measurements compare such things 

 as position, velocity, tenacity, and so forth. Call these attributes, 

 properties, abstractions, relations, conditions, actions, what you 

 will, the fact remains that when the man of science measures 

 these things, he compares the things themselves, not the sen- 

 sations they produce in his mind. Neither the method nor the 

 result of the comparison is affected by the individual mind, 

 except so far as concerns the more or less complete accuracy of 

 the measurement. 



No doubt one individual will weigh with less error than an- 

 other while using the same apparatus, and then the imperfec- 

 tion of our organs prevents absolute agreement about even 

 measurable things ; but the disagreement in these cases affects 

 the mere fringe or margin of the thing, not the thing in bulk. 

 One man comparing the weight of two masses, A and B, shall say 

 that A is twice as heavy as B ; another man shall say that this 

 relation is really 2 to I'OOOl ; but no person can be found to 

 measure so badly as to suppose that B is twice as heavy as A. 

 A reversal of this kind, or indeed any wide disagreement between 

 ,the measurements of fairly skilled observers is inconceivable, and 

 all the measurers act successfully on the supposition that there is 

 one real relation between the weights, and that this relation is 

 independent of the peculiarities of their own minds. Those fields 

 of knowledge in which this manner of comparison between the 

 things themselves is possible cover the domain of exact know- 

 ledge rightly so called, although we may never hope for absolute 

 exactitude in any measurement whatever. We know absolutely 

 that in those fields relations exist and that our senses enable us 

 to determine those relations with all the nicety which our wants 

 require. In these regions dispute is settled by an appeal to 

 things, not to minds ; no criterion of truth is missed, and pro- 

 longed difference of opinion concerning the relations measured is 



