8 ESSAY ON PROBABILITIES. 



depends upon the constitution of the minds of B and C 

 what shall be the result of discussion upon them. Let 

 it be granted that the intellectual constitution of A, B, 

 and C is precisely the same at a given moment, and 

 there is ground for declaring that any difference of 

 opinion upon the same arguments must be one of moral 

 character. Granting, then, that it were quite certain A is 

 right, he might be justified in using methods with B 

 and C which are reformative of moral character ; that 

 is to say, granting that state punishments are reform- 

 ative of immoral habits, as well as repressive of im- 

 moral acts, he would be justified in direct persecution. 

 But to any one who is able to see with the eyes of his 

 body that the same weight will stretch different strings 

 differently, and with those of his mind that the same 

 arguments will affect different minds differently by 

 difference not of moral but of intellectual construction 

 will also see that the only legitimate process of alteration 

 is that of the latter character, not of the former ; 

 namely, argument * and discussion. In the mean time, 

 we bring it forward as not the least of the advantages 

 of this study, that it has a tendency constantly to keep 

 before the mind considerations necessarily corrective of 

 one of the most fearful taints of our intellect. 



Let us now consider what is the measure of proba- 

 bility. Any one thing is said to measure another when 

 the former grows with the growth of the latter, and 

 diminishes with its diminution. For instance, in the 

 tube of a thermometer, the height of the mercury above 

 freezing point (a line) measures the content of a cy- 

 linder ; not that a line is a solid, but twice as much 

 length belongs to twice as much content, and so on. 

 Again, the content of the cylinder measures the quantity 

 of expansion in a given quantity of mercury (and in 

 this case not only measures, but is). Thirdly, the 



* It is frequently asserted, that opinions dangerous to the existence of 

 public order must not be promulgated. This is a question distinct from the 

 one in the text, so far as it is political. If we grant no morals except expe- 

 diency, (which, it appears to us, is necessary for the affirmation of the pre- 

 ceding,) the answer is, simply, that persecution is ineffective. 



