SECT. 11.] Testimony. 405 



the actual majority is the same. That is, the unanimous 

 judgment of a jury of eight is to count for the same as a 

 majority of ten to two in a jury of twelve. And yet this 

 conclusion is admitted by Poisson. The assumptions under 

 which it follows will be indicated in the course of the next 

 chapter. 



Again, perfect independence amongst the witnesses or 

 jurors is an almost necessary postulate. But where can this 

 be secured ? To say nothing of direct collusion, human 

 beings are in almost all instances greatly under the influence 

 of sympathy in forming their opinions. This influence, under 

 the various names of political bias, class prejudice, local 

 feeling, and so on. always exists to a sufficient degree to 

 induce a cautious person to make many of those individual 

 corrections which we saw to be necessary when we were 

 estimating the trustworthiness, in any given case, of a single 

 witness ; that is, they are sufficient to destroy much, if not 

 all, of the confidence with which we resort to statistics and 

 averages in forming our judgment. Since then this Essay is 

 mainly devoted to explaining and establishing the general 

 principles of the science of Probability, we may very fairly 

 be excused from any further treatment of this subject, beyond 

 the brief discussions which are given in the next chapter. 



