CHAP. XVI.] OF THE THEORY OF PROBABILITIES. 243 



CHAPTER XVI. 



ON THE THEORY OF PROBABILITIES. 



1. T3EFORE the expiration of another year just two centuries 

 -"-^ will have rolled away since Pascal solved the first known 

 question in the theory of Probabilities, and laid, in its solution, 

 the foundations of a science possessing no common share of the 

 attraction which belongs to the more abstract of mathematical 

 speculations. The problem which the Chevalier de Mere, a re- 

 puted gamester, proposed to the recluse of Port Royal (not yet 

 withdrawn from the interests* of science* by the more distracting 

 contemplation of the "greatness and the misery of man"), was 

 the first of a long series of problems, destined to call into exis- 

 tence new methods in mathematical analysis, and to render va- 

 luable service in the practical concerns of life. Nor does the in- 

 terest of the subject centre merely in its mathematical connexion, 

 or its associations of utility. The attention is repaid which is 

 devoted to the theory of Probabilities as an independent object 

 of speculation, to the fundamental modes in which it has been 

 conceived, to the great secondary principles which, as in the 

 contemporaneous science of Mechanics, have gradually been an- 

 nexed to it, and, lastly, to the estimate of the measure of per- 

 fection which has been actually attained. I speak here of that 

 perfection which consists in unity of conception and harmony of 

 processes. Some of these points it is designed very briefly to 

 consider in the present chapter. 



2. A distinguished writerj has thus stated the fundamental 

 definitions of the science : 



* See in particular a letter addressed by Pascal to Fermat, who had solicited 

 his attention to a mathematical problem (Port Royal, par M. de Sainte Beuve); 

 also various passages in the collection of Fragments published by M. Prosper 

 Faugere. 



f Poisson, Recherches sur la Probabilite des Jugemens. 



R2 



