 The date which historians cite as the beginning of the development of modern probability theory is 1654 , when two of the most well @-@ known mathematicians of the time , Blaise Pascal and Pierre de Fermat , began a correspondence discussing the subject . The two initiated the communication because earlier that year , a gambler from Paris named Antoine <unk> had sent Pascal and other mathematicians several questions on the practical applications of some of these theories ; in particular he posed the problem of points , concerning a theoretical two @-@ player game in which a prize must be divided between the players due to external circumstances halting the game . The fruits of Pascal and Fermat 's correspondence interested other mathematicians , including Christiaan Huygens , whose De <unk> in aleae ludo ( Calculations in Games of Chance ) appeared in 1657 as the final chapter of Van <unk> 's <unk> <unk> . In 1665 Pascal posthumously published his results on the eponymous Pascal 's triangle , an important combinatorial concept . He referred to the triangle in his work Traité du triangle <unk> ( Traits of the Arithmetic Triangle ) as the " arithmetic triangle " . 
