Oi CRAIG. 



The paradox is made by Roberts himself, by his own arbitrary 

 definition of odds. 



Supposing a lottery has a blanks and h prizes, and let each 

 prize be r shillings ; and suppose a gamester gives a shilling for 

 one drawing in the lottery; then Roberts says the odds against 



a 1 



him are formed by the product of j ^^^ T > ^^^^ '^^) "tl^® ^^^^ 



are as a to Z> (r — 1). This is entirely arbitrary. 



The mere algebra of the paper is quite correct, and is a curious 

 specimen of the mode of work of the day. 



The author is doubtless the same whose name is spelt Robartes 

 in De Moivre's Preface. 



90. I borrow from Lubbock and Drinkwater an account of a 

 work which I have not seen ; it is given on their page 45. 



It is not necessary to do more than mention an essay, by Craig, on 

 the probability of testimony, which appeared in 1699, under the title 

 of "Theologi£e Cliristianse Principia Mathematica." This attempt to 

 introduce mathematical language and reasoning into moral subjects can 

 scarcely be read with seriousness ; it has the appearance of an insane 

 parody of Newton's Principia, which then engrossed the attention of the 

 mathematical world. The author begins by stating that he considers 

 the mind as a movable, and arguments as so many moving forces, by 

 which a certain velocity of suspicion is produced, &c. He proves 

 gravely, that suspicions of any history, transmitted through the given 

 time (cceteris ^9aH62^s), vary in the duplicate ratio of the times taken 

 from the beginning of the history, with much more of the same kind 

 with respect to the estimation of equable pleasure, uniformly accele- 

 rated pleasure, pleasure varying as any power of the time, &c. &c. 



It is stated in biographical dictionaries that Craig's work was 

 reprinted at Leipsic in 1755, with a refutation by J. Daniel Titius ; 

 and that some Anwiadversiones on it were published by Peterson 

 in 1701. 



Prevost and Lhuilier notice Craig's work in a memoir published 

 in the Memoires de VAcad... .Beiiin, 1797. It seems that Craig con- 

 cluded that faith in the Gospel so far as it depended on oral tra- 

 dition expired about the year 800, and that so far as it depended 

 on written tradition it would expire in the year 3150. Peterson 



