VOL. XXI.] PHILOSOPHICAL TRANSACTIONS. 441 



of them n; there will be nothing wanting to an absolute certitude, against the 

 not failina; in the article or articles n, but only . 



** ' •'m+nxa + c 



Pkop. IV. — Concerning the truth of either Oral or IFritlen Tradition, in 

 whole or in part, successively transmitted, and also coattested by several Successions 

 ofTransmiltents. — 1. Supposing the transmission of an oral and narrative to be 

 so performed by a succession of single men, or joined in companies, as that each 

 transmission after the narrative has been kept for 20 years, impairs the credit of 

 it a 12th part; and that consequently at the 12th hand, or at the end of 240 

 years, its certainty is reduced to a half; and there grows then an even lay (by 

 the corollary of the second Prop.) against the truth of the relation : yet if we 

 further suppose, that the same relation is coattested by y other several suc- 

 cessions, transmitting alike each of them, the credibility of it, when they are 

 all found to agree, will (by the corollary of the first Prop.) be as i-§-H- of cer- 

 tainty, or above 1000 to 1 ; and if we suppose a coattestation of ig, the 

 credibility of it will be above two millions to one. 



2. In oral tradition, as a single man is subject to much casualty, so a com- 

 pany of men cannot be so easily supposed to join ; and therefore the credibility 

 of .i-|-»ths, or about 4^ths, may possibly be judged too high a degree for an 

 oral conveyance, to the distance of 20 years. But in written tradition, the 

 chances against the truth or conservation of a single writing are far less ; and 

 several copies may also be easily supposed to concur: and those since the in- 

 vention of printing exactly the same : also several distinct successions of such 

 copies may be as well supposed, taken by different hands, and preserved in 

 different places or languages. And therefore, if oral tradition by any one man, 

 or company of men, might be supposed to be credible after 20 years, at i| ths 

 of certainty; or but -j\ths of -|-ths ; a written tradition may be well imagined 

 to continue, by the joint copies that may be taken of it from one place, (like the 

 several copies of the same impression,) during the space of 100, if not 200 years ; 

 and to be then credible at J-g-fths of certainty, or at the proportion of 100 to 1. 

 And then seeing that the successive transmissions of this -ffi^ of certainty, will 

 not diminish it to half, until it passes the 69th hand, (for it will be near 70 

 years before the rebate of money, at that interest, will sink it to half.) It is 

 plain that written tradition if preserved but by a single succession of copies, will 

 not lose half of its full certainty, until 70 times 100, if not 70 times 200 years 

 are past; that is 7OOO, if not 14000 years; and further, that if it be likewise 

 preserved by concurrent successions of such copies, its credibility at that distance 

 may be even increased, and grow far more certain from the several agreeing de- 



voL. IV. 3 L 



