[ 406 ] 
enquiry to be what reafon we fhall have to think we 
are right if we guefs that the probability of it’s hap- 
pening in a fingle trial lies fomewhere between -I®. 
and A, or that the ratio of the caufes of it’s happen- 
ing to thofe of it’s failure is fome ratio between that 
of fixteen to one and two to one. 
Here p + i = 1 1 , X — II and * = £ and X 
— — 't' 11 = .5013 See. The anfwer 
therefore is, that we fhall have very nearly an equal 
chance for being right. 
In this manner we may determine in any cafe what 
conclufion we ought to draw from a given number 
of experiments which are unoppofed by contrary 
experiments. Every one fees in general that there is 
reafon to expedt an event with more or lefs confidence 
according to the greater or lefs number of times in 
which, under given circumftances, it has happened 
without failing ; but we here fee exactly what this 
reafon is, on what principles it is founded, and how 
we ought to regulate our expeditions. 
But it will be proper to dwell longer on this 
head. 
Suppofe a folid or die of whofe number of fides 
and conftitution we know nothing ; and that we are 
to judge of thefe from experiments made in 
throwing it. 
In this cafe, it fhould be obferved, that it would 
be in the highefl degree improbable that the folid 
fhould, in the fir ft trial, turn anyone fide which could 
be affigned before hand ; becaufe it would be known 
that fome fide it mud turn, and that there was an in- 
finity of other fides, or fides otherwife marked, which 
it was equally likely that it fhould turn. The fit ft 
4 throw 
