1808.] 
‘pition; and it is remarkable that the au- 
thor should have disapproved of it, when 
he advances (page 221, r. 419) that the 
argument adduced by Berkeley against 
the substantiality of bodies are insoluble, 
that he has demonstrated that bodies are 
modes, and uot substances. 
The chief part of the first section is 
employed in covying from Berkeley and 
Burke passages to prove that words are 
understood even when they excite no 
precise idea. Had Dr. K. recollected 
Campbell’s Philosophy of Rhetoric, he 
might perhaps have favoured us with his 
way of accounting for this difficulty. If 
this had not satished him, Professor Stu- 
art, inhis Philosophy of the Human Mind, 
might have been quoted for an exempli- 
fication of the rapidity with which the 
mind passes from one idea to another. 
Page 98, r. 198.—An example is here 
given of compound propositions, ‘ All 
events are necessary, because they are 
foreseen.” 
IJere, says the author, the first branch, 
“ All events are necessary,” is false: in 
tlle second, the fact is true, but the 
cause is falsely assigned. 
Could alogician, whose reasoning pow- 
ers were not afiected by his religious pre- 
judices, deny the truth of the conclusion ? 
Page 137, r. 255.—‘ The presumed si- 
militude of future to ‘past events, often 
repeated, and of the past to the present, 
in similar circumstances,” is, according 
to the author, suggested by instinct. 
By instinct! Is there not here a mis- 
nomer? 
Page 252, r. 286-7-8-9.—Here are 
four distinctions, into which certainty is 
divided—metaphysical, physical, moral, 
and mixed, to which I see no objections: 
but in the preceding page (1. 285): it is 
said : 
“ Evidence is always accompanied 
with certainty, but certainty is often des- 
titute of evidence: thus some Mahome- 
tans are as certain of the truth of their 
religion as we are of ours.” 
Can it with propriety be said that. the 
Mahometans are certain of that of which 
they are supposed to form an erroneous 
opinion ? 
Page 260, r. 482.—The author dis- 
putes the possibility that the uckets of a 
lottery, consisting of 50,000 numbers, 
may be drawn in their numeral order, as 
1, 2, 3, 4, a supposition which he calls 
absurd. 
Now, as I cannot suppose it possible, 
that any human being should suppose it 
not possible that such an occurrence might 
' 
Remarks on Dr. Kirwan’s “ Logick.”’ 209 
possibly happen, I shall pass on. to the 
most extraordinary part of this perform- 
ance, which is the application of calcu- 
lation to probability, as applied to the 
truth of testimony. The author ob- 
serves, in his preface, that it has not 
been comprised in any treatise of logick, 
or that it has been but slightly noticed. 
Sir William Petty, he says, was the first 
who applied it to important objects; 
and Leibnitz, in the year 1669, applied 
it to political reasoning. 
After having at some length considered 
all the direct and mdirect proofs of pro- 
bability, we come to page 284, r. 534, 
which is, 
“Tf the probability that one man A, 
shall live a year, be 8, and the probabi- 
lity of the life of another man B. for one 
year be 3%, the probability that both 
shall live another year is 5x 4——705, 
which is remarkable; for thus we see 
that» the concurrence of two events is 
less probable than the occurrence of 
either; and is even improbable, though 
each is probable, and totally independent 
of the other”) > 
Pray, Dr. K. where is the wonder ? 
The application of calculation to tes- 
timony 1s founded on our knowledge or 
conjecture of the credibility of witnesses, 
and this is estimated by their possession 
of several qualifications, which he had 
before enumerated, and which he has re- 
duced to two, viz. integrity and know- 
ledge, and of the degrees in which those 
qualifications may be defective. The 
former constitute the chances favourable 
to their, credibility, and the latter the 
chances adverse to it. By a deficiency, 
all thatis wanting of any qualification to 
reach a certainty thatis, an unit is meant. 
Page 297, r. 557.—“ Let the know- 
ledge of the witness be denoted by k, 
and the deficiency k. Let. his integrity 
be denoted by I, and its deficiency by I, 
then his credibility will be expressed by 
epee | 
the fraction PReet 
I have called this method of estimating 
the credibility of witnesses extraordinary, 
and J flatter myself, Sir, that you will 
coincide with me in opmion, though a 
Leibnitz or a Halley should be against us. 
Tt is nothing less than to dive into the 
inmost recesses of the human mind. Be- 
fore the credibility of an evidence can 
be mathematically shewn, we must be 
able to calculate the force of looks and 
gestures, as wellas words. Where ts the ' 
criterion? Who is to measure the de. 
grees? The peraon who is to pronounce 
judgment 
