C 36 ] 



X. Note to the Rev. William Vernon Harcourt's 

 Letter to Lord Brougham. 



To Richard Taylor, Esq. 

 Dear Sir, 

 rTAVING in a contribution to the last volume of the Phi- 

 ■■■-*■ losophical Magazine touched on certain views of the 

 evidence of inductive philosophy, which I apprehend to be er- 

 roneous, I wish, with your permission, to explain in a some- 

 what fuller degree, though briefly, my own conceptions of the 

 real nature of that evidence ; and request you to subjoin these 

 explanations as a supplementary note, either in the Magazine 

 or in the separate publication, which you have been so kind 

 as to propose, of my account of the discovery of the gases 

 and of the composition of water. 



I remain, dear Sir, 



Yours faithfully, 

 Bolton Percy, June 15. W. Vernon Harcourt. 



The ideas which Mr. Macauley appears to entertain of in- 

 ductive and probable evidence*, as depending on the number 

 of instances, have obtained currency in some of our academical 

 schools, chiefly, I believe, from the authority of a great moral 

 and metaphysical writer, whose studies did not lie in the di- 

 rection of natural and experimental philosophy. "A low 

 presumption," says Bishop Butler, "often repeated, will 

 amount to a moral certainty. Thus a man's having observed 

 the ebb and flow of the tide today, affords some sort of pre- 

 sumption, though the lowest imaginable, that it may happen 

 again tomorrow : but the observation of this event for so 

 many days and months and ages together, as it has been ob- 

 served by mankind, gives us a full assurance that it willf." 



It is the greatest of Butler's merits, that on subjects of the 

 most abstruse and important speculation, formerly discussed 

 by a priori reasoning, he substituted the inductive for the hy- 

 pothetical method, and argued with just precaution and due 

 corrections from what is to what probably, or not improbably, 

 may be. "Into the nature," however, "the foundation and mea- 

 sure of probability, it is not my design," he adds, " to inquire 

 further; this belongs to the subject of logic, and is a part of that 

 subject which has not yet been fully considered." Nevertheless 

 since the soundness of all our practical judgements, and all our 

 intellectual conclusions depend on our understanding well the 

 grounds whereon they rest, it is of the utmost consequence to 



* See Phil. Mag., vol. xxviii. p. 513. 

 f Butler's Analogy, Introduction, p. 1. 



