PREFACE. V 



obtained, is often involved by a confused apprehension 

 of the import of the different classes of Words and 

 Assertions, will not regard these discussions as either 

 frivolous, or irrelevant to the topics considered in the 

 later Books. 



On the subject of Induction, the task to be 

 performed was that of generalizing the modes of in- 

 vestigating truth and estimating evidence, by which 

 so many important and recondite laws of nature have, 

 in the various Sciences, been aggregated to the stock 

 of human knowledge. That this is not a task free 

 from difficulty may be presumed from the fact, that 

 even at a very recent period, eminent writers (among 

 whom it is sufficient to name Archbishop Whately, 

 and the author of a celebrated article on Bacon in 

 the Edinburgh Review,) have not scrupled to pronounce 

 it impossible. The author has endeavoured to combat 

 their theory in the manner in which Diogenes con- 

 futed the sceptical reasonings against the possibility 

 of motion; remembering that Diogenes' argument 

 would have been equally conclusive, although his 

 individual perambulations might not have extended 

 beyond the circuit of his own tub. 



Whatever may be the value of what the author has 

 succeeded in effecting on this branch of his subject, 

 it is a duty to acknowledge that for much of it 

 he has been indebted to several important trea- 

 tises, partly historical and partly philosophical, OP 

 the generalities and processes of physical science, 

 which have been published within the last few years. 

 To these treatises, and to their authors, he has endea- 



