Chap. 14.] Analogical Rcafohing. 485 



as we are careful to note the proportions of thofe re- 

 fembling parts, and how far in each of the compared 

 ideas they may be connected with, and influenced by 

 others, it will generally prove a fafe method of reafon- 

 ing; but as the affociations are not near fo ftrong in 

 this relation, as in that of caufe and effect, as the rela- 

 tion is more complex and more removed from com- 

 mon experience, this mode of reafoning will more fre- 

 quently deceive us. Thus, " if we argue from the ufe 

 and action of the ilomach in one animal to thofe in 

 another, fuppofed to be unknown, there will be a pro- 

 bable hazard of being miftaken, proportional in ge- 

 neral to the known difference of the two animals, as 

 well as a probable evidence for the truth of part, at 

 lead, of what is advanced, proportional to the general 

 refemblance of the two animals ; but if, on examina- 

 tion, the ftomach, way of feeding, &c. of the fecond 

 animal fhould be found, to fenfe, the fame as in the 

 firft, the analogy might be confidered as an induction, 

 properly fo called, at leaft as approaching to it *." 



Reafoning may likewife be defective and falfe, from 

 accepting an axiom or conclufion drawn from a for- 

 mer judgment as an intuitive principle, or from an im- 

 perfect or partial view of the fubject, and from what 

 has been faid of cuftom, it is evident that it may. have a 

 great influence over our reafoning. Since ideas by re- 



* '* It is often in our power to obtain an analogy where we 

 cannot have an indudion, in which cafe reafoning from analogy 

 ought to be admitted ; however, with all that uncertainty which 

 properly belongs to it." Hartley on Man, Prop. 39. 



" The analogous natures of all the things about us are a great 

 afliftance in decyphering their properties, powers, laws, &c. inaf- 

 much as what is minute or obfcure in one may be explained and 

 illuftratod by the analogous particular in another, where it is large 

 and clear ; and thus all things become comments on each other in 

 in endlefs reciprocation." Hartley, Prop. 39. 



I i 3 petition 



