tss 



REASONING. 



having been found true of those 

 known cases, we consider ourselves 

 warranted in holding true of any 

 other case resembling the former in 

 certain given particulars. 



If all ratiocinations resembled, as 

 to the minor premise, the examples 

 which were exclusively employed in 

 the preceding chapter ; if the resem- 

 blance, which that premise asserts, 

 were obvious to the senses, as in the 

 proposition " Socrates is a man," or 

 were at once ascertainable by direct 

 observation ; there would be no neces- 

 sity for trains of reasoning, and De- 

 ductive or Ratiocinative Sciences 

 would not exist. Trains of reasoning- 

 exist only for the sake of extending 

 an induction founded, as all induc- 

 tions must be, on observed cases, to 

 other cases in which we not only 

 cannot directly observe the fact which 

 is to be proved, but cannot directly 

 observe even the mark which is to 

 prove it. 



§ 2. Suppose the syllogism to be. 

 All cows ruminate ; the animal which 

 is before me is a cow ; therefore it 

 i-uminates. The minor, if true at all, 

 is obviously so : the only premise 

 the establishment of which requires 

 any anterior process of inquiry is the 

 major ; and provided the induction 

 of which that premise is the expres- 

 sion was correctly performed, the con- 

 clusion respecting the animal now 

 present will be instantly drawn ; 

 because, as soon as she is compared 

 with the formula, she will be identi- 

 fied as being included in it. But 

 suppose the syllogism to be the fol- 

 lowing : — All arsenic is poisonous, 

 the substance which is before me is 

 arsenic, therefore it is poisonous. 

 The truth of the minor may not here 

 be obvious at first sight ; it may not 

 be intuitively evident, but may itself 

 be known only by inference. It may 

 be theconclusion of another argument, 

 which, thrown into the syllogistic 

 form, would stand thus : — Whatever 

 when lighted prcxiuces a dark spot on 

 a piece of white porcelain held in the 



flame, which spot is soluble in hypo- 

 chloride of calcium, is arsenic ; the 

 substance before me conforms to this 

 condition ; therefore it is arsenic 

 To establish, therefore, the ultimate 

 conclusion, The substance before me 

 is poisonous, requires a process which, 

 in order to be syllogistically expressed, 

 stands in need of two syllogisms ; and 

 we have a Train of Reasoning. 



When, however, we thus add syl- 

 logism to syllogism, we are really 

 adding induction to induction. Two 

 separate inductions must have taken 

 place to render this chain of inference 

 possible ; inductions founded, pro- 

 bably, on different sets of individual 

 instances, but which converge in their 

 results, so that the instance which is 

 the subject of inquiry comes within 

 the range of them both. The record 

 of these inductions is contained in the 

 majors of the two syllogisms. First, 

 we, or others for us, have examined 

 various objects which yielded under 

 the given circumstances a dark spot 

 with the given property, and found 

 that they possessed the properties 

 connoted by the word arsenic ; they 

 were metallic, volatile, their vapour 

 had a smell of garlic, and so forth. 

 Next, we, or others for us, have exa- 

 mined various specimens which pos- 

 sessed this metallic and volatile cha- 

 racter, whose vapour had this smell, 

 &c., and have invariably found that 

 they were poisonous. The first obser- 

 vation we judge that we may extend 

 to all substances whatever which yield 

 that particular kind of dark spot ; 

 the second, to all metallic and vola- 

 tile substances resembling those we 

 examined ; and consequently, not to 

 those only which are seen to be such, 

 but to those which are concluded to 

 be such by the prior induction. The 

 substance before us is only seen to 

 come within one of these inductions ; 

 but by means of this one it is brought 

 within the other. We are still, as 

 before, concluding from particulars 

 to particulars ; but we are now con- 

 cluding from particulars observed, to 

 other particulars which are not, as in 



