FUNCTIONS AND VALUE OF THE SYLLOGISM. 149 



ence a general one. If, from observation and experiment, we can conclude 

 to one new case, so may we to an indefinite number. If that which has 

 held true in our past experience will therefore hold in time to come, it will 

 hold not merely in some individual case, but in all cases of some given 

 description. Every induction, therefore, which suffices to prove one fact, 

 proves an indefinite multitude of facts : the experience which justifies a sin- 

 gle prediction must be such as will suffice to bear out a general theorem. 

 This theorem it is extremely important to ascertain and declare, in its 

 broadest form of generality ; and thus to place before our minds, in its full 

 extent, the whole of what our evidence must prove if it proves any thing. 



This throwing of the whole body of possible inferences from a given set 

 of particulars, into one general expression, operates as a security for their 

 being just inferences, in more ways than one. First, the general principle 

 presents a larger object to the imagination than any of the singular prop- 

 ositions which it contains. A process of thought which leads to a com- 

 prehensive generality, is felt as of greater importance than one which ter- 

 minates in an insulated fact ; and the mind is, even unconsciously, led to 

 bestow greater attention upon the process, and to weigh more carefully 

 the sufficiency of the experience appealed to, for supporting the inference 

 grounded upon it. There is another, and a more important, advantage. 

 In' reasoning from a course of individual observations to some nefv and un- 

 observed case, which we are but imperfectly acquainted with (or we should 

 not be inquiring into it), and in which, since we are inquiring into it, we 

 probably feel a peculiar interest ; there is very little to prevent us from 

 giving way to negligence, or to any bias which may affect our wishes or 

 our imagination, and, under that influence, accepting insufficient evidence 

 as sufficient. But if, instead of concluding straight to the particular case, 

 we place before ourselves an entire class of facts — the whole contents of a 

 general proposition, every tittle of which is legitimately inferable from our 

 premises, if that one particular conclusion is so ; there is then a considera- 

 ble likelihood that if the premises are insufficient, and the general inference 

 therefore, groundless, it will comprise Avithin it some fact or facts the re- 

 verse of which we already know to be true; and we shall thus discover 

 the error in our generalization by a reductio ad impossihile. 



Thus if, during the reign of Marcus Aui-elius, a subject of the Roman 

 empire, under the bias naturally given to the imagination and expectations 

 by the lives and characters of the Antonines, had been disposed to expect 

 that Commodus would be a just ruler; supposing him to stop there, he 

 might only have been undeceived by sad experience. But if he reflected 

 that this expectation could not be justifiable unless from the same evidence 

 he was warranted in concluding some general proposition, as, for instance, 

 that all Roman emperors are just rulers; he would immediately have 

 thought of Nero, Domitian, and other instances, which, showing the falsity 

 yi the general conclusion, and therefore the insufficiency of the premises, 

 vvould have warned him that those premises could not prove in the instance 

 )f Commodus, what they were inadequate to prove in any collection of 

 ;ases in which his was included. 



The advantage, in judging whether any controverted inference is legiti- 

 nate, of I'eferring to a parallel case, is universally acknowledged. But by 

 iscending to the general proposition, we bring under our view not one par- 

 illel case only, but all possible parallel cases at once ; all cases to which the 

 ame set of evidentiary considerations are applicable. 

 When, thei'efore, we argue from a number of known cases to another case 



