APPROXIMATE GENERALIZATIONS. 355 



of being Jeduced from the known cause, or from the known criterion, 

 of B. Let the question, for example, be, Whether most Scotchmen 

 can read ? We may not have observed, or received the testimony of 

 others respecting, a sufficient luimber and variety of Scotchmen to 

 ascertain this tact ; but when we consider that the cause of being able 

 to read is the having been taught it, another mode of determining the 

 question presents itself, namely, by inquiring whether most Scotchmen 

 have been sent to schools where reading is effectually taught. Of 

 these two modes, sometimes one and sometimes the other is the more 

 available. In some cases, the frequency of the effect is the more ac- 

 cessible to that extensive and varied observation which is indispensable 

 to the establishment of an empirical law; at other times, tlie freipiency 

 of the causes, or of some collateral indications. It commonly happens 

 that neither is susceptible of so satisfactory an induction as could be 

 desired, and that the grounds on which the conclusion is received are 

 compounded of both. Thus a man may believe that most Scotchmen 

 can read, because, so far as his information extends, most Scotch- 

 men have been seat to school, and most Scotch schools teach reading 

 effectually; and also because most of the Scotchmen whom he has 

 known or heard of, could read ; though neither of these two sets of 

 observations may by itself fulfill the necessary conditions of extent and 

 variety. 



Altliough the approximate generalization may in most cases be 

 indispensable for our guidance, even when we know the cause, or 

 some certain mark, of the attribute predicated; it needs hardly be 

 obsei-ved that we may always replace the uncertain indication by a 

 certain one, in any case in which we can actually recognize the ex- 

 istence of the cause or mark. For example, an assertion is made 

 by a witness, and the question is, whether to believe it. If we do not 

 look to any of the individual circumstances of the case, we have 

 nothing to direct us but the approximate generalization, that truth 

 is more common than falsehood, or, in other words, that most per- 

 sons, on most occasions, speak truth. But if we consider in what 

 circumstances the cases when truth is spoken differ from those in 

 which it is not, we find, for instance, the following: the witness's being 

 an honest man or not ; his being an accurate observer or not ; his 

 having an interest to serve in the matter or not. Now, not only may 

 we be able to obtain other approximate generalizations respecting the 

 degi'ee of frequency of these various possibilities, but we may know 

 which of them is positively realized in tlie individual case. That the 

 witness has or has not an interest to serve, we may know directly; 

 and the other two points indirectly, by means of marks ; as, for ex- 

 ample, fi'om his conduct on some former occasion ; or fi-om his rep- 

 utation, which, though not a sure mark, affords an a{)proximate 

 generalization (as, for instance. Most persons who are reputed honest 

 by those with whom they have had fi-equent dealings, arc really so,) 

 which approaches nearer to an universal truth than the ajiproximate 

 general proposition with which we set out, viz., Most persons on most 

 occasions speak truth. 



As it seems unnecessary to dwell any further upon the question of 

 the evidence of approximate generalizations, we shall proceed to a not 

 less important topic, that of the cautions to be observed in arguing 

 from these incompletely universal propositions to particular cases 



