SECT. 26.] Induction. 227 



not in any way contradictory, but they need some explana 

 tion. It will readily be seen that, taken together, they are 

 inconsistent with the supposition that each of these classes is 

 homogeneous, that is, that the statistical proportions which 

 hold of the whole of either of them will also hold of any 

 portion of them which we may take. There are certain 

 individuals (viz. the consumptive Englishmen) who belong 

 to each class, and of course the two different sets of statistics 

 cannot both be true of them taken by themselves. They 

 might coincide in their characteristics with either class, but 

 not with both ; probably in most practical cases they will 

 coincide with neither, but be of a somewhat intermediate 

 character. Now when it is said of any such heterogeneous 

 body that, say, nine-tenths die, what is meant (or rather 

 implied) is that the class might be broken up into smaller 

 subdivisions of a more homogeneous character, in some of 

 which, of course, more than nine-tenths die, whilst in others 

 less, the differences depending upon their character, consti 

 tution, profession, &c. ; the number of such divisions and the 

 amount of their divergence from one another being perhaps 

 very considerable. 



Now when we speak of either class as a whole and say 

 that nine- tenths die, the most natural and soundest mean 

 ing is that that would be the proportion if all without 

 exception went abroad, or (what comes to the same thing) if 

 each of these various subdivisions was represented in fair 

 proportion to its numbers. Or it might only be meant that 

 they go in some other proportion, depending upon their 

 tastes, pursuits, and so on. But whatever meaning be adopted 

 one condition is necessary, viz. that the proportion of each 

 class that went at the time the statistics were drawn up 

 must be adhered to throughout. When the class is homo 

 geneous this is not needed, but when it is heterogeneous the 



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