298 Life ami Let tern of Fraucim Gal ton 



frequent than divergent ones. It is strange to notice how commonly this conception has been 

 ovt'rl(Xikt"<l l)y inetapliysiciana, ami how |iositive are their stat<'tiients that generalisations ai<' 

 impossible, and that the very idea of them is absunl. I will (juot<? tlie lucid writing of Sir W. 

 Hamilton to this effect, where he epitomises the opinions of other leading motapliysicinns. 

 I do so the more readily Ixvause I fully concwle that there is jx>rfect truth in what he says, 

 where the objects to be generalise<l are not what a cautious statistician would understand by 

 the word generic. Sir W. }Iamilton says {Lecliiret, ii, p. 297): 



'Take for example, the term num. Here we can call up no notion, no idea correspondinL: 

 to the universality of the class, or term. This is manifestly impossible. For as man involve.^ 

 contradictory attributes and as contradictions cannot exist in one representation, an idea or 

 notion adequate to nuin cannot be realise<l in thought. The class nuiii includes individuals, 

 male and female, white and black and copper coloured, tall and short, fat and thin, straight 

 and crooked, whole and mutilated, etc., and the notion of the cliuss muKt therefore at once 

 represent all and none of these. It is therefore evident, though the absuixlity was maintained 

 by Locke, that we cannot accomplish this; and this being im[>oasible, we cannot represent to 

 ourselves the class man by any equivalent notion, or idea.... This opinion, which after Hobbes, 

 has been in this country maintaine<l among others by Berkeley, Hume, Adam Smith, Camp 

 bell, and Stewart, appears to me not only true, but self-evident.'" 



To this Galton replies, demolishing by a concrete representation an 

 imposing philosophical dogma: 



" If Sir W. Hamilton could have seen and examined these com|)osite |iortraits, and had 

 borne in mind the well-known elements of statistical science, he would certainly have written 

 very differently. No doubt, if what we art; supposed to mean by the word iiian is to incluil< 

 women and children and to relate only to their external features and measurements, then tliu 

 subject is not suitable for a generic picture, other than of a very blurred kind, such as a child 

 might daub with a paint-brush. If, however, we take any one of the principal races of man 

 and confine our portraiture to adult males, or adult females, or to children whose ages lie 

 between moderate limits, we ought to pro<luce a good generic represi>ntation." 



Bold indeed to face the metaphysician in his own cave, and as-sert that 

 his generic pictures were as those of a child daubing with a paint-brush, 

 solely because he had not adequately, i.e. statistically, defined what was to 

 be understood by a genus, and a generalisation ! It is the old tale of the 

 scientist, analysing phenomena, coming up against the metaphysician bandy 

 ing words'. No wonder that Galton s psychology was of small influence with 

 philosophising dialecticians ! 



(B) Photographic Bi-projection, Indexing of Profiles, etc. 



As late as April, 1888, Galton was still thinking over composite photo- 

 graphy. In his earlier work he had made the vertical distance Ijetween the 



' My friend Professor W. P. Ker warns me to avoid an ignoralio eleiichi. It seems to nu- 

 that any argument would turn on how far the "general idea" is that of a limited class. I feel 

 sure that Berkeley and I think Hamilton would have argued that the abstract idea of ii 

 Jewish Boy was impossible. Yet Galton shows that we can form a concrete image of such a 

 Boy, and he sees no reason why we should not, if so constituted, visualise hiui. BerkelcN 

 (Workt, Vol. I, pp. 76-7, 184.3) confesses that what other minds can do, he knows not, but \u 

 himself cannot abstract the qualities from a number of individuals and conipouii<l them to .i 

 general notion. Both Berkeley and Hamilton surveyed their own minds, and they do no: 

 appear to have experimented on the visualising faculty of other minds. 



What (talton asserts is that it is fwssible t<> reach a general idea or a generic image pro 

 vided the individuals generalise*! form a limited class or yemts, and he holds that the nieta 

 physicians, proceeding purely by introspection, had overlooked the statistical criteria for the 

 homogeneity of a group or genua. 



