156 THE SCIENCE OF LOGIC 



depend? It will evidently depend on the degree of likelihood 

 there is that the common characteristics are in reality causally 

 connected with the conclusion that is based upon them. And 

 on what does this likelihood depend? According to Mill, it 

 varies in proportion to the amount of resemblance between the 

 two phenomena, i.e. to the number of independent points of 

 similarity as compared with the number of independent points 

 of difference, and with the total amount of known and unknown 

 elements in the two phenomena. 1 But, not to speak of the 

 impossibility of &quot; counting &quot; the number of qualities assumed to 

 be &quot;independent&quot; of one another, this purely numerical test is 

 a very misleading one because it ignores the nature of the 

 characteristics, while it is precisely in their nature as active 

 properties, in their purpose or law? that their importance lies as 

 a basis or ground for inferring some further common bond of 

 law connecting the phenomena. 



Two phenomena may resemble each other in quite a multitude 

 of respects which may furnish no real ground for inferring re 

 semblance in any additional property. Two boys may be of the 

 same age, height, strength, colour of eyes and hair, have similar 

 home surroundings, and attend the same school. Yet from these 

 resemblances we cannot infer with any degree of probability that 

 because one of them is very talented so must the other be likewise. 

 It is not by the number but by the importance of the points of 

 resemblance that the strength of an analogy is to be estimated. 

 Now, their importance depends upon their nature as compared 

 with the nature of the additional property inferred in the con 

 clusion. &quot;Importance&quot; is a relative term. The points of 

 resemblance are &quot; important &quot; towards what is sought to be 



1 Logic, III., xx., 3. Cf. WELTON, op. cit., ii., p. 79. MELLONE, op. cit., p. 

 262. FOWLER, Inductive Logic, pp. 213-14. 



2 In determining the significance or importance of characteristics in relation 

 to one another we are aided very materially by the consideration that the laws of 

 their nature are an expression of the purpose or design they are intended to serve 

 (217). &quot;This is easily seen,&quot; writes Professor Welton, &quot;when the cases with 

 which an inference is concerned are the purposive works of man. For example, by 

 analogy we conclude that certain flints found in the earth are remains of weapons, 

 because they bear marks of artificial shaping of such a kind as to adapt them to be 

 cutting or piercing instruments, and corresponding, moreover, to those of flint 

 weapons made and used by savages at the present day &quot; (op. cit. t ii., p. 78). But 

 there is purpose in nature, organic and even inorganic (217), as well as in the works 

 of man. In botany and zoology many important laws have been brought to light 

 through analogies based on the connexion between the structure and development 

 of organs on the one hand, and the functions which it is assumed that they are intended 

 to discharge on the other. Cf. MELLONE, op. cit., p. 324. 



