DESIGN IN THE ORGANIC WORLD. 415 



What we call " demonstration " rests entirely upon our mental 

 inability to accept as true anything that contravenes the thing 

 affirmed ; and if, in a chain of demonstrative reasoning, every 

 link has the strength of a necessary truth, we accept its conclusion 

 as having the same validity as the datum from which it started. 

 Now, I hold that exactly the same state of " conviction " may be 

 produced by a concurrence of probabilities, if these point sepa- 

 rately and independently to the same conclusion,— like radial 

 lines that converge from different parts of the circumference of 

 a circle, though none actually reach its centre. For the result 

 of that concurrence may be as irresistibly probative as any de- 

 monstration ; the conclusion to which they all point being one 

 which we are compelled to accept by our inability to conceive 

 of any other explanation of the whole aggregate of evidentiary 

 facts, though any one of them may be otherwise accounted for. 

 I am not aware that this principle has been discussed in any 

 treatise on logic ; but it is familiar to every lawyer who practises 

 in courts of justice; and its validity cannot, I think, be questioned 

 by any one who has studied the theory of what is commonly 

 called "circumstantial" evidence. Indeed, it would be difficult 

 to adduce a more remarkable example of the stability of an argu- 

 ment erected on a broad basis of independent probabilities, than 

 is presented in the wonderful fabric built up by the genius of 

 Darwin ; the general acceptance of the evolution-doctrine resting 

 on exactly the same kind of evidence as that on which I base 

 the argument from design. The most pronounced evolutionist 

 may be challenged to pro.iuce anything like a "demonstration" 

 of any one of his propositions. But (as I showed in my Sion 

 College address) the concurrence of probabilities suppHed by 

 morphology and embryology, by physiology and palaeontology, 

 is so complete as, in the minds of those most competent to 

 appreciate their probative value, to exclude any other hypothesis. 

 Those, therefore, who find in this concurrence a sufficient reason 

 for their assent to the doctrine of evolution, should be the last to 

 impugn the validity of the same mode of reasoning, when brought 

 to bear on the evidences of design which are afforded by the very 

 orderliness of that evolution. 



In applying this principle to the question we are now con- 



