52 THE SCIENCE OF LOGIC 



&quot; a. that the two processes cannot be kept rigidly apart. Whoever infers 

 from the facts of experience the conditions which- account for them must at the 

 same time in thought deduce those facts from those conditions. 



&quot; b. that what has been called Deductive Logic, what Inductive Logic has 

 been contrasted with, analyses forms of inference which, if the antithesis 

 between Induction and Deduction be thus understood, must be called in 

 ductive.&quot; 1 



He himself regards the mixed disjunctive argument as a typically induc 

 tive form of inference, owing to the use that is made of it in verifying an 

 hypothesis by the exclusion or elimination of alternative hypotheses. But he 

 suggests a deeper distinction between deductive and inductive inference : &quot; The 

 true antithesis is, as Aristotle saw, the antithesis between Dialectic and Demon 

 stration ; or in more modern phrase, between Induction and Explanation &quot;. 2 

 Inductive inference, then, would be the inference which convinces us that a 

 proposition is true (because certain facts are incompatible with any other 

 alternative), without, however, explaining -why it is true, without demonstrating 

 it ; while deductive inference would not only prove that a proposition is true, but 

 would also explain or demonstrate it, or, in other words, show us why it is 

 true. This is an intelligible and useful distinction ; but, obviously, it is based 

 on the matter of our inferences : it cannot be regarded as a distinction between 

 forms of inference, except in so far as some of the recognized forms of logical 

 inference are found to be more naturally applicable to matter in which we can 

 demonstrate our conclusions, and others to matter in which we can only set 

 up our conclusions as de facto true, without seeing why they are so. Now, 

 the disjunctive form of reasoning is, as we have seen, the form into which the 

 inductive verification of an hypothesis naturally falls. And to verify an hypo 

 thesis in this way is merely to show that it is true, without further explaining 

 it or showing why it is true : &quot; the essence of inductive reasoning lies in the 

 use of ... facts to disprove erroneous theories of causal connexion. It is 

 ... a process of elimination. The facts will never show directly that a is the 

 cause of x ; you can only draw that conclusion, if you show that nothing else is.&quot; 



&quot; You establish a particular hypothesis about the cause of a phenomenon, 

 by showing that, consistently with the relation of cause and effect, the facts do 

 not permit you to regard it as the effect of anything else (and mutatis mutandis 

 if you are inquiring into the effect of anything). It is this which makes the 

 reasoning merely inductive. If you could show in accordance with known or 

 accepted scientific principles that the alleged cause was of a nature to produce 

 the effect ascribed to it, your reasoning would be deductive ; . . . you would 

 be applying them to produce a conclusion which you see to be involved in 

 their truth ; and if we suppose the principles to be of such a nature that we 

 can see they must be true, then the conclusion will appear necessary, and a 

 thing that could not conceivably be otherwise.&quot; 4 



1 C/. JOSEPH, op. cit., p. 369. 



2 ibid., p. 369. &quot; The two antitheses.&quot; he adds, &quot; are not quite identical, because 

 some dialectical arguments are not inductive, and explanation is not demonstrative 

 unless the premisses from which it proceeds are known to be true. The reasoning 

 from those premisses is however the same, whether the premisses are known or 

 only believed to be true.&quot; ibid. n. i. 



3 ibid., p. 395. 4 ibid., p. 399. 



