154 KEASONING. 



Deduction. And we shall consider every process by which any thing is 

 inferred respecting an unobserved case, as consisting of an Induction fol- 

 lowed by a Deduction ; because, although the process needs not necessarily 

 be carried on in this form, it is always susceptible of the form, and must 

 be thrown into it when assurance of scientific accuracy is needed and de- 

 sired. 



§ 8. The theory of the syllogism laid down in the preceding pages, has 

 obtained, among other important adhesions, three of peculiar value : those 

 of Sir John Herschel,* Dr. Whewell,f and Mr. Bailey ;J Sir John Ilerschel 

 considering the doctrine, though not strictly "a discovery," having been 

 anticipated by Berkeley,§ to be "one of the greatest steps which have yet 

 been made in the philosophy of Logic." "When we consider" (to quote 

 the further words of the same authority) " the inveteracy of the habits and 

 prejudices which it has cast to the winds," there is no cause for misgiving 

 in the fact that other thinkers, no less entitled to consideration, have formed 

 a very different estimate of it. Their principal objection can not be bet- 

 ter or more succinctly stated than by borrowing a sentence from Archbish- 

 op Whately.|| "In every case Avhere an inference is drawn from Induc- 

 tion (unless that name is to be given to a mere random guess without any 

 grounds at all) we must form a judgment that the instance or instances ad- 

 duced ^XQ. sufficient to authorize the conclusion; that it is alloioable to take 

 these instances as a sample warranting an inference respecting the whole 

 class ;" and the expression of this judgment in words (it has been said by 

 several of my critics) is the major premise. 



I quite admit that the major is an affirmation of the sufficiency of the 

 evidence on which the conclusion rests. That it is'so, is the very essence 

 of my own theoi'y. And whoever admits that the major premise is only 

 this, adopts the theory in its essentials. 



But I can not concede that this recognition of the sufficiency of the evi- 

 dence — that is, of the correctness of the induction — is a part of the induc- 

 tion itself; unless we ought to say that it is a part of every thing we do, 

 to satisfy ourselves that it has been done rightly. We conclude from 

 known instances to unknown by the impulse of the generalizing propensi- 

 ty; and (until after a considerable amount of practice and mental disci- 

 pline) the question of the sufficiency of the evidence is only raised by a re- 

 trospective act, turning back upon our own footsteps, and examining wheth- 

 er w^e were warranted in doing what we have provisionally done. To 

 speak of this reflex operation as part of the original one, requiring to be 

 expressed in words in order that the verbal formula may correctly repre- 

 sent the psychological process, appears to me false psychology.^ We re- 

 view our syllogistic as well as our inductive processes, and recognize that 



* Review of Quetelet on Probabilities, Essays, p. 367. 



t Philosophy of Discovery, p. 289. 



X Theory, of Reasoning, chap, iv., to which I may refer for an able statement and enforce- 

 ment of the grounds of the doctrine. 



§ On, a recent careful reperusal of Berkeley's whole works, I have been unable to find this 

 doctrine in them. Sir John Herschel probably meant that it is implied in Berkeley's argu- 

 ment against abstract ideas. But I can not find that Berkeley saw the implication, or had 

 ever asked himself what bearing his argument had on the theory of the syllogism. Still less 

 can I admit that the doctrine is (as has been affii-med by one of my ablest and most candid 

 critics) ' ' among the standing marks of what is called the empirical philosophy. " 



II Logic, book iv., chap, i., sect. 1. 



*|[' See the important chapter on Belief, in Professor Bain's great treatise. The Emotions and 

 the mZ/, pp. 581-4, 



