SECTION 17. INDUCTION. 137 



and upon that you have founded a deduction, and reasoned out the special 

 conclusion of the particular case. Well now, suppose, having got your law, 

 that at some time afterwards you are discussing the qualities of apples 

 with a friend, you will say to him, 'It is a very curious thing, but I find 

 that all hard and green apples are sour!' Your friend says to you, 'But 

 how do you know that?' You at once reply: 'Oh, because I have tried 

 them over and over again, and have always found them to be so.' Well, 

 if we were talking science instead of common sense, we should call that 

 an experimental verification. And, if still opposed, you go further, and 

 say: 4 I have heard from the people in Somersetshire and Devonshire, 

 where a large number of apples are grown, that they have observed the 

 same thing. It is also found to be the case in Normandy, and in North 

 America. In short, I find it to be the universal experience of mankind 

 wherever attention has been directed to the subject.' Whereupon your 

 friend, unless he is a very unreasonable man, agrees with you, and is 

 convinced that you are quite right in the conclusion you have drawn. 

 He believes, although, perhaps, he does not know he believes it, that the 

 more extensive verifications are that the more frequently experiments 

 have been made, and results of the same kind arrived at that the more 

 varied the conditions under which the same results are attained, the more 

 certain is the ultimate conclusion, and he disputes the question no further. 

 He sees that the experiment has been tried under all sorts of conditions, 

 as to time, place, and people, with the same result; and he says with 

 you, therefore, that the law you have laid down must be a good one, and 

 he must believe it. 



"In science we do the same thing the philosopher exercises precisely 

 the same faculties, though in a much more delicate manner. In scientific- 

 inquiry it becomes a matter of duty to expose a supposed law to every 

 possible kind of verification, and to take care, moreover, that this is done 

 intentionally, and not left to a mere accident, as in the case of the apples. 

 And in science, as in common life, our confidence in a law is in exact 

 proportion to the absence of variation in the result of our experimental 

 verifications." (Twelve Lectures and Essays, ed. 1915, pp. 39-41.) 



First of all, note the fact that the effects of eating mince 

 pies are notorious ; and that, therefore, the argument begs the 

 question. Secondly, a "plain man" who remembered all appo- 

 site facts so completely and correctly, would be looked upon as 

 a nine days' wonder among plain men. Thirdly, as De Morgan 

 had pointed out, the plain man did not consider the effect of 

 a mixture in the diet. The following instance, perhaps, more 

 nearly typifies unaided reasoning concerning matters unknown, 

 and betokens simultaneously where Bacon's rules are sinned 

 against. Some one typifying vast multitudes had recourse to 

 a certain universal patent medicine for a certain ailment and 

 recovered; therefore that patent medicine, he tacitly concluded, 

 had cured him and will cure everybody of all ailments. Some 

 other universal patent medicine which he had tried previously 

 to this one, was not connected, so he surmises, with his reco- 

 very, therefore all other patent medicines are ineffective, if not 

 injurious. Or to mention a humorous case cited in an English 

 court of law during 1914 : A typhoid patient having recovered 

 despite of eating herrings, a medical student entered in his 

 diary the words: "Herring cures typhoid." Shortly afterwards, 

 whilst in Prance, this same student benevolently prescribed 



