no SCIENCE PROGRESS 



argument (which he has ignored) to which I drew attention in my first letter, 

 namely : "... We know about brains through perception alone. So far 

 as we are concerned, a brain is simply a group of sense-data, and the 

 perception of it presupposes the existence of a perceiving mind. Materialism 

 is thus a gigantic va-repov Trporepov " ? 



Yours faithfully, 



C. A. Richardson. 

 January 20, 1920. 



II— REPLY 



From THE WRITER OF THE ESSAY-REVIEW 



Dear Sir, — In his first paragraph your correspondent indulges in a familiar 

 dialectical device when he states that my previous communication is a 

 " torrential polemic " in reply to his former letter. It was nothing of the 

 kind. As indicated by its title, it was a general Plain Statement of the. case 

 against the ghost-hypothesis, and it referred to him only incidentally. I 

 did not discuss his " crucial points " because I could find none, and was 

 content to leave most of his other points to the intelligence of your readers. 

 On the other hand, his letters are professedly criticisms of mine, and yet he 

 ignores nearly all my points and reiterates his own — which are neither new 

 nor sound. 



I quite agree with the first part of his second paragraph. The question 

 involved is an elementary actuarial one. By well-known rules, if out of 

 X seances y seances are shown to be frauds, then the chances that the remainder 

 are frauds increase greatly as y increases. And this presumption is vastly 

 increased if the unconvicted seances are of the same type as the convicted 

 ones, as they evidently are ; and is further increased if a conjuror can do 

 all the tricks shown in both classes— of which I think Mr. Nevil Maskel5me's 

 letter in your issue for January last will satisfy most ordinary people. Lastly, 

 the presumption is still further increased by the inherent absurdity — even 

 the ridiculous absurdity — of the whole ghost-hypothesis when examined in 

 the light of the ordinary facts around us (as I showed in my previous letter) ; 

 and I conclude that the chances against any seance being genuine are, let 

 us say, millions to one (" actuarial certainty " is put only at 49,999 to i). 

 This is my whole case. The spiritualist retorts that even such odds do not 

 amount to absolute proof. He is there quite right ; but then he generally 

 adds that, as we cannot absolutely prove that some stances are not genuine, 

 therefore some seances are genuine ! — in fact, nearly all his case rests on this 

 argument — a monstrous infringement of the elementary laws of reasoning 

 and a typical case of the sit-ergo-est fallacy. 



But if he is not so ignorant as to make such a mistake, he says merely, 

 " As you cannot prove that all seances are not genuine, why don't you in- 

 vestigate them ? " This is really almost as foolish a position as the other. 

 If the chances are n to i against the truth of an hypothesis, then the 

 chances are n to i that we shall waste our time in investigating it. If w 

 is very large, as in the case of the ghost-hypothesis, then the chances are 

 that many men might waste all their lives investigating it. Even if a man 

 takes the risk, what then ? If he succeeds in exposing a number of seances, 

 the spiritualist merely repeats his parrot cry and maintains that the seances 

 which were not exposed were genuine ; and if he fails in exposing others, 

 the doubt always remains that the medium was too clever for him. And 

 yet these people have the assurance to ask him to waste his life over the 

 foolish enterprise, and the impudence to assert that he cannot form any 

 conclusions on the matter unless he consents to do so. That is the whole 



