772 



SCIENCE. 



[N. S. Vol. II. No. 49. 



' dogmatist ' by pious vitalists than to pretend 

 to know what we do not know. 



One of these correspondents says (Oct. 18th, 

 p. 521-2) that the opinions I had quoted are a 

 ' scafTolding ' which the builder will not con- 

 found with his more permanent edifice ; and, 

 furthermore, that I fail to discriminate between 

 volition and consciousness, and am no psycholo- 

 gist. 



As I plead guilty to this latter charge I gladly 

 take this opportunity to ask the ' Psychologist ' 

 a few questions, although I fear lest, in my 

 ignorance, I may be like the patient who endows 

 his wise old family doctor with more power 

 than he really possesses. 



Will the ' Psychologist ' tell me, in the first 

 place, how any one who does not use the words 

 in a Pickwickian sense can aifirm that "when 

 the protozoa seek oxygen they have to be aware 

 that they need it, and must have some knowledge 

 of the fact when they get it," without believing 

 that the said protozoa are both conscious and 

 endowed with volition ? 



I am greatly surprised to find in the same 

 communication (p. 522) the statement that 

 ' ' every naturalist knows that consciousness is a 

 property of protoplasm." 



If I were to disclaim any knowledge of this , 

 sort I should, no doubt, be told I am no natural- 

 ist, but I think no one will make this reply to 

 Huxley, who tells us "We may all have our 

 opinions as to whether mental phenomena have 

 a substratum distinct from that which is as- 

 sumed to underlie material phenomena or not, 

 though if any one thinks he has demonstrative 

 evidence * * all I can say is, his notion of 

 demonstrative evidence diifers from mine." 



I have myself been somewat disturbed in 

 mind by the thought that, while we are bound 

 to find jvist principles which will command the 

 assent of all thinking men, no less than three 

 mutually exclusive opinions on this matter 

 are current among naturalists. Is it possible 

 that the correspondent holds that these three 

 are one ; or is the statement that ' every natur- 

 alist knows ' so and so only a ' scaffolding, ' to 

 be torn down when the writer sees fit? 



Without dwelling on this point I wish to ask 

 the ' Psychologist ' how, if consciousness is a 



a ' property, ' a ' conscious state ' can be an 

 ' agency. ' Can the writer mean that it is the 

 ' state ' and not the consciousness which is the 

 'agency,' or how does the 'Psychologist' in- 

 terpret these hard sayings?' 



The writer seems to me to be undertaking a 

 difiicult feat, which I shall watch with some ex- 

 citement — the attempt to ride at the same time 

 the most rampant steeds of both materialists 

 and vitalists. 



This correspondent attempts to emend my 

 request for evidence that consciousness and 

 volition can cause structure or anything else, 

 by substituting for the words ' anything else ' a 

 specific case (p. 522). I therefore ask the 'Psy- 

 chologist ' whether this concrete statement of 

 the problem of volition makes it any easier to 

 solve. 



My modest request for evidence that con- 

 sciousness and volition can cause anything is 

 more roughly handled by another correspond- ^ 

 ent (P. 554), who attributes to me, in quotation •- : 

 marks, the assertion that ' consciousness and vo- 

 lition cannot cause structure or anything else.' 



This correspondent fills two pages of Science 

 with an accusation of dogmatism, which would 

 be no more than my just due if I had ever made 

 the statement which he so skilfully constructs 

 out of my words. 



We are told that it is a maxim for practice in 

 certain circles to ignore all your opponent says, 

 and to answer what he does not say ; but this 

 style of reasoning is no ornament to the pages 

 of a scientific journal, least of all one which had 

 already printed and might have verified the 

 statement which is misquoted. 



In the article to which these correspondents 

 refer I insisted that the test of truth is evidence 

 and not conceivability ; and I illustrated, by the 

 inversion of the retinal image, the fact that evi- 

 dence may furnish conclusive proof of truths 

 which are inconceivable. 



The question whether this illustration is well 

 chosen or ill chosen has, of course, no bearing 

 upon the accuracy of the general statement, 

 and it seems to me that attention has been di- 

 rected from the main issue by the comments 

 which have been made upon the illustration, al- 



