432 



NATURE 



[December i, 192 i 



Letters to the Editor. 



]Th.e Editor does not hold himself responsible for 

 opinions expressed by his correspondents. Neither 

 can he undertake to return, or to correspond with 

 the writers of, rejected manuscripts intended for 

 this or any other part of Nature. No notice is 

 taken of anonymous communications.] 



Relativity and Materialism. 



Prof. Wildon Cark lias for a number of years 

 been busily engaged in ringing the death-knell of 

 materialism. I was therefore not a little surprised to 

 read in Nature (October 20) his statement that 

 Einstein's theory was the "death-knell of material- 

 ism." I thought, from my previous acquaintance 

 with Prof. Carr's writings, that Bergson, Croce, and 

 others had already done all that was necessary' in that 

 direction. But no ! Prof. Carr has resuscitated it 

 for the express purpose of killing it once more. That 

 unfortunate doctrine seems to exist mainly for the 

 purpose of being periodically slaughtered by professors 

 of metaphysics ; and we are led to the conviction that 

 materialism must have very singular properties to 

 sur\'ive so many tragic executions. 



Well, it does possess a property which must 

 naturally appear singular to those steeped in meta- 

 physics — it happens to be true. Scientific material- 

 ism, as now understood, does not profess to be a 

 rounded or final system of philosophy : it is merely a 

 name for a few general principles, laid down by 

 science, and selected for emphasis on account of their 

 high human significance. Science makes new know- 

 ledge ; philosophy (rightly understood) does not ; it 

 simply collects together certain principles yielded by 

 science, those principles being selected as having some 

 bearing on the deep undying problems of most pro- 

 found human interest. 



Among the scientific principles thus selected and 

 emphasised by materialism — and the onlv one among 

 them still seriously controverted — is that which states 

 that mind cannot exist apart from matter, or as 1 

 prefer to put it, that mind is a function of material 

 organisms. Prof. Wildon Carr is of opinion that 

 mind can and does exist apart from matter; and he 

 is under the impression that this opinion is justified 

 by the principle of relativity. So far as I can follow 

 his argument, it amounts to this. Space and time 

 are relative to the observer; therefore the existence of 

 an observing mind must be antecedent to the exist- 

 ence of space and time. True ; but space and time 

 are not matter : they are not objective things ; you 

 cannot weigh them or touch them ; they are part of 

 the mental framework which we erect for our con- 

 venience in dealing with external nature. They are 

 concepts; just as the number 10 is a concept; not a 

 thing, but a framework into which things can be 

 fitted. " For the concept of relative space-time 

 systems the existence of mind is essential." Prof. 

 Carr might with equal profundity have said that for 

 the presence of dew the existence of water is essen- 

 tial. Dew is aqueous; a concept is mental; but let 

 me inform Prof. Carr that neither one nor the other 

 of these propositions gives the slightest qualm to any 

 scientific materialist, nor have they the least relevance 

 to the question whether or not mind depends upon 

 matter. We are not concerned with "concepts," 

 which, of course, imply the previous existence of 

 mind, but with objective things. 



Now Prof. Carr argues that the " space-time 



NO. 2718, VOL. 108] 



system," involved by relativity, is conditional on the 

 existence of mind. Very well' then. It follows that 

 if mind were to be extinguished throughout the uni- 

 verse, the laws at present ascribed to the universe 

 would cease to operate, or perhaps the universe itself 

 would cease to exist. Now that is an altogether in- 

 credible proposition. If Prof. Carr's mind were to 

 be extinguished, the laws of nature would still re- 

 main as they are. If everybody else's mind were 

 also to be extinguished the laws of nature would be 

 unaltered. "Concepts " would vanish no doubt; but 

 the validity of the principle of relativity itself does 

 not depend on the existence of a mind which can 

 testify to it. Prof. Carr exhibits that incurable con- 

 fusion between concepts and objects which is 

 common to all those who think that metaphysics is 

 a rival method of science in the making of new know- 

 ledge. 



Relativity of space and time no more conflicts with 

 scientific materialism than does relativitv of motion. 

 But it is idle to argue with sentiment, and it is 

 with sentiment alone that we have to do — sentiment 

 urtsupported by a fragment of evidence, and asserting 

 itself in flat contradiction to every principle of logic. 

 .'\s a mere statement of truth, materialism will always 

 reign, as it has reigned now for centuries as the basis 

 of scientific experiment. But on a show of hands it 

 will always be in a minority ; its reign is that of an 

 uncrowned king. There exists a wide and universal 

 human sentiment which loathes materialism. That 

 sentiment comes out in many different forms : in 

 the vulgar superstitions of the uneducated, in spiritual- 

 ism, in metaphysical dissertation. I'hey are but the M 

 same deep sentiment on different intellectual grades, t 

 but as false and rotten in the higher grades as they 

 are in the lower. Everywhere it comes out : in 

 physiology we find it as vitalism ; among the public at 

 large it supports religion, the most powerful single 

 factor that has moulded the destinies of civilised 

 humanity. Materialism must always be unpopular; 

 that is why it is so often being killed. But it is true ; 

 that is whv it never dies ; that is why it never will 

 die; unless, indeed, it is one day drowned in the 

 floods of oilv sentimentalism. 



Two .hundred and fifty years ago the world of 

 physics was fermenting as it is now. Newton was 

 introducing a revolution of thought, comparable to 

 the revolution of the last twentv years. Then, as 

 now, the sudden upsetting of old ideas had in some 

 sense a demoralising effect. There seems a real 

 danger that metaphysics may take root, for a brief 

 period, amid the general disorganisation consequent 

 upon the revolution. A spectator does sometimes see 

 most of the game, and I trust it may not be con- 

 sidered presump>tuous in a spectator to sound an old 

 note of warning at a time when manv insidious inva- 

 sions of science are being attempted by metaphysics : 

 "Phvsics, beware of Metaphysics." 



November 18. Hugh Elliot. 



Metallic Colouring of Beetles. 



In reference to Mr. Onslow's letter on this subject 

 in Nature of November 17, I mav say that it requires 

 some care to prepare specimens for the pressure test. 

 The chitinous coat is thick, and is softer below than 

 it is at the colour-producing surface. The inner layers 

 should be removed so far as possible, and the test- 

 piece (which should not exceed 1/50 in. in diameter) 

 cut from the remaining part. 



In mv experience, when these conditions are 

 attended' to the colour vanishes under pressure, and 



