SCIENCE AND THE UNOBSERVABLE — DINGLE 213 



knows it. But Einstein says he does not know it, and Einstein is an 

 honorable man. And the only reply is that Einstein and his followers 

 must be speaking as physicists. 



We can now press home the point. We agree, let me assume, that 

 science and philosophy are better without the binkum ; how, then, can 

 we exclude him? Only, says Counsel for the defence of the principle, 

 by refusing to grant existence to anything that is essentially unobserv- 

 able. Our only clue to reality is observation in one form or another. 

 And if we admit that, we must go further. Not only must we deny 

 existence to the unobservable: by the same token we are forced also to 

 deny any unobservable property to an existent thing, otherwise we 

 again open the door to the same abuses. And that means that every- 

 thing whose existence we acknowledge must be definable ultimately in 

 terms of observation — that for everything that we assert about it we 

 must have, in the last resort, some observable evidence. The charac- 

 ter of the thing may, of course, be very different from the character of 

 the observation ; a star, for instance, may be a dazzlingly bright globe 

 of gas millions of miles in diameter, whereas we observe only a faint 

 pinpoint of light. But there must be a logical passage from every de- 

 tail we assert about the star to the observation of the pinpoint or other 

 observations of cognate character. If there is the slightest relaxation 

 of this requirement, in comes the binkum with passport signed and 

 sealed. 



The case seems established, but we must hear Counsel for the other 

 side. His argument is a reductio ad absurdum. Certainly we do not 

 want the binkum, he says, but your device for keeping him out is both 

 presumptuous and absurd; you are throwing out the baby with the 

 bath-water. Consider for a moment what your principle implies. 

 It asserts that there is nothing in the universe except what you can 

 observe — nothing in the physical world beyond the reach of your 

 senses. Suppose we were blind, like the men in Mr. Wells's country; 

 then, according to your principle, we ought to act as they did, and 

 deny existence to the merely visible. How do you know that the 

 universe does not contain things apprehensible only by senses which 

 you do not possess, which perhaps you have lost in the course of evolu- 

 tion or have not yet acquired? Moreover, what about the past? 

 You cannot observe that, for it has gone; therefore, you say, it has no 

 meaning, it must not come into our description of reality. No flower 

 has been born to blush unseen ; no feet trod the earth before the begin- 

 ning of living memory. Such nonsense necessarily follows if your 

 principle is granted. Exclude your binkum by all means — we hold no 

 brief for him ; but find some sensible way of doing it, without assuming 

 potential omniscience. 



The problem, I think, is now set clearly before us. If we admit the 

 unobservable, there is no check on empty speculation; if we reject the 



