A NEW EPISTEMOLOGY 227 



greater point to the description — so that we may not 

 miss seeing the wood for the trees. 



By employing the known physical laws expressing 

 the uniformities of Nature we can to a large extent 

 dispense with this army of watchers. We can afford to 

 let the moon out of sight for an hour or two and deduce 

 where it has been in the meantime. But when I assert 

 that the moon (which I last saw in the west an hour ago) 

 is now setting, I assert this not as my deduction but as 

 a true fact of the scientific world. I am still postulating 

 the imaginary watcher; I do not consult him, but I 

 retain him to corroborate my statement if it is chal- 

 lenged. Similarly, when we say that the distance of 

 Sirius is 50 billion miles we are not giving a merely con- 

 ventional interpretation to its measured parallax; we in- 

 tend to give it the same status in knowledge as if some- 

 one had actually gone through the operation of laying 

 measuring rods end to end and counted how many were 

 needed to reach to Sirius; and we should listen patiently 

 to anyone who produced reasons for thinking that our 

 deductions did not correspond to the "real facts", i.e. 

 the facts as known to our army of measurers. If we 

 happen to make a deduction which could not conceivably 

 be corroborated or disproved by these diligent measur- 

 ers, there is no criterion of its truth or falsehood and it 

 is thereby a meaningless deduction. 



This theory of knowledge is primarily intended to 

 apply to our macroscopic or large-scale survey of the 

 physical world, but it has usually been taken for granted 

 that it is equally applicable to a microscopic study. We 

 have at last realised the disconcerting fact that though 

 it applies to the moon it does not apply to the 

 electron. 



It does not hurt the moon to look at it. There is no 



