170 WHAT IS SCIENCE? 



are considering is best met by a counter-offensive. It 

 sounds plausible to maintain that those who have had 

 the greatest experience of any matter must know most 

 about it. But, like many other plausible doctrines, this 

 one is absolutely false. No popular saying is more 

 misleading than that we learn from experience ; really 

 the capacity of learning from experience is one of the 

 rarest gifts of genius, attained by humble folk only by 

 long and arduous training. Anyone who examines 

 carefully any subject concerning which popular beliefs 

 are prevalent, will always discover that those beliefs 

 are almost uniformly contradicted by the commonest 

 everyday experience. We shall not waste our time if 

 we devote a few pages to discovering the sources of 

 popular fallacies, and considering in what manner they 

 can be corrected by scientific investigation. When 

 we have established how little worthy of confidence is 

 " practical knowledge " we shall be in a position to see 

 the value of " theory." 



POPULAR FALLACIES 



The most frequent source of such fallacies is a disposi- 

 tion to accept without inquiry statements made by 

 other people. Error from this source is not wholly 

 avoidable ; except in the very few matters in- which we 

 can interest ourselves, we must, if we are to avoid blank 

 ignorance, simply believe what we are told by the best 

 authority we can secure. And since nobody is always 

 right, we shall always believe some false doctrines 

 however carefully we choose our authority. But it 

 is very remarkable how people will go on believing things 

 on authority, when the weight of that authority is quite 

 unknown, and when their belief is flatly contradicted 

 by experience. I know a family, not without intelligence, 

 who, until their statement was challenged in a heated 



