654 THE POPULAR SCIENCE MONTHLY. 



Even where deliberate measures are taken to obtain valid evidence 

 on any political or social question raised, by summoning witnesses of 

 all classes and interests, there is difficulty in getting at the truth ; be- 

 cause the circumstances of the inquiry tend of themselves to bring into 

 sight some kinds of evidence, and to keep out of sight other kinds. In 

 illustration may be quoted the following statement of Lord Lincoln on 

 making his motion concerning the enclosures of commons : 



" Tins I know, that in nineteen cases out of twenty, committees sitting in 

 this House on private bills neglected the rights of the poor. I do not say that 

 they wilfully neglected those rights far from it ; hut this I affirm, that they 

 were neglected in consequence of the committees being permitted to remain 

 in ignorance of the rights of the poor man, because by reason of his very 

 poverty he is unable to come up to London to fee counsel, to procure wit- 

 nesses, and to urge his claims before a committee of this House." {Hansard, 

 May 1, 1845. 1 ) 



Many influences of a different order, but similarly tending to ex- 

 clude particular classes of facts pertinent to an inquiry, come into play. 

 Given a question at issue, and it will very probably happen that wit- 

 nesses on the one side may, by evidence of a certain nature, endanger 

 a system on which they depend for the whole or for part of their live- 

 lihood ; and by evidence of an opposite nature may preserve it. By 

 one kind of testimony they may offend their superiors and risk their 

 promotion : doing the reverse by another kind. Moreover, witnesses 

 not thus directly interested are liable to be indirectly swayed by the 

 thought that to name certain facts they know will bring on them the 

 ill-will of important persons in their locality a serious consideration 

 in a provincial town. And while such influences strongly tend to 

 bring out evidence, say in support of some established organization, 

 there may very possibly, and, indeed, very probably, be no organized 

 adverse interest with abundant resources which busies itself to bring 

 out a contrary class of facts no occupation in danger, no promotion 

 to be had, no applause to be gained, no odium to be escaped. Con- 

 trariwise, there may be positive sacrifices, serious in amount, to be 

 made before such contrary class of facts can be brought to light. And 

 thus it may happen that, perfectly open and fair as the inquiry seems, 

 the circumstances will insure a one-sided representation. 



A familiar optical illusion well illustrates the nature of these illu- 

 sions which often deceive sociological inquirers : When standing by a 

 lake-side in the moonlight, you see, stretching over the rippled surface 

 toward the moon, a bar of light which, as shown by its nearer part, 

 consists of flashes from the sides of separate wavelets. You walk, and 

 the bar of light seems to go with you. There are, even among culti- 

 vated people, many who suppose that this bar of light has an objective 



* 



1 Quoted by Nasse, "The Agricultural Community of the Middle Ages," etc., English 

 translation, p. 94. 



