BIOLOGY AND HUMAN PROBLEMS 



dabra. He has come to realize that the only form of truth 

 worth considering is what one might call man-truth. This 

 form of verity is based upon man's belief in the time-tried 

 doctrine of causation; it is tested by the five senses; it is 

 sifted by experience. It is a simple scheme, that of acquiring 

 knowledge by describing phenomena in terms with which 

 we are familiar and of determining the relation between 

 them; but it is the only one which has been found to be 

 continuously and invariably serviceable. 



Science makes, or endeavors to make, full use of the 

 human faculties; and, obviously, they are the only tools at 

 hand. But man is an imperfect creature; hence his gropings 

 have their limitations. Unfortunately, as soon as one 

 admits that scientific truth is relative and that the method 

 has its limits, these admissions are stretched and distorted 

 in a wholly illogical way. It is assumed that all findings of 

 science have the same degree of probability — or improba- 

 bility. Only too frequently science as a whole is held up to 

 ridicule because of the discarded hypotheses of physics, 

 chemistry, and biology. To scoff at these dead soldiers is 

 ill mannered, for many of them did good service in the 

 scientific advance; but to try to persuade the uncritical to 

 believe that all scientific discoveries are similarly short- 

 lived is criminal. For one insufficiently established theory 

 there are thousands of facts which will never be questioned. 

 They will stand as written, once and for all. 



It is also a popular pastime, particularly among those 

 most unfamiliar with the situation, to stake out the limits 

 to which science admits. The sign "No trespassing here" 

 is as familiar in the history of progressive thought as it is 

 along the country roadside. In the past it has been placed 

 over the estates of chemistry and physics; more recently 

 it has been shifted surreptitiously to the domains of 

 biology. Scientists have been told to restrain their curiosity 

 regarding heredity and intelligence and consciousness. 



[9] 



