Certainty Beyond Facts 5 



caviar is indigestible. The soundness of your ideas has no 

 connection with the certainty that you feel about them. 

 The soundness depends upon the number and range of facts 

 upon which they rest. Everybody must have noticed that 

 some people feel sure about many things that are not so at 

 all. On the other hand, many people hesitate to speak posi- 

 tively even when they are well supported in their ideas. Our 

 feelings, apparently, cannot be relied upon to make sure that 

 what we firmly believe is really true. 



It is common sense to feel sure about many things that 

 we have not actually observed directly. It is a little better 

 than common sense to make sure how reliable our generaliza- 

 tions are. 



Certainty Beyond Facts 



The facts that we know about living plants and animals, 

 and the facts that we have been able to gather about dead 

 ones, lead to the generalization that the living forms of a 

 given period are the descendants of the living forms of an 

 earlier period. Probably no sane adult questions this. A 

 second generalization is that in the course of time the de- 

 scendants of plants and animals have become so modified as 

 to constitute " species " distinguishable from the ancestral 

 types. This is really the core of the evolution controversy. 

 Instead of calling this process " evolution " we call it develop- 

 ment, or, as concerns organic forms, continuity of life with 

 modification, or descent with modification. When we use 

 the term evolution in this sensQ it is without prejudice as to 

 the origin of the process, as to the course which the process 

 has run or will run, as to whither it will lead, or as to the 

 catises or forces which bring about the changes observed. 



Now it must be freely admitted that when doubters 

 ask for " proof " of this evolution, it is quite impossible to 

 furnish it, since the historical past is always a matter of in- 

 ference or conjecture, with more or less of probability to 

 qualify it. Did George Washington ever live, or, having 



