Introduction xv 



tion " as an article of faith — an article of faith in conflict 

 with prevailing beliefs and assumptions, and yet necessary 

 for salvation or for some other benefit. Such enthusiasts, 

 concerned more with a spread of sound doctrines than with 

 the promotion of clearer thinking, have often been quite as 

 dogmatic as those who resist conversion. They have been 

 as much disposed as any dogmatists to appeal to authorities 

 and to ** arguments " rather than to the facts themselves. 

 The results have been an overemphasis upon the value of 

 opinions and a confusion as to the meaning of evolution as 

 understood by scientists. 



Further misconceptions arise from the difficulty of 

 maintaining always an objective and impersonal attitude. 

 Even professional scientists confronted with a public asking 

 to be educated (or at least shown) have been disposed to 

 diverge from the main issue to discuss theories and specula- 

 tions which the layman confuses with the major principles. 

 Or they have quarrelled among themselves as to technical 

 matters that do not affect the main question, regardless of 

 how they are settled. To this day, people who ought to 

 know better assist the uninformed in confusing the idea 

 that the world is constantly changing with Darwin's effort 

 to explain how new species arise. To this day, professional 

 scientists wrangle among themselves as to the practical ap- 

 plication to be made of certain purely theoretical principles. 

 In this way they impress the uninformed not with the una- 

 nimity among the scientists about the fact of the evolution 

 of life, but with the disagreements among scientists — about 

 something or other that has to do with evolution. In dis- 

 cussing principles of heredity, principles of morphology, 

 principles of embryology, or in attempting to interpret a 

 newly discovered fossil, the play of personal opinion, the 

 wide range of speculation, and the necessarily large amount 

 of disagreement as to many details bring, to the general pub- 

 lic, nothing at all of the meaning of the discussions, but only 

 an intimation that the evolutionists are quarrelling or that 

 there is a " crisis " in evolutionary thought. 



