INTRODUCTION 17 



unfortunate that along with the development of theories as to 

 the causes of evolution no serious methodology has been 

 developed and very little attention has been paid to the 

 logical requirements of such inquiry. The ground is partly 

 covered by Woodger's admirable ' Biological Principles ' 

 (1929) ; but there is still need for an inquiry into the methods 

 of evolutionary research and the logical procedure by which 

 the main and subsidiary theories may be tested. 



