76 EVIDENCES AND LIMITATIONS 



wider investigation; but to accept the best available 

 working hypothesis because of its present working value 

 is a truly scientific procedure, and upon such acceptance 

 depends to a large degree the possibility of scientific 

 progress.^ 



The method by which a scientific hypothesis is arrived 

 at and established is inductive. That is, facts are in- 

 dustriously collected and co-ordinated in their apparent 

 relations, and speculative imagination is exercised to 

 devise a theory which will fit in with and, to some 

 extent at least, explain the facts that have been accu- 

 mulated. The process involves an element of con- 

 jecture and guesswork, followed, to borrow a figure 

 from the tailor's work, by trying the new garment on 

 to nature's model in order to discover how it fits. If 

 it fits well, it is accepted; if imperfectly, it is modi- 

 fied; if not at all, it is rejected and another theory is 

 devised. We must accept this method, and be con- 

 trolled in our views of nature by its results, or else aban- 

 don hope of acquiring a scientific knowledge of nature. 



The evolutionary hypothesis has been arrived at by 

 induction. A very great mass of biological data has 

 been gradually accumulated by the labours of succes- 

 sive generations of scientific investigators; and the 

 thought that the origin of species can best be explained 

 in its physical aspects by the supposition that existing 



^ Cf. pp. 33-34, above. 



