Assumptions 7 



We do not have to believe everything that we are told 

 about the past. We can choose to beUeve only what seems 

 to us reasonable, or we can frankly choose to believe only 

 those stories that please us. That is indeed the way most 

 people read history. They either believe everything they read 

 and ask for no evidence, or they believe only those things that 

 fit in with their preconceptions, whether political, national, 

 religious, or whatever they may be. 



The history of the earth cannot be read out of books in 

 the way that history of human events of the past can, since 

 the changes that have taken place in the waters and conti- 

 nents and glaciers and volcanoes occurred (as we infer) long 

 before there were any human beings to report the events. 

 The footprint which Robinson Crusoe saw in the sand was 

 a fact. That a human being had trodden the beach before 

 him was an inference. Similarly, the *' facts " which the 

 scientist observes are present to our senses; but we have to 

 consider them as evidence of what occurred in the past, and 

 draw our conclusions accordingly. These facts, about which 

 there can never be any dispute, we find in the very structure 

 and composition of the earth itself, in the fossils, in the beds 

 of salt and sandstone and various other minerals. People 

 differ only in the inferences and conclusions they draw from 

 the facts. 



Assumptions 



If it is possible to consider the historical past of the 

 earth and of its inhabitants in a common-sense way, it must 

 be by being clear in our own minds as to what we assume 

 about the world of matter and life. For facts do not speak 

 for themselves. They have to be assorted, pieced together, 

 related to other facts. In short, they have to be interpreted. 

 But such interpretation depends upon previous experience, 

 and especially upon what we assume to be the workings of 

 the world. 



The first of these assumptions which the scientist makes 



