102 THE LAW OF BIRTHS AND DEATHS 



of the correlation on the whole is quite good enough for 

 the purposes of evolution, and it would be absurd to 

 expect mathematical regularity. There are a few apparent 

 exceptions to the general law that a declining deathrate 

 is accompanied by a declining birthrate. For instance, 

 during the first half of last century the figures for England 

 show a rising birthrate and a declining deathrate. But 

 the difference is small, and it is quite probable that the 

 apparent increase of the birthrate was due to improve- 

 ments in registration. 



A more difficult case is that of Ireland, where, according 

 to results obtained by Dr. T. H. C. Stevenson, 1 there has 

 been a marked rise of fertility, even when the necessary 

 allowances are made for the peculiar constitution of the 

 population as regards age and the number of young 

 married women. Assuming that all necessary statistical 

 factors have been taken into account, it is hardly possible 

 to express an opinion as to what may be the cause of 

 this peculiar result ; but it may be taken as fairly certain 

 that it is not to be found in religious influences, as Dr. 

 Stevenson suggests. It may be laid down as one of the 

 fundamental principles of sociology that the average man 

 will react to average circumstances in an average manner. 

 And whenever some special result is produced this must 

 be the result of special causes. An increase of the birth- 

 rate in Ireland is just as much in need of explanation 

 from those who believe that the fluctuations of the birth- 

 rate are the result of deliberate restrictive measures as 

 from those who believe that these matters are governed 

 by natural laws. The almost universal experience of 

 mankind in all ages is that with increasing prosperity 

 and a declining deathrate the birthrate also declines, and 

 this is as true of Roman Catholic as of other countries. 



J The Declining Birthrate, p. 350 et seq. 



