268 



CLOUD 



400 



o 300 



E 

 o 



o 200 



Q 

 O 

 DC 

 Q- 



, United States 



, USSR 



, Japan 



, Germany 



, Great Britain 



Fig. 2 World pig-iron production (data from the U. S. Bureau of Mines 



Minerals Yearbook and the Encyclopaedia Brittanica). 



an optimal population as one that is large enough to realize and utilize the full 

 capabilities of man to generate a life of high quality for all people everywhere 

 but not so large as to threaten that quality or the emergence of the inventive 

 genius which is needed to create it. I would define quality of life as being a 

 function of the variety and flexibility of options available. Anything that 

 threatens or limits these options or restricts our ability or that of posterity to 

 exercise them threatens the quality of life. 



It is very hard to put meaningful numbers on such things, but I have tried to 

 create a sense of what is involved by inventing an index that I call the 

 Demographic Quotient, Q. I define Q. as being given by total resources available 

 on a continuing basis divided by population times per capita consumption: 

 Q= r/pc. No matter how else we may prefer to detail our individual concepts of 

 "quality of life," there is some general relation here that is worth thinking 

 about. If we could define some minimal level of consumption that went along 

 with a life of high quality, and if we knew the total resources available on a 

 sustained basis, then we would know the size of population that would be 

 sustainable given a fixed level of Q. You can also see that it is possible to keep Q. 

 constant by changing the variables on the right side of this equation. You can 

 increase the total resources available; or vou can increase the death rate, decrease 



