SEMAINE D' ETUDE SUR LE ROLE DE L’ANALYSE ECONOMETRIOUE ETC. 
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nism and so on. And my conclusion is that the main reason for the 
difference in productivity between the United States and France, =c 
far as I can judge, is the play of the economic system. 
In any case I want also to answer some questions you raised 
and you did not mention just now. 
First I cannot affirm that there is only one explanation why 
the capital output ratio is practically constant. In my book « Eco- 
nomie et Intérét » (Chapter IX), I presented some other arguments 
relating to the CASSEL theory and taking into account the length of 
life, and I think these arguments are quite appealing. I would not 
say that there is only one explanation. I would suggest only that 
the stability, for practical purposes, of the capital output ratio can 
be explained by the constancy of @, which represents the intel 
lectual difficulty of conceiving roundabout production processes 
My present theory is thus at least compatible with the facts. 
Second, the coefficient ®, is, as I have already said, an index 
of the intellectual difficulty of conceiving roundabout production 
processes and psychologically, the thought that the coefficient © 
is constant over time because over time people have the same in- 
tellectual capacity to conceive roundabout processes, is appealing 
to me. Of course, I am suggesting an explanation, not offering a 
proof. 
Thirdly, LEONTIEF spoke about a possible cumulative effect. 
[ would say that I have done some quite interesting statistical 
research on the question of the intellectual capacity of people over 
time. More specifically, I have tried to assess the rate of growth or 
scientific and technological progress over time since the 12th century. 
[ have considered the number of major scientific and technological 
discoveries per century and the result of this statistical analysis, 
which I cannot develop here, is that we can conclude that people’s 
intellectual capacity has remained exactly the same since the 12th 
century. But, if one consider real wages, there have been tremendous 
fluctuations. Thus the commonly held view: that the extraordinary 
development of the West in the last century is due to new inventions 
is very questionable indeed. My opinion is that in fact the economic 
svstem has played a very great role 
Allais - pag. 201