316 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 28 
so that in the existing state of knowledge, even if the gratuitous 
assumption of rapid series convergence is made, the possibility 
of making a serious estimate of the constant & appears to be out 
of the question. 
At the same time, it should be clearly understood that these 
difficulties do mot arise from the model itself but ave inherent 
in the nature of things. 
2. 
JUSTIFICATION OF THE GENERAL MODEL WITH RESPECT TO ITS 
HYPOTHESES 
General Model - Hypotheses (a), (b) and (c) 
The general model is based on three hypotheses: 
(a) Paretian optimum and invariance of the difference 
(8) - pl), 
(b) unchanging production elasticities and 
(c) a steady rate of growth p of primary income R, (§ 210- 
211 and 230). 
Hypothesis (a) 
315. The assumption of a Paretian optimum can be accepted 
as a first approximation, at least insofar as equivalence over 
time of primary inputs and the comparison in time of their 
relative productivity is concerned. 
The hypothesis that the difference i(¢) - p(¢) is invariant is 
an asymptotic property of capitalistic processes which can be 
demonstrated on the basis of very general assumbtions (1). 
(”) Arrats (1962 A) p. 702, ALLAIS (1963) $ 117 and 127 and ArrLals 
1964) $ 43. 
1] Allais - pag. 120