538 
PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 28 
rise to a decrease in the consumption of at least one good with 
no increase in the consumption of any other good: that is, 
(17 
a 
À < 0,9 
where 
; = [21/91, Z2/V2> <> EnlVn) 
Let us now assume that the working population grows at 
a rate depending upon the long-run equilibrium consumption y : 
The rate of growth of the labour force p is negative for very low 
level of vy, o for the subsistence level of y, and then increases 
with the rise in y until p reaches a certain maximum, after 
which p will decrease gradually but will increase again when ¥ 
reaches the level of an affluent society (4). 
We are now in a position to be able to fix the rate of in- 
terest (°). Measure the rate of growth of the labour force and 
the rate of balanced growth of outputs along the vertical axis, 
and the rate of interest along the horizontal axis. Consider- 
ing (17), we find that our assumption on the labour-force- 
growth-rate function implies the curve pg’ in Figure 1. On the 
other hand, as the rate of balanced growth of outputs equals 
the rate of interest, the relation between them is simply expres- 
sed by the 45° line. It is obvious that, to sustain the demand- 
supply balance of labour, the condition that the rate of balanced 
growth of outputs equal the growth rate of the labour force is 
to be fulfilled. It is seen from Figure 14 and 1b that there are 
at least one and at most three equilibria. The greatest equilib- 
(®) Let X be a vector; X<o (or X>0) means that all components of 
X are non-positive (or non-negative) and at least one of them is strictly 
negative (or strictly positive). 
(*) Professor S. C. TsrANG makes a similar assumption in his analysis 
of the Rostovian stages. See S. C. TsianG, 4 Model of Economic Growth 
in Rostovian Stages, « Econometrica », XXXII (1964), pp. 619-48. 
(>) A similar argument is found in my Equilibrium, Stabilitv and Growth, 
Ch. III (Oxford Clarendon Press. 1064). 
o| Morishima - pag. 10