SEMAINE D'ÉTUDE SUR LE ROLE DE L'ANALYSE ECONOMETRIQUE ETC. 
20. 
population were to increase to such an extent that just space on 
which to exist would become very scarce, and it might actually be- 
come a problem well before that. It seems however that technology 
has so many possibilities for food production that are less land- 
intensive than the ones that are now being used, chat there might 
be at least a temporary offset in technological progress. 
As to the assumption that capital does not depreciate, I think this 
is a difference in degree but not in kind. As Pro:. DORFMAN indi- 
cates you can indeed reinterpret A as the sum A=), +X, where 
)., refers to population growth and }, to capital depreciation 
MALINVAUD 
I should like to argue that Prof. Koopmans has been quite wise 
in these kinds of simplifications. We are certainly not living in a 
one commodity world in which capital would not depreciate. But 
some of the difficulties of intertemporal choices will appear with 
full clarity in very simple models. At the present stage of our 
research we are therefore justified to study carefully and exhaustively 
such simple models. 
In particular it seems to me that difficulties occurring in more 
complex models have not been fully understood in their natures, 
because several sources of complications mixed their effects, and 
the origin of each new result was not clear. From the point of view 
that interests Prof. Koopmans, I do not think we should reach dif- 
ferent qualitative conclusions if we introduce many commodities, if 
we assume that capital depreciates, or if we take into account the 
fact that land is not reproducible 
PASINETTI 
I have very much enjoyed Prof. KcopMaNs' skilful, elegant anc 
perspicuous analysis. Yet, I find it hard to accept his conclusions, 
which seem to me best summarized by the title of his section 
4 | Koopmans - pag. 67