380 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 28 
MALINVAUD 
No, I do not think that is correct. For instance in the linear 
logarithmic case with epsilon greater than 1, there is a whole family 
of paths which meets the recursive requirements and the sign restric- 
tions. Just one path satisfies condition 1 and is therefore optimal. 
HAAVELMO 
I have a somewhat strange question which may or may not be 
relevant to what Professor Koopmans said. It is this: it seems that 
political groups of powers often see it as their task to try to impose 
upon people, or to convince people that they should accept a smaller 
discount rate for evaluating the future gains from development 
projects than would appear to be the individual discount rate, and 
as time passes, people often say that the politicians were right. 
Now I have a feeling that this may have some connection with 
KoopMAN’s thesis, but I am not quite sure. 
ALLAIS 
I will begin with a few remarks relating to both papers. First 
point: both papers use a single preference function. Perhaps this 
may be useful, but it can be quite dangerous for a very drastic 
and very strong hypothesis is introduced into the models and some 
of the conclusions derived using this hypothesis can be questioned. 
Even if a single preference function could be assumed, the form of 
this preference function would be open to discussion. In the 
(*) From here on the discussion concerns both the paper presented by 
MALINVAUD and the earlier one presented bv KcopMANs 
-5] Malinvaud - pag. 80