102 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 2§ 
so, because it might be that the return on disaggregation after a 
certain point ceases to be worthwhile. 
My second comment has to do with the proposal towards agreeing 
on a terminology in which to discuss model construction. I have 
misgivings about that proposal. Scientific terminology generally 
comes about by a process very much like consumer’s choice in the 
market place; some authors use new terms that are picked up; the 
same authors may have used other terms that were not taken up. 
There is a social process of accumulation of terminology that is an 
extremely valuable screening process, not only of terms, but also of 
the ideas associated with these terms. If we make a concerted effort 
‘0 set up a terminology, we may find ourselves unwittingly and 
unwillingly setting up ideas rather than terms, because some terms 
are most suitable as vehicles for certain ideas. I would therefore put 
in a plea for allowing the natural selection of terminology to take 
its course also in this area. 
VIAHALANOBIS 
I should apologise for having failed to convey what I meant by 
:erminology. Sometimes we speak of « macro » and « micro » mo- 
dels. My point was that it would be useful to have, for example, 
an agreed terminology of using the two concepts « macro » and 
« micro » in relation to the particular domain of interest of which 
we are making a model. Now if we simply wait for general agreement, 
such agreement may never be reached. I may give a specific 
instance; in social accounts, in national income, it became necessary 
continually to have a standard terminology; for example, what should 
be meant by « net national income ». I suggested that model making 
has now reached a stage where an agreed terminology, in a purely 
scientific sense, would be extremely useful for purposes of description. 
[ think it is possible up to a point to have a terminology without 
Injecting any views in it. ... I may give a specific example. In 
my own country, we have distinguished between « projection » and 
« target ». « Projection » is what we get from historical experience, 
11 Stone - pag. 100