674 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 28 
ment and development. To an external observer, looking for 
the « best-known technique », the methods of production may 
sometimes look like being introduced at a certain point and 
then remaining stable for long periods of time; but when a 
reckoning of the inputs and outputs of an industry is begun, 
the most widely warying shifts are found from one moment to 
the next. Even at a given point of time, there are many direc- 
tions from which the inputs may come, and to which the outputs 
may go. 
These are well-known problems which have always caused 
difficulties to all builders of input-output tables and which some- 
times cast serious doubts on the meaning to be attributed to 
the coefficients of very disaggregated input-output systems. Of 
course these doubts diminish the more the industries are aggre- 
gated, but in this direction the meaning of an input-output 
framework diminishes too. So that input-output experts have 
always tried to find — so to speak — a sort of minimax point 
at which to stop the process of aggregation-disaggregation, in 
such a way as to keep the usefulness of an input-output table 
without making its coefficients too unstable. 
What has not been sufficiently realized is that the property 
of eliminating these shortcomings belongs to the completely 
aggregated quantities not because they are aggregated but be- 
cause — by being completely aggregated — they are necessarily 
vertically integrated. The property extends to all vertically 
integrated magnitudes as well. By resolving all products only 
into the same constituent original elements — labour and capi- 
tal — the vertically integrated approach leads to setting up rela- 
tions whose permanence over time does not depend on the dif- 
ferent technical possibilities. For example, two equivalent me- 
thods which, at a given point of time, entail the same cost for the 
same output, are represented in an inter-relation system by two 
different technical functions. But in a vertically integrated 
system, they are expressed by exactly the same function. Their 
being equivalent means that they require the same amount of 
10] Pasinetti - pag. 104