D. M. MACKAY 
These same thrusts, if delivered earlier in the cycle, would 
quickly bring it to rest.) ‘The remedy here is to make the 
control respond partly to the rate of change of the mismatch (or 
even to gradient of rate of change) so as to “anticipate” the 
effects of sluggishness. 
On the other hand, the converse fault of hypersensitivity to 
rapid change can equally lead to instability, and can best be 
corrected by artificially increasing the “inertia”’ of the system. 
In either case, it is always possible to ease the problem by 
cutting down the overall sensitivity, reducing the strength of 
the correction evoked by a given degree of mismatch. This, 
however, achieves stability at the cost of a corresponding 
reduction in the precision of control. 
Although special (so-called ‘“‘linear’’) cases have been 
exhaustively treated mathematically, it is the qualitative 
recommendations of the theory which admit of most general 
application. These include (a) reduction of overall sensitivity to 
the minimum compatible with precision; (b) keeping the 
number of stages in the chain of informational control as small 
as possible; (c) making the control system sensitive to the 
rates of change of indications, and/or (conversely) to running 
averages, to combat respectively the effects of sluggishness or 
hypersensitivity to change; (d) arranging that any changes in 
the conditions against which the regulator is working (changes 
in supply, or demand, for example) are automatically “fed 
forward”? to set the control roughly in the right position. 
This leaves only the fine adjustment to be governed by the 
feedback of information. 
SELF-REGULATING SOCIAL MECHANISMS 
Having sampled the flavour of the new mechanics of 
informationally-organized systems, we may find it less absurd 
to ask in what respects it could affect our thinking about human 
society. One or two examples must here suffice. 
The first is drawn from the field of economics, where thinking 
along parallel lines was in fact initiated independently, notably 
by Keynes and his followers. In so far as it is possible to 
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