What has Cybernetics to do with Operational Research?

Part 1 of this paper answers the question "What is cybernetics?" A brief historical review introduces a somewhat formal statement about the nature of systems and the way they are controlled. The unifying topic in the study of control in every context is an underlying identity of system: an example is taken from learning machines.A comparably brief treatment of the question "What is operational research?" is given in Part 2. Operational research is thought to be the latest exemplification of scientific method rather than "a science". What is important about operational research is brought out through a description of an actual case study, and some of the activities which look like operational research but are not are mentioned. This leads to an attempted definition of operational research.Part 3 tries to draw the answers to the first two questions together, and to show how operational research and cybernetics are related. It is possible to pursue each activity in its own right; but it is also possible to practise operational research with essentially cybernetic models, and to study cybernetics by operational research techniques. This thought is generalized into the idea that cybernetics is the science of which operational research is the method.