I think one important thing has been forgotten or dismissed in this discussion about collective (or social) control, namely the (source of) disturbance or the “common enemy”. I think that into the models should be added as one more “agent” the source of disturbance which its own gain and reference. Of course it is not a real controller but it can behave as if it were. I mean that the (virtual or not) controlled variable has some (stable or changing) value also when the real controllers are not controlling it and this value is as if the disturbances reference.
Here and there in the literature and discussions is mentioned “overwhelming disturbance”. In those cases the gain of the disturbance is (much) higher than the available gain of the controller.
For example if you control for a stone to be 1,5 meters above the ground but the stone is too heave and you can lift it only a few centimeters, then the disturbance’s (gravity’s) “reference” is 0 meters and its gain is quite overwhelmingly greater that yours. As a consequence your error is high. But now there comes a friend who happens to control for the same stone to be 1 meter above the ground. You and your friend have conflicting references but together you may be able to lift it at least to that 1 one meter and perhaps even some centimeters above it. Now in spite of your conflict you control much better than you would alone and thus without a conflict. In this case the conflict is beneficial for the controllers because the “conflict” with the disturbance can be at least partially solved by the conflictual collective control.
So there is no strict and fixed borderline between collaborative and conflictual collective control but it depends on conditions. Because of our individual differences which Warren mentioned it seems quite improbable that in any collaboration all participants would have exactly same controlled variables and exactly same references for them. Instead there is always also a lesser or greater conflict. But in any case the control tends to create stabilities which in happy cases are more or less beneficial to all or most participants – even if no one were absolutely satisfied.
Eetu