The relationship between trust and control is quite relevant both for the very notion of trust and for modelling and implementing trust-control relations with autonomous systems, but it is not trivial at all. On the one side, it is true that where/when there is control there is no trust, and vice versa. However, this refers to a restricted notion of trust : i.e., "trust in y," which is just a part, a component of the global trust needed for relying on the action of another agent. It is claimed that control is antagonistic of this strict form of trust; but also that it completes and complements it for arriving to a global trust. In other words, putting control and guarantees is trust-building; it produces a sufficient trust, when trust in y's autonomous willingness and competence would not be enough. It is also argued that control requires new forms of trust : trust in the control itself or in the controller, trust in y as for being monitored and controlled; trust in possible authorities, etc. Finally, it is shown that, paradoxically, control could not be antagonistic of strict trust in y, but it can even create and increase it by making y more willing or more effective. In conclusion, depending on the circumstances, control makes y more reliable or less reliable; control can either decrease or increase trust. Two kinds of control are also analyzed, characterized by two different functions : "pushing or influencing control" aimed at preventing violations or mistakes, versus "safety, correction, or adjustment control" aimed at preventing failure or damages after a violation or a mistake. A good theory of trust cannot be complete without a theory of control.
