In a dialogue system for a motor vehicle, the dialogue system including a plurality of control keys, assigning a function from a predefined set of functions to at least one of the control keys in such a manner that the function is executed upon actuation of the control key. At least one of the functions which can be assigned to the control key is configured as the master function. During the execution of the master function the current value of at least one parameter of a subordinate function that correlates with at least one state of the motor vehicle is determined, and the subordinate function is executed as a function of this value.