1. A method of controlling a tracking of a head relative to a medium from which signals are played back comprising a steps of: detecting a signal level of signals which are played back; generating present tracking control direction and magnitude values as a function of the detected signal level by providing a first set of membership functions representing respective degrees to which changes in the detected signal level satisfy predetermined ranges of change, providing a second set of membership functions representing respective degrees to which previous tracking control direction and magnitude adjustments satisfy predetermined ranges of adjustment, determining particular membership functions from said first and second sets corresponding to a detected signal level change and to a preceding tracking control direction and magnitude adjustment, and inferring said present tracking control direction and magnitude values from the determined membership functions; and adjusting the tracking of said head in response to the present tracking control value.