1. A method of acquiring fuzzy knowledge in order to define and edit a membership function representing a fuzzy set, said method comprising the steps of: (a) pointing to a parameter position to be defined from said membership function by applying a pointing device to said membership function displayed on a display device; (b) plotting parameter positions pointed to by said pointing device to form a graphic shape of said membership function; (c) obtaining a progress position of said pointing device during said plotting of said membership function graphic shape; (d) converting said progress position into a parameter value of said membership function; (e) storing said parameter value of said membership function; (f) plotting an updated graphic shape of said membership function on said display device in accordance with said stored parameter value to form an updated graphic shape of said membership function; (g) displaying said updated graphic shape of said membership function on said display device; (h) pointing to an updated parameter position to be defined from said displayed updated membership function by applying said pointing device to said membership function displayed on said display device; (i) repeating steps (c) through (h) in order to alter a defined parameter value most proximate to said original parameter value to be defined.