1. A fuzzy inference apparatus comprising: a storage device for storing, prior to the use of said apparatus, rules defining relationships between phenomenon and a plurality of conclusions; a device for supplying input data; a fuzzy inference device coupled to said storage device which performs fuzzy inferences to calculate, as an output, the possibility of a conclusion by applying at least one of said stored rules to said input data; a calculating device coupled to said storage device for calculating at least one of a static information amount and a clearness for each said phenomenon with respect to each respective conclusion using at least one of said stored rules, said static information amount indicating the degree to which a membership function for a phenomenon has a discriminable conclusion, said clearness indicating the relative discrimination ability of each phenomenon at the time a possibility of a conclusion is assessed; and a display device for displaying at least one of said static information amount and said clearness for a particular conclusion; wherein said fuzzy inference device includes: a grade calculating device which optimizes a grade using a membership function which expresses said input data in terms of said rules; a dynamic information calculating device for determining a dynamic information amount of each said phenomenon using said grade, said dynamic information amount indicating the discriminating power a phenomenon possess with regard to deciding on a single conclusion when an inference is made; and a possibility calculating device which determines the possibility of a conclusion using at least one grade and said dynamic information amount.