10. A fuzzy inference apparatus comprising: an input device for entering input data related to phenomena; a storage device for storing knowledge of expert users expressing relationships between phenomena and conclusions as a plurality of membership functions, wherein said relationships include various multiple phenomena about which a single conclusion is to be drawn conjoined in an OR relationship and also include multiple phenomena and conclusions conjoined in an AND relationship; a grade calculating device for determining a grade measure for said input data with respect to each of said plurality of membership functions, for determining a first grade for a group of phenomena conjoined in an OR relationship, and for determining a second grade for another group of phenomena conjoined in an AND relationship; a fuzzy information amount calculating device for calculating the fuzzy information amount for each phenomenon using said grade measures; and a possibility calculating device for calculating the possibility of a conclusion using said grade measures, said first grade, said second grade and said fuzzy information amounts.
10. A fuzzy inference apparatus comprising: an input device for entering input data related to phenomena; a storage device for storing knowledge of expert users expressing relationships between phenomena and conclusions as a plurality of membership functions, wherein said relationships include various multiple phenomena about which a single conclusion is to be drawn conjoined in an OR relationship and also include multiple phenomena and conclusions conjoined in an AND relationship; a grade calculating device for determining a grade measure for said input data with respect to each of said plurality of membership functions, for determining a first grade for a group of phenomena conjoined in an OR relationship, and for determining a second grade for another group of phenomena conjoined in an AND relationship; a fuzzy information amount calculating device for calculating the fuzzy information amount for each phenomenon using said grade measures; and a possibility calculating device for calculating the possibility of a conclusion using said grade measures, said first grade, said second grade and said fuzzy information amounts. 13. The fuzzy inference apparatus of claim 10, further comprising a clearness device which comprises: a static information amount calculating device for calculating a static information amount for each phenomenon based on said membership functions; a clearness calculating device for calculating the clearness of each phenomenon with respect to each conclusion using said static information amounts; and an adding device for calculating a clearness of each said conclusion by adding together said clearnesses of said phenomena relating to said input data for a given conclusion; and a clearness storage device for storing the clearness calculation.