1. A method of evaluating a confidence in an outcome of a fuzzy logic possibilistic system comprising the steps of providing a rule that maps a given input to a predictable output; selecting a plurality of inputs that differ from said given output; establishing a relationship between said given input and said selected inputs; assigning a degree of possibility to possible outcomes resulting from application of said selected ones of inputs to said rule; said degree of possibility being correlated to said relationship established between said given input and said selected input; establishing an envelope of possibility that encompasses each of said possible outcomes resulting from said selected inputs; according to each of said selected inputs a credibility to establish an envelope of belief within said envelope of possibility; comparing said envelope of belief and said envelope of possibility; and determining confidence in an indicated outcome based on difference between said envelopes.