15. The reasoning with uncertainty system of claim 14 wherein said control portion selects each said T-norm function T.sub.i for use by said inference portion in computing said premise certainty and conclusion detachment intervals; each said T-norm function T.sub.i corresponding to a different attitude toward uncertainty evaluation such that: the T-norm function T.sub.1 corresponds to a conservative attitude toward uncertainty evaluation; the T-norm function T.sub.2 corresponds to an intermediate attitude toward uncertainty evaluation; and the T-norm function T.sub.3 corresponds to a nonconservative attitude toward uncertainty evaluation.
14. The reasoning with uncertainty system of claim 10 wherein said value certainty, premise certainty and conclusion detachment intervals are defined on an interval [0,1.0]; said inference portion computing said premise certainty interval in accordance with the equation: EQU [b,B]=[T.sub.i (a.sub.1,a.sub.2, . . . ,a.sub.m),T.sub.i (A.sub.1,A.sub.2, . . . ,A.sub.m)] where: [b,B] is said premise certainty interval; [a.sub.1,A.sub.1 ], [a.sub.2,A.sub.2 ], . . . ,[a.sub.m,A.sub.m ] are m said value certainty intervals associated with the values assigned to the premise variables; and T.sub.i is a triangular norm (T-norm) function selected from a first function set comprising the predetermined T-norm functions T.sub.1, T.sub.2 and T.sub.3 ; and said inference portion computing said conclusion detachment interval in accordance with the equation: EQU [c,C]=[T.sub.i (s,b),N(T.sub.i (n,N(B)))] where: [c,C] is said conclusion detachment interval; T.sub.i is the T-norm function selected from said first function set; s is said rule sufficiency factor; n is said rule necessity factor; [b,B] is said premise certainty interval; and N is a negation operator such that N(.alpha.)=1-.alpha..