From a design viewpoint, reinforcement requirements for exposed' and 'unexposed' slabs subjected to the same service moment differ luidely. TJiis points to an anomaly in current design criterion, which can be resolved by replacing the 'binary logic ' criterion with 'fuzzy logic ' criterion. The paper shows that this can be achieved by defining the concept of 'partial exposure' which facilitates a gradual transition from the 'exposed' to 'unexposed' conditions.