All of the Soft Computing Models have shown limited success in dealing with the problems of Intelligent Decision Making where system modelling is difficult and limited operational data is available. The situation is further aggravated when decision making has to be fast, as in the case of Complex System Fault Diagnosis. Computational Theory of Perceptions has proved to be useful in dealing with such situations. Perception is a powerful mental process for knowledge acquisition from sensed data. The strength of perception lies in the fact that it is capable of representing the knowledge contained in information in a more subtle manner as compared to measurement, which quantifies it mathematically with attendant limitations and approximations.The use of perception based knowledge for operation and control of complex systems paves the way for implementation of Epistemological Decision Making. The aim of Epistemological Decision Making is to arrive at rational decisions based not only on merely numerical data but also on the conceptual knowledge contained in the data.