When is the economic theory useless?

One misunderstanding is to under-estimate the role of an economic theory. Several people thought an economic theory useless since they think assumptions imposed into the theory are unrealistic. Actually, no theory, whether in physics, economics or any other science, is completely accurate. The validity of a theory based on whether or not this succeeds in explaining and predicting the set of phenomena which this is intended to describe and predict. Therefore theories are incessantly tested against observations. Like a result of this testing, they are frequently modified, refined, and even discarded.