happens frequently we may refer to the problem as a system mis-
specification. The system needs to be recast so that it no longer
generates an error. Inherent, however in most systems are errors that
we tolerate because their ramifications are slight, or because
correcting the system may be over costly with respect to tolerating
the errors.
Systems can evolve and when they evolve to include undesirable
qualities that are very costly we do have to make an economic decision
as to whether the new errors are worth fixing. Such decisions can be
both economical and political, and require debate as well as
evaluation and much research.