Theories can at best be classified into three, a) Grand Theory, b) Middle range theory and c) Supposition theory. Grand theories are comprehensive and have wide application over a variety of settings. However, the concepts are extremely abstract and not operationally defined and are not testable. As an extreme we have the supposition theory, which is too parochial and narrow in its approach, and tends to oversimplify the reality to adjust the needs of research. For instance, these studies could be linked to special populations or an identified field of practice and concrete concepts, which are already operational and well tested. We must avoid the temptation of both the extremes to choose something called middle range theory, which is based on superior suppositions, keeping in mind its testability.
By Shankar MM