The first principle of wing walking establishes that we should not abandon one theory for another until the new theory proves to be a better tool for explaining the events of interest. The reliability of predictions is the primary standard for judging the relative merits of com¬peting explanations of events. Theories provide the linkage between assumptions and empirical generalizations. They stipulate how variables relate to one another. In doing so, theories identify the causal or probabilistic association between independent and dependent variables. They provide a simplified view of reality that is believed to reduce the complexity of the real world to its essential components.

Assumptions describe the set of conditions under which a theory is expected to apply to the phenomena of interest. Hence, assumptions define a theory’s relevant world of applicability. If the assumed world is too far removed from the world in which we live, then the theory’s predictions will prove unreliable and we will conclude that the theory is useless or trivial. If the assumptions contradict one another on logical grounds, then the theory is logically false and so cannot provide a coherent explanation of the world in which we live. Consequently, theories are judged based on their logical consistency and empirical usefulness. Taste or aes¬thetic appeal are not relevant in evaluating alternative explanations of international affairs; adherence to the requirements of the scientific method is critical.