It is rather obvious that different developments in the international relations scene are so dynamic that a theory of international relations cannot elaborate alone the ways they begin, develop and eventually end. Therefore, one must underline that using a theoretical framework of wi-der extent becomes almost indispensable. In this sense, one must underli-ne that IR theories are paths or means used by scholars to provide expla-nation on these developments. Among numerous IR theories, those app-lied the most are the three key ones: liberalism, realism and rationalism.These three theories, depending on the manner and logic of approach and effort in trying to elaborate an IR event, they gain labels in a specific form, for instance – positivist theories. They are called positivist, because they aim to pursue the example of natural science to be more accurate in their work, at least in a metaphorical sense. Therefore, the contents of this paper provide an example of physics, to adapt to the nature of theory elaborated herein.The reason and objective of this paper is to argue our thesis that “li-beral theory alone cannot elaborate on all IR developments, and more theories are required”. The two other theories, realism and ratio-nalism help build a more wholesome understanding of IR developments. Also, the two other theories are used to support or counter the arguments of liberals and liberalism in relation to interpretation, explication and forecast of IR developments, which are tasks of an IR theory.This research is realized in a temporal context of post Cold War. This period is more suitable for study, and has attracted our interest. Otherwise, the three theoretical traditions had existed even before, and any effort to elaborate in details would be historical. Also, the focus in only three main IR theories, Liberalism, Realism and Rationalism, narrow down the field of study and make it more tangible. Nevertheless, to have an easier job in reaching a scientific and statistically measurable scientific conclusion, we have analysed only the views of authors consi-dered to be the key representatives of the three main theories. Hence, only in a narrow context of time, theory and author, can we reach more accurate con-clusions. For the purposes of this paper, Fukuyama is the “Liberalist”, Huntington is “Realist” and Brzezinski is a “Rationalist”.
Why a developmental perspective is critical for understanding human cognition
