The international system or the state: What is the source of Turkey's national interest

This study examines the concept of national interest, which is defined as a guide that directs the foreign policy behaviors of states, at the level of the international system. The study basically claims that the stability and instability processes of the international system in a cyclical process are the main source that determines the interests of the nations. According to this claim, the international structure and order, which are the components of the stable international system, will build a certainty on the interests and behaviors of the states in the system. In other words, it can be assumed that the dominance of international systemic forces will shape or constrain the decision-making processes of states. Conversely, unstable international systems can be defined as periods that there is a high degree of uncertainty in world politics due to challenges to the established international structure and order. In such periods, it can be stated that systemic uncertainties will alleviate the pressure on states, and thus, the power capacities of states will be the main factor to determine the source of national interests. In this context, the thesis is basically divided into three parts. First, the literature review reveals other alternative approaches that can be considered as a source of national interest. The second part, on the other hand, discusses the stable and unstable periods of the international system, which is the main subject of the thesis, and explores how and in what way these periods affect the national interests of the states. The third part of the thesis examines the Turkish foreign policy from 1999 to 2020 and exhibits the role of two distinct periods of the international system in determining the interests of nations. Keywords: Instability, International System, National Interest, Stability, Turkish Foreign Policy