Especially in times of international conflicts, it is customary that politicians refer to “the national interest” as a justification for their actions beyond the state borders, commonly named foreign policy. There is a huge literature on the subject, in which the concept of the national interest is useful, (1) because it suggests some higher ranking political goal, (2) because it clarifies and prioritizes a country’s goals, particularly at times of military interventions and (3) because it “arouses the support necessary to move towards a realization of the goals” (Rosenau 1968, Int. Encycl. p.34).
A critical assessment of this concept in international relations should start with the democratic perspective that a country’s government is subject to regular elections, whereby the goals a previous majority had put forward, might substantially change as a new majority takes the lead. Continuation of the same foreign policies is not excluded, but at least subject to revision. In authoritarian regimes the definition of the national interest is probably more stable, because authoritarian leadership does not hesitate to define the national interest in “splendid isolation” from its people.
Overall, the concept appears to serve mainly communication purposes, both internally as well as towards the outside as in communicable foreign policy goals. Conflicts between countries can thus be named and become subject to diplomacy and international treaties. But we have to fill this with substance over and over again as new topics arise like climate change and global warming.
