In international relations, a variety of perspectives have evolved from the need to explain the motives of international actors and possibly predict future actions. The perspectives are used by political scientists to understand how the international world works. Two of these perspectives are constructivism and realism. Realism is usually considered the central framework used in analysing international relations, while constructivism is considered an alternative approach.
Power is one of the key concepts of international political thinking. Power, according to Joshua Goldstein and Jon Pevehouse, is being able to convince another person or entity to do something they would normally not have done. This ability is essentially what all international actors want to have: the ability to convince another actor to either do or not do something. This definition of power colours the way various frameworks for analysing international relations function.
Realists have a generally pessimistic outlook about human nature and how actors use power. They believe that humans, and therefore actors, are naturally selfish and are constantly searching for ways to get what they want, without regard for the needs of others. Most realists refer to this as the pursuit of self-interests. Power is key for realists, as whoever has the power gets what they desire. The most important actor in the international community for realists is the state. Realism relies on the belief that no true international governing bodies exist. Realists look at actions and look for the consequences.
Constructivists take the idea of a state acting in its own self-interest and go a step further. This method focuses on the social relations of actors between each other and within themselves to understand what an actor wants to gain from a given situation and how the relationship might affect these desires. Constructivism also looks at social norms, or how actors should behave in a given situation. This differs greatly from the realist perspective of analysing the consequences of an action. For constructivists, having power isn't the main goal; following societal norms is.
Realists and Constructivists differ mainly on the motivations of actors' actions. Realists believe all actors are motivated by a need for power, while Constructivists believe that actors are guided by their interpretation of societal norms. These motivations are key for understanding and predicting how the international world operates and are the basis for theories of international relations.