Thanks to Powerline for a nice overview of realism a it applies to international relations. However, I fear that this notion of political science has a common flaw: the assignment of inappropriate attributes to collective groups. I don’t believe that nations have interests or even that nations can have interests. Instead, those individuals in power have interests. Now it might be true that anyone in power in a given nation might share the some of the same interests. It is certainly tempting to view those shared interests as national interests. But that kind of thinking can lead to flawed analysis. These flaws can be avoided by remembering that only individuals can have goals. When groups of people have a common goal, the goal is usually a fragile compromise among individuals. A more accurate portrayal of systems comes from always viewing composite goals, interests, and actions as the result of individual components from which an order has emerged.