Realism in International Relations

Realism in International Relations

In this article, we shall discuss the theory of realism as it relates to international relations. We will discuss the assumptions of realism, some of the main beliefs by realists, as well as any disagreements between realists. 

Realism in international relations or what is also referred to as Political Realism, is seen as “one of the oldest theories to international relations, and is widely held as a worldview” (Pease, 2012: 43). While it is one of the earliest theories, “[t]he first coherent expressions of a realist approach to the study of international politics evolved out of the apparent failure of liberal principles to the international sphere would change the nature of global politics, in particular its endemic violence” (Burchill, 2001: 71).

Realist theorists argue that politics should viewed as it currently exists, and not how one would wish the world were. And when looking at the political system, or more specifically, the international system, realists focus their ideas about how international relations work based upon the concepts of power and security. 

While there are variations amongst realists, there are a number of assumptions that realists make regarding the international system, assumptions which can be compared to other theories such as liberalism, constructivism, and feminism.

Realism in international relations is largely centered on realist assumptions of human behavior. The realists believe that human behavior is often related concerns about ego and individual passions and desires, and more specifically, the presence of evil in human beings. They believe that given the conditions of the world, humans themselves, if left to do what they could, would carry out evil actions against others. As Donnelly writes (2000), “realists characteristically give primary emphasis to egoistic passions and “the tragic presence of evil in all political action” (Morgenthau, 1946: 203). And because these passions are ineradicable, “conflict is inevitable” (Niebuhr 1932: xv). “It is profitless to imagine a hypothetical world in which men no longer organize themselves in groups for purposes of conflict” (Carr 1946: 231). Donnelly continues by saying that “Whatever their other disagreements, realists are unanimous in holding that human nature contains an ineradicable core of egoistic passions; that these passions define the central problem of politics; that the statesmanship is dominated by the need to control this side of human nature” (10).

Kelly-Kate S. Pease (2012) lays out four primary assumptions of realism related to the study of international relations. They are as follows:

1). “The state is the most important actor in international relations” (48). As she explained, realists see the system as a state dominated one. This has been the position since 1648, during the Treaty of Westphalia or the Peace of Westphalia), where a number of European powers came together to end various wars (such as the 30 Years War). In this meeting, they agreed to the idea of state-sovereignty, where no outside actor can dictate the domestic or foreign policies of another state (although realists see the principle of sovereignty being only as good as the physical ability to protect one’s sovereignty) (Pease, 2012). And ever since the Treaty of Westphalia/Peace of Westphalia, many in the realist camp have argued that states, due to their military and economic power (through weapons, finances), have the most influence in international relations.

But along with the assumption that the political state is the most powerful actor, realists in turn also give  little weight is given to non-state actors. They view individuals and non-government organizations as lacking the military power needed to compete with states in the international system.

2). A second assumption of realism that many realists (at least traditional realists) believe is that “The state is a unitary and rational actor” (48). While realists know many actors technically exist, “all of these differing views are ultimately integrated through state structures so that the state speaks with one voice (Viotti & Kauppi, 1993; 35, in Pease, 2012: 48). Pease (2012) goes on to explain that “…that single voice speaks for a rational state–a single actor capable of identifying goals and preferences and determining their relative importance. The state is also capable of engaging in a cost-benefit analysis and choosing optimal strategies for achieving its goals” (48). And because of the belief that states are unitary, internal differences are not nearly as important as the state. This is why foreign policy is given significant attention in realist political thought. They argue that regardless of any internal differences, the unified position will be one that is of the interest of the state.

3). The third assumption Pease cites for realism/political realism is the idea that “international relations are essentially conflictual” (49). All realists seem to say that the international system is one of tension and conflict. Now, the reasons as to why this is vary; some think it is due to the “pessimistic” view of human nature, whereas others think it has to do more with the structure of the international system. Nevertheless, various positions congregate on this point of conflict in international relations.

One of the reasons that some structural realists see the system as one that leads to conflict has to do with the notion of anarchy. As we know, the world is an anarchical system. This means that there is no overarching power controlling the behavior of actors within the state system. And because the system is in anarchy, states must be on the lookout for themselves against other states, since a state is primarily concerned with achieving political power. Realists call this a “self-help system” where “one nation’s search for security often leaves its current and potential advisories insecure, any nation that strives for absolute security leaves all others in the system absolutely insecure, and it can provide a powerful incentive for arms races and other types of hostile interactions” (Holsti, 1985:

4). Realists thus view the system as one that leads to a competition for power, where a state’s objective is security and power.

And as Pease (2012) explains, “Anarchy compels sates to arm themselves to self-defense. However, the acquisition of arms is itself a provocative act. Other states must respond in kind or risk attack or destruction. This response leaves the first state no better off that it was before, so it must acquire even better weapons to counter the threat. Then the other states must respond in kind. And so on. Anarchy leads to arms-racing and arms-balancing behavior on the part of states. States with good and kind leaders will engage in the same kind of behavior as selfish and evil leaders because they exist in the same international environment” (49). Thus, to realists, or more specifically, neo-realists, the anarchical system forces states to be concerned with issues of power in order to survive (Slaughter, 722).

However, this idea of power imbalance is not merely limited to military power; economic power also enters into the equation. States whose economies is growing are also gaining power, since economic strength often translates to power in the international system. Thus, realists, and in particular neo-realists, also pay attention to a states economy as it relates to power. 

Given these points, for realists, states will try to accumulate power. And when there is a power imbalance, the likelihood of war is more possible, since the power powerful state can attack a weaker state, without much penalty, if any at all. Thus, for realists, it is the balance of power as a system that will prevent wars; states that are balanced would be less likely to attack and fight one another. Realism in international relations is in fact centered on this importance of power.

However, there are disagreements between realists as to the reason for power. As Walt (1998) explains: “the most interesting conceptual development within the realist paradigm has been the emerging split between the “defensive” and “offensive” strands of thought. Defensive realists such as Waltz, Van Evera, and Jack Snyder assumed that states had little intrinsic interest in military conquest and argued that the costs of expansion generally outweighed the benefits. Accordingly, they maintained that great power wars occurred largely because domestic groups fostered exaggerated perceptions of threat and an excessive faith in the efficacy of military force” (37). However, “offensive” realists have challenged this idea, citing many cases that they argue has went against this theory proposed by “defensive” realism. Moreover, these offensive realists continue to look to the effects of anarchy on ideas of gaining as much power as is possible given the uncertainties of the international system (Walt, 1998).

Relative vs. Absolute Power

Further, for realists, another point about power is realists see it as relative power, as opposed to absolute power. Thus, for realists, if two states enter into a trade agreement, but that agreement helps one states economy more than the other, even though both gain power, the weaker state should still be skeptical, since there is a relative power compared to the stronger state. The stronger state still could attack the weaker state. Thus, tot only does it matter how much power the state has, but it must also be in the context of how powerful another state is. Thus, a military or economic deal that benefits both states may not be as appealing to the one state if the relative power is not clearly in its advantage. And many realists would urge a state to be careful into making such agreements if they are losing relative power compared to the other state.

4). “Security and geostrategic issues, or high politics, dominate the international agenda” (50). While there are scores upon scores of international issues that states can focus and work on, the ones that receive the most attention are those that relate to national security. A state’s primary objective is to survival, whereas for some classical realists, it can go as far as “world domination.” Thus, issues that don’t pertain to security are viewed as far less important by realists.

According to Ann-Marie Slaughter

This vision of the world [for realists] rests on four assumptions (Mearsheimer 1994). First, Realists claim that survival is the principal goal of every State. Foreign invasion and occupation are thus the most pressing threats that any State faces. Even if domestic interests, strategic culture, or commitment to a set of national ideals would dictate more benevolent or co- operative international goals, the anarchy of the international system requires that States constantly ensure that they have sufficient power to defend themselves and advance their material interests necessary for survival. Second, Realists hold States to be rational actors. This means that, given the goal of survival, States will act as best they can in order to maximize their likelihood of continuing to exist. Third, Realists assume that all States possess some military capacity, and no State knows what its neighbors intend precisely. The world, in other words, is dangerous and uncertain. Fourth, in such a world it is the Great Powers—the States with most economic clout and, especially, military might, that are decisive. In this view international relations is essentially a story of Great Power politics.

Thus, in realism there has been a focus on military and economic strength since such resources often translate to increased power in the international system.


The theory of realism is not unified in its approach to international politics. There have been (and still are) variations of the theory. Now, there are some commonalities amongst realists; “Realists are unified in their pessimism about the extent to which the international political system can be made more peaceful and just. The international realm is characterized by conflict , suspicion and competition between nation-states, a logic which thwarts the realization of alternative world orders” (Burchill, 2001: 70).

However, one of the main difference between realism and neo-realism has to do with the reason for state behavior. More traditional realists focused on the internal state’s behavior as the reason. However, others, such as Kenneth Waltz, who has contributed greatly to neo-realism, focus more on the world system and the ways the system limits or dictates behavior. So it is not about the behavior of the individual as it is about the importance of anarchy; anarchy is the reason that states act the way that they do (Burchill, 2001).


I have listed a number of very important books on the topic of realism below that will hopefully help students and scholars as they read on international relations theory. These works are by both realists as well as neorealists. As we see, realism in international relations is one of the most noted theories, and has various assumptions associated with the theory.


Hans Morgenthau: Politics Among Nations

Kenneth Waltz: Theory of International Relations

Kenneth Waltz: Man, the State, and War: A Theoretical Analysis




Burchill, S. et. al. (2001). Theories of International Relations, 2nd edition. New York, New York. Palgrave Macmillan

Donnelly, J. (2000). Realism and International Relations. Cambridge, England. Cambridge University Press.

Holsti, O.R. (1985). Theories in International Relations, in the Dividing Discipline: Hegemony and Diversity in International Theory. Available Online:

Slaughter, A.M. (1995). Liberal International Relations Theory and International Economic Law. American University International Law Review, Vol. 10, No. 2, pages 717-743.

Slaughter, A.M. (2011). International Relations, Principal Theories. Available Online:

Walt, S. (1998). International Relations: One World, Many Theories. Foreign Policy, Spring 1998, No. 110, pages 29-46.

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