by Liu Feng and Zhang Ruizhuang
Much more than a single theory, realism is a school of thought containing numerous related branches. In recent years an outpour of debate and exchange within the realist tradition has captured the attention of scholars. Many scholars have attempted to create schemes classifying the different branches and threads of realist thought that have emerged, while others have introduced a wealth of new terminology. Unfortunately, as a result of these efforts, realist concepts have become obfuscated, resulting in much confusion, and ultimately erecting a barrier to intellectual progress in the field. The goal of this article is to help remove this barrier by clarifying the criteria for classifying different approaches to realist thought and presenting a more coherent classification scheme that will enhance the understanding of the relationship between various strands of realist thought.
The Debate Regarding the Classification of Type of Realism
Since the 1980s, a number of new schools of thought, including constructivism, critical theory and post-modernism, have critiqued, and ultimately come to challenge, traditional schools of international relations theory such as realism and liberalism. Yet, as a result of sharp differences with respect to ontology, epistemology and methodology, exchange between these new schools and the more traditional mainstream schools have been quite limited. In stark contrast with this dearth of scholarly exchange across schools of thought, the intellectual debate and exchange of ideas within the realist school have flowered, giving birth to many new branches and sub-branches of realist thought.
Against the backdrop of this debate within the realist school, comparison and analysis of its different branches have moved to the forefront of research in international relations. The attention given to this debate by scholars across the world has deepened research on realism. These researches have dealt with developing the logic of the new strands of thought, testing them empirically, comparing them, or studying the relationship between new strands and traditional realism or structural realism. In broader terms, some researches have also focused on investigating the implications of this debate for the overall influence of realism on the discipline of international relations, especially with respect to whether the evolution of realist thought represents a step forward or a step backward with respect to our understanding of international relations.
But while this debate has contributed to the accumulation of knowledge and to intellectual progress, more recent research on this debate also demonstrates that it has also lead to the obfuscation of many concepts, and has created much confusion between scholars. Scholars have different focal points in their research, and different views on how to classify and understand the relationship between these new branches. This has lead to many attempts to restate viewpoints and assumptions, and to introduce many new concepts in order to clarify different theories. As Glen Snyder points out, there are now, in the field of contemporary international relations, at least two types of structural realism; potentially three types of offensive realism, not to mention numerous brands of defensive realism. In addition, there is neo-classical realism, contingent realism, specific realism, general realism and numerous other realisms. Michael Doyle, in his attempt to synthesize the intellectual history of international relations, further finds four distinct traditions within realism: Thucydides’ complex realism, Machiavelli's fundamentalist realism, Hobbes’ structural realism and Rousseau's constitutional realism. Doyle further argues that later development of realism was divided into these four different traditions of political thought.
On the one hand, that there are so many different strands of realist thought reflects the tremendous amount of disagreement between scholars working within the realist school. Yet on the other, this is also indicative of some difficulties and misconceptions that are held by various realist scholars, particularly with respect to how to identify and classify the different strands of realism. From the perspective of maintaining theoretical coherency, casually assigning labels tends to obscure the connection between different theories, exaggerating differences between different branches of theory. By introducing many concepts that are really not necessary, learning and understanding the theories become increasingly difficult. As a result, creating a scientific, coherent classification of the many branches of thought that have poured out of the realist camp stands to aid in clarifying and increasing understanding of this important school of international relations theory. In addition, as the different strands of realism are much more amenable to comparison with one another than with comparisons across different schools of IR theory, clarifying concepts and breaking down barriers stands to improve a dialogue between realists that stands to generate much progress in the field.
There are several established criteria for classifying theories within a mature school of thought in international relations. It is possible to group theories with respect to their central theoretical concept, their main assumptions or according to the units of analysis employed in the theory. For example, classifying according to main assumptions and general themes, it is generally held that the liberalist school can be divided into republican liberalism, economic liberalism, cognitive liberalism, social liberalism and institutional liberalism. Constructivism can be divided into identity-centred constructivism, norm-centred constructivism, and speech-act-oriented constructivism when classifying according to core theoretical concepts. Using units of analysis, Kenneth Waltz divides international relations theory into three images: that of man, state and system. Although Waltz's classification is rather broad—so much that it goes beyond any single intellectual tradition in international relations, a similar type of classification could be made for any given theoretical school.
In contrast to the clarity and precision associated with the classifications used in other schools of IR thought, the classifications that scholars have used for the realist school are vague and imprecise. Take for example, John Mearsheimer's attempt to distinguish between the three different branches of realism: human nature realism, offensive realism and defensive realism. Human nature realism can be seen as distinct in terms of its theoretical assumptions, or in terms of its units of analysis, yet offensive and defensive realism are distinguished in terms of an assumption with respect to states’ demands for power. Such a classification obviously lacks a unifying criterion linking the three branches together. According to the criterion that Mearsheimer uses with respect to states’ demand for power, Morgenthau's classical (human nature) realism should be classified as offensive realism, as Morgenthau contends that states seek to maximize their power. On the other hand, when employing level of analysis as the main criterion, both Mearsheimer's offensive realism and Waltz's defensive realism should be classified as structural realism, as both emphasize the international system and its structural restrictions on the behaviour of states.
The classifications used by other scholars are obviously also a source of misunderstanding in the discipline. For example, Stephen Brooks divides modern realism into neo-realism and post-classical realism, while Gideon Rose uses the categories neo-realism and neo-classical realism. The terminology used by these two scholars are very similar, so much so that without careful attention to the way that these scholars use these terms, one might conclude that Brooks and Gideon's typologies are analogous. In reality though, their classifications could not be more different. Brooks uses ‘post-classical realism’ to refer to defensive realism, while he uses the term ‘neo-realism,’ for which scholars already have a generally accepted definition, to describe the entirely different notion of offensive realism. Rose on the other hand uses neo-classical realism to represent scholarship that emphasizes the domestic level of analysis.
As is readily apparent from the above discussion, using different or inconsistent criteria to classify branches of theory, or inconsistent terminology can create misunderstandings which adversely affect scholarly debate. It is necessary to carefully consider the different classifications of realism, clarify the standards that should be used to create such classifications and proceed by establishing a coherent classification system. Through the synthesis of realist scholarship, this article identifies and discusses four dimensions according to which realist theories should be classified and through analysis of the current classification systems employed, it further clarifies the criteria that should be employed for consistently classifying branches of realist thought.
As we will argue below, unit of analysis and types of independent variables, dependent variables and theoretical assumptions are the best criteria to use when constructing a typology of realism. Using the first of these criteria (unit of analysis and independent variables), we show that realist thought can be divided into three branches: human nature realism, state-centric realism and system-centric realism. Using the second, dependent variables, we identify two broad categories of phenomena that theories of realism attempt to explain: theory of international politics and theory of foreign policy. Associated with this first category is structural realism, while neo-classical realism's focus is on the latter. Introducing the third of our criteria, theoretical assumptions, a major distinction is identified with respect to assumptions regarding whether countries seek security or power. These assumptions point to an important division within both structural realism and neo-classical realism: that between defensive and offensive realism. Finally, one additional classification can be made with respect to theoretical assumptions. As there are different understandings within realism with respect to the nature of the international system, a distinction can be made between balance of power realism and hegemonic realism. We argue, however, that this distinction should not be a basis for classifying types of realism, and that a consistent typology should limit itself to the preceding three dimensions.
This article turns next to introducing each of these criteria for classifying realist theories, and discussing each of the branches identified above. It also discusses linkages between the different criteria and addresses the coherency of this type of classification.
Man, State and System : Three Images of Realism
In Kenneth Waltz's classic, Man, the State and War, Waltz shows that all of the various explanations for the causes of war can be easily filtered into three images: that of man, the state and the international system. While Waltz was less concerned with creating a typology, and more interested in making progress with respect to understanding the reasons for the causes of war, his work demonstrates the power of classifying theories with respect to units of analysis. The selection of a particular unit of analysis reflects a core concern of theory building: the selection of the independent variable. The unit of analysis reflects to a great degree the independent variable that is selected in the theorization of a particular casual relationship. As the purpose of theory is to explain a casual relationship and describe a casual mechanism using the casual variables, it is natural that the unit of analysis be the starting point for a classification of realist theories.
Applying Waltz's logic to the realist camp, distinct categories of explanations can be readily identified. For example, traditional realism, with its emphasis on individuals, explains international phenomena and state behaviour from the point of view that human nature is intrinsically evil. Structural realism on the other hand throws out this assumption, and conducts an analysis based on the objective nature of the international structure, a system-level analysis. From the perspective of units of analysis, the different casual stories told by realist thinkers can be divided into three distinct categories: human nature realism, state-centric realism and system-centric realism.
Human nature realism, also known as biological realism, emphasizes man's biological abilities and intrinsically evil nature. Most classical realists (including the many modern political philosophers who have contributed to the development of realist thought), including especially Machiavelli, Herbert Butterfield, Reinhold Niebuhr, and Hans Morgenthau fall into this category. Morgenthau's theory is the best example of human nature realism in international relations. In Politics Among Nations, Morgenthau presents a systematic discussion of the basic principles of realism. The first of these principles consists of an assumption regarding the role of human nature in politics: politics ‘is governed by the objective laws that have their root in human nature.’ In Morgenthau's view, ‘political man is a selfish animal, and all human behaviour tends towards the control of others.’ As a result, battles over power are rooted in human nature and as such are central to politics.
State-centric realism looks for explanations for international relations phenomena and state behaviour from the vantage point of individual states (including national attributes, national interests and domestic politics). It is generally thought that realism does not concern domestic aspects of politics, or that consideration of such domestic issues represents a step away from realism's core concerns. This type of view though represents an obvious misunderstanding of realism. A careful look at the origins of realism, before Waltz's theory of international political systems, shows that most theorists in the realist camp focused their efforts on the level of the individual or of the state. Gilpin, for example, refers to himself as a state-centric realist scholar. In the field of international political economy, he contends that state interests and policies hinge on the governing political elite, on the pressures of powerful groups within a national society and on the nature of the ‘national system of political economy’. The neo-classical realism that has been popularized more recently argues even more explicitly that individual states should be integrated into the theories of foreign policy. Scholars working to these ends have attempted to establish a connection between the state and system-levels of analysis, and have emphasized the role of domestic factors in explaining how state behaviour leads to outcomes at the system level. From the writings of the mainstream neo-classical realists, states are still treated as the determining factors in the analysis of foreign policy and state behaviour, thus these theories are considered to be ‘second image’ theories.
System-centric realism sees the state of anarchy in the international system as its core theoretical building block, and looks here for the roots of state behaviour. There is a long tradition of scholarship that considers the implications of anarchy in the international system. Hobbes’ ‘state of nature’ can be seen as the definitive statement of this branch of realist theory. Even though Hobbes’ philosophical viewpoints maintain assumptions regarding human nature, realist theorists of international relations still borrow heavily from and attempt to extend his systematic description of the state of nature. John Hertz’ explication of the ‘security dilemma,’ for example, is based on Hobbesian logic of anarchy. Waltz similarly raised this notion of anarchy to the core of international relations theory, and created a systemic theory of realism with the international system as its core concern. From these efforts, structural realism emerged.
To illustrate the utility of using units of analysis to classify different theories, we next analyse the disagreement between scholars over the security dilemma. It turns out that realist scholars working within each of the different ‘images’ have different understandings of this concept. First conceptualized by John Hertz, the security dilemma was defined as a social state in which individual powers have no authority above them to enforce behavioural norms or to prevent them from attacking one another. Within this state, mutual suspicion and fear drive individual states to obtain more security by increasing their power. From this definition it can be seen that the roots of the security dilemma are found in the state of anarchy, under which individual states lack the protection of a higher authority. Thus, it is not surprising that when Hertz proposed the security dilemma, he explicitly rejected the human nature element; that is to say regardless of whether human nature is peaceful and cooperative, or domineering and aggressive, is not the question.
Yet, departing from Hertz, Butterfield conceives of this ‘Hobbesian fear’ as man's inherent ‘original sin,’ or as an imperfection rooted in human nature. Butterfield then finds the individual level, or the ‘first image’ to be at the core of the security dilemma.
In recent years, a number of realist scholars have re-considered the security dilemma from the perspective of domestic politics, and proposed revisions to the theory. Of particular importance, the neo-classical realist, Charles Glaser added two non-structural variables when he analysed the implications of the security dilemma: the extent of the adversary's greed and the adversary's unit-level knowledge of the state's motives. Glaser pointed out that if competitors seek not only security, but also have grander desires, competitive policies can cause other countries to give up these other desires and help to avoid conflicts. If adversaries understand the motivation of other powers, it will permit some cooperative policies to be possible, and help to prevent the security dilemma from occurring.
As to which of the three different statements of the security dilemma seems more plausible, this question is beyond the scope of this article. What can be seen from this discussion though is that because the units of analysis and logical starting points are different, realist theorists have different understandings of the origins of the security dilemma, and as a result, there are a wide array of different theoretical extensions and conclusions that are the subject of much debate.
At present, of the three images of realism, the great brunt of this debate takes place between the second and the third images, while realism has largely evolved to render the first image a historical artefact. After the behaviouralist revolution, realist theory became much more scientific, and moved beyond making assumptions about human nature that are impossible to observe or verify, instead absorbing only the more suitable components of human nature realism. In recent years, many debates have flourished around system outcomes and their unit-level determinants. Regardless of whether one looks within or outside of the realist school, more and more theorists have started to emphasize the relationship between the system and its individual units. However, despite this work, there has yet to be a successful attempt at compacting the two into one systematic theory.
Before concluding this section it is important to make a final note regarding the use of unit of analysis as a criterion for classifying realist theories. What we are classifying are not particular theorists, but rather their theories. Any given theorist most likely works on a fairly wide range of problems spanning several different fields, and they will often make different assumptions, or develop theories employing different units of analysis depending on their research questions. Take Waltz as an example—his theory of structural realism obviously belongs to the category of system-centric realism. However, in his book Foreign Policy and Democratic Politics, he compares the differences between American and British foreign policy from the perspective of their domestic political structures with an eye towards crafting a theory of foreign policy. To give another example, Gilpin emphasizes in his work on international political economy that his is a state-centric approach, but yet his theory of hegemonic transitions would be more appropriately classified as system-centric realism. Thus, from the perspective of unit of analysis, it is only possible to complete a rather loose classification of theories, and not a classification of theorists. Further, within each level, the independent variables that scholars select will vary.
Two Directions of Theory Buildings : Theory of International Politics and Theory of Foreign Policy
Scholarly efforts in international relations consist of work in two distinct, but related fields: international politics and foreign policy. Generally speaking, international politics consists of the study of the interactions of three or more states and the outcomes of these interactions. Foreign policy research on the other hand, deals with a particular state and its motivations, policies, directives and behaviour with respect to international affairs. From the perspective of theory building, there are several commonalities in these two areas: first, both the theories are built on the basis of discovery or recognition of patterns; second, theories represent a claim with respect to a casual relationship that explains the empirical patterns. On the other hand, within each respective field, the breadth and scope of phenomena to be explained, as well as the applicability of different theories differ.
Waltz has made a systematic explication of the differences between these two fields. In his view, international politics studies international outcomes that are a result of the behaviour of individual states and interactions between states, which can tell us about the external environment and pressures faced by a state. Foreign policy on the other hand researches the specific behaviours of states to determine how states respond to external pressure. Waltz further distinguishes these two types of theories using the analogy of the differences between theory of markets and theory of the firms in the discipline of microeconomics.
Fareed Zakaria is an example of one scholar who attempts to build theories of foreign policy. He applauds Waltz's point of view, agreeing that theory of foreign policy explains the intent and objectives of states, as well as trends with respect to how states face the external environment, but does not speak of outcomes. This is so because whether a state's efforts are successful depends on the external environment, particularly the objectives and capabilities of other countries.
Summing the above points of view, we argue that theory of international politics explains the frequently occurring phenomena and basic types of behaviour, such as the continuous occurrence of war, the constant emergence of the balance of power or the replacement of hegemons; theory of foreign policy, on the other hand, explains the motivations and behaviours of particular states, for example, the circumstances under which a state forms an alliance or when it chooses to expand. Theory of international politics is considered grand or general theory, while theory of foreign policy is more accurately considered middle range or local theory. The distinction across these two fields actually reflects differences between what each theory is trying to explain, that is, the differences between the dependent variables of interest. This becomes our second criteria for classifying theories of realism.
Many realist scholars, including Morgenthau, Waltz and Gilpin, are engaged in the development of grand or general theories, of which structural realism is perhaps the best example. These theories are considered theories of international politics, and the scope of what they explain includes re-occurring or important phenomena in the international system (of course, this does not preclude these theorists from analysing, evaluating or predicting the state's foreign policy). To demonstrate why these are general theories, it is helpful to consider Waltz's defence of the balance of power theory. Waltz's statement of the balance of power is a widely criticized portion of his theory of structural realism, particularly in the post-Cold War period, when the international power structure obviously had lost its balance, but where all of the major powers did not expand their military resources or attempt to form alliances to hedge against the US power. Critics of Waltz argue that structural realism's balance of power theory has no way of explaining or predicting post-Cold War international politics, or the actions of states in the post-Cold War period. Considering the difference between theory of international politics and theory of foreign policy, it becomes immediately apparent that these arguments do not represent valid critiques of Waltz. As structural realism's balance of power theory is a structural theory, the balance does not depend on the conscious balancing activities of individual states. Waltz's theory instead explains and predicts the balance of power, a commonly observed objective phenomena, using structural analysis of the system, and not a unit-level analysis of the states’ balancing strategies. Because states will always deploy varied strategies to survive, sometimes employing balancing strategies, while other times aligning with a major power, the specific type of strategy that is deployed depends on the circumstances. Thus, these theories never aim to predict individual outcomes at the local level. Instead, the focus is on the overall trend towards a balance of power in the international system.
Some scholars raise objections to this distinction between theory of international politics and theory of foreign policy, arguing that the two are not entirely distinct. These scholars hold that one theory can explain both broad international phenomena and individual state behaviour. Representative of this view is Colin Elman, who counters Waltz by arguing that neo-realism should not pigeon hole itself as theory of international politics. Using a colourful analogy, he argues that the neo-realist ‘horse’ should be let to run on both the course of theory of international politics as well as the course of theory of foreign policy, regardless of whether it wins or loses. Waltz countered by arguing that his old horse absolutely cannot run on the course of theory of foreign policy, and if it tries, it is certain to lose. Elman's argument, however, does not seem so unreasonable, particularly as its original intent was to develop neo-realism's research agenda and expand the space within which it is able to explain and predict.
In order to better understand this debate between Waltz and Elman, it is important to bring to mind the difference between theory building and theory application. It has already been pointed out elsewhere in the article that theory building is concerned with finding and explaining empirical patterns, research focusing on the patterns themselves. Application of theory, on the other hand, consists of using pre-existing theories to analyse particular cases, the focus of the research on a particular aspect or case of the pattern. For example, we can use structural realism to analyse the changing triangular relationship between the United States, Soviet Union and China during the 1960s and 1970s. This theory can tell us about certain trends and deeper causes of the adjustment of Chinese foreign policy and the Sino–US rapprochement during that period, as the changing relations between the three countries fit the general pattern predicted by balance of power theory—that these changes are a result of the shift in the distribution of power taking place at the time. However, structural realism has no way of explicating the detailed movements, policy adjustments or process of re-alignment that occurred during the warming of relations between China and the United States, nor can it determine the specific timeline according to which their relationship would ultimately reach normalization. In order to arrive at a more detailed understanding of a state's foreign policy, we must investigate other factors beyond the distribution of power.
On the basis of this example, we can understand why Waltz maintained his opposition to structural realism as a theory of foreign relations. For Waltz, the international structure was a constraining, not a determining factor of state behaviour. Through competition and adaptation amongst states, structural pressure asserted its effects, causing states with similar levels of power to trend towards the same types of behaviour over the long term. Only under very rare circumstances could the international structure be a determining factor in specific foreign policy or foreign behaviours of states. Generally, international structural pressure and foreign policy output is mediated by domestic factors. In order for the theory to be able to make correct descriptions and accurate predictions of the foreign policy of specific states at specific points in time, many additional variables must be considered (i.e. we must engage in theory building, and not just application). Yet, not only will the introduction of these variables detract from the parsimony of the theory itself, but it will also eliminate the ability of it to generalize as a theory of international politics. It is for these reasons then that we argue that structural realism is a theory of international politics, and a tool that we can use to aid our understanding of foreign policy. However, attempting to apply theory of international politics to foreign policy analysis does not imply that it is also a theory of foreign policy.
That said, there is one disadvantage in Waltz pigeon-holing structural realism as a theory of international politics. Limiting structural realism in this way rejects the possibility of developing a system-level theory of foreign policy. We realize that structural realism as a research programme has two central components or ‘hard cores’. First, it is a system-level theory, second, its primary variable is power distribution. Changing either of these components, for example, adding a unit-level variable, or replacing distribution of power with distribution of identity will cause structural realism to morph into another kind of research programme. However, if we can discover new empirical patterns of state behaviour, foreign policy, interactions between states or the international outcomes affected by these phenomena, and if we can still explain them in terms of the power structure, this will not change the core concern of structural realism. Instead, this is a valid extension of the original theory, and a way of taking structural realism and developing it from a single core theory into a full-blown research programme. This is also to say that insofar as a strong casual relationship can be established between structural causes and foreign policy, neo-realism can develop into a theory of foreign policy.
Within the social sciences, the goal of theoretical research is to look for patterns in behaviour and outcomes, and to explain the casual relationships and casual mechanisms found in such patterns. According to these criteria, we argue that foreign policy research is a field where few theories have been discovered. The debates in this field have been more about the research methods, analytical frameworks and strategies that should be applied to foreign policy research. As a result, in western universities, courses in this field tend to have titles such as ‘Foreign policy analysis.’ Generally, when one speaks of the theory of foreign policy, it is understood as ‘theory’ only in the most general sense.
The difficulty of creating theories in foreign policy research stems from two factors. First, when scholars research foreign policy, they tend to focus on a specific policy process or outcome, which results in the variables becoming context-specific, only suitable for research of one particular case. Second, many different factors at different levels affect the process of policy selection, decision-making and implementation, yet, theory cannot simply be a description of all of these factors. Instead, it must consider the logic relationship between many different variables and opportunely distill them into a system with tight logic. The need to go through this later process highly increases the difficulty of creating theories that can account for foreign policy behaviour. It is important to note though that the different units in international relations can all be theorized to different degrees, as phenomena can always be abstracted into a pattern at some level.
Within the realist school, the primary branch that has emerged over the past several years that is concerned with the construction of theories of foreign policy is what Gideon Rose terms ‘neo-classical realism.’ According to Rose, scholars conducting research within this branch of realism include Randall Schweller, Fareed Zakaria, William C. Wohlforth and Thomas J. Christensen. These scholars do not agree that there is a need for a separation between the internal domestic and external environmental components of state's foreign policy, nor do they intend to construct a general theory with respect to international politics. Instead their core concern is with explaining the foreign policy behaviour of particular states. The policies and behaviours they are concerned with include: grand strategy, military policy, international economic policy, trends in alliances and crisis management. The fundamental tenets of neo-classical realism are that foreign policy is an outcome of international structure, domestic factors and of a complex interaction between the two. Even though state power and the position of states in the international system are determining factors in the selection of foreign policy, at the same time domestic factors can also affect foreign policy. The roles played by system effects and unit-level factors in foreign policy outcomes are considerably different. If system effects are considered as the independent variables, unit-level factors are the intervening variables connecting foreign policy and the international system—they have the effect of strengthening or weakening the influence of structural factors on unit behaviour. Having clarified the effects of system and unit-level variables, these scholars then focus their efforts on the unit factors in the making and implementation of foreign policy.
The theory of neo-classical realism attempts to resolve a major problem in international relations research. We know that neo-realism's successful construction of a macro-theory at the system level has had a tremendous amount of influence on later theoretical research. In similar fashion, for example, Robert Keohane and Alexander Wendt, respectively brought liberalism and constructivism to the system level. At present, the three major schools of international relations are all system-level theories. This state of affairs has caused many scholars to become disaffected, and regardless of whether one looks within the realist, liberalist or constructivist school, there is opposition to the separation between ‘system and unit’ and ‘structure and process’. How to build a bridge between these two and establish a multilevel theory remains a major problem within international relations research. The pathbreaking research in neo-classical realism has much potential with respect to overcoming this difficultly. If at the centre of the theory are casual relationships and casual mechanisms, then it is imperative that the place and effect of different variables in the casual chain are made distinct. This is precisely the task which neo-classical realist scholars have focused on in their work.
That said, theorizing in neo-classical realism is in need of advancement. As of present, the questions and variables are too numerous, and it is still not possible to find a central explanatory variable at the unit level. Right now, it is only possible to conduct a case analysis of the foreign policy history of a single country, which lacks generalizability. Neo-classical realism is not yet a unified theoretical programme, as many scholars put forth a wide range of domestic-level variables such as national intentions, knowledge of policy makers, domestic political structure, offensive/defensive balance, etc. As to which of these variables is most important for foreign policy making, scholars have yet to reach an agreement. If scholars can come to an understanding with respect to a core variable, and create more suitable research designs and empirical research projects, neo-classical realism will be able to be more robust and persuasive as an explanatory theory.
Offence and Defence : A Distinction between Security and Power
The distinction between offensive and defensive realism is one of the most well-known in the discipline. As early as 1991, Synder in his Myths of Empire differentiated between aggressive and defensive realism, which became the dividing line between the two distinct branches of thought that eventually emerged: offensive and defensive realism. From this point until the present, the debate between these two branches of realism has consistently been a central point of contention within the realist school.
At the centre of the distinction between offensive and defensive realism are different assumptions with respect to the way that states tend to behave within the context of anarchy. In more specific terms, it is a distinction with respect to whether states maximize security or power, that is to say, whether power is a means or an end. Some scholars contend that the primary goals that states seek to achieve are survival and security. For these scholars, power is a tool for achieving a goal, and not a goal in itself. Those holding this view are considered defensive realists. Another group of scholars, those that fall within the camp of offensive realism, assume that states seek power as both a means and as an end. This distinction between these types of assumptions is the third of our criteria for classifying branches of realism.
When distinguishing between offensive and defensive realism, scholars should strictly consider the theoretical assumptions of each theory. This point is particularly stressed as some scholarships have incorporated policy aspects into the distinction between the two branches. For example, scholars who have advocated deployment of offensive policies have been labelled by some as offensive realist thinkers, while others argue that the neo-conservative Bush Administration's use of pre-emptive strategy and unilateralism represent offensive realism. These viewpoints incorrectly establish a connection between academic arguments and foreign policy thinking of individual governments. The reality is that most realists, regardless of whether they are offensive or defensive are in opposition to the United States’ aggressive policy position.
It is also important to avoid abstract discussions with respect to offensive and defensive realism, as there are a number of differences of opinion within each of these threads of realist theory. To take offensive realism as an example, all of the scholars within this camp argue that states maximize their power, and further contend that states tend towards aggressive policies. However, with respect to national attribute and behaviour, there are considerable differences found in the literature. Schweller argues that the attributes of states can be either status-quo or revisionist, and that bandwagoning with the superpowers tends to be the common type of behaviour. Mearsheimer, on the other hand, contends that it is very difficult to find a status-quo state in international politics, as the anarchical nature of the international system has left most states with a security deficit. In this view then, the more common type of state behaviour is ‘buck passing.’
Both scholars start from the same assumption that states maximize power, yet arrive at vastly different conclusions. Why might this be the case? This is because Schweller considers several unit-level factors, thereby changing the logic behind the theory. Schweller critiques Waltz for being biased towards the status-quo, and advocates instead that ‘the revisionist state should be brought back in to research’. For Schweller, the critical difference between the two types of states is their level of satisfaction with their position in the international system. However, we know that whether a state is satisfied is a variable: a country might uphold the status-quo at one point in time, while attempting to change it during another. Thus, it is not a fixed characteristic of a state, and as such it is not appropriate to make assumptions with respect to state satisfaction. Furthermore, imputing a state's type as status-quo or revisionist based on observation of a particular behaviour is tautology. As for Mearsheimer, his statement that ‘there are no status-quo states in the international system’ will not be discussed here. It is sufficient to say that this theory is logically consistent, regardless of whether it is appropriate.
Within the defensive realist camp, similar differences are found. For example, Waltz describes the competition for security within the context of anarchy in terms of the Hobbesian state of nature. In his view, there is a lack of security in the international system, and states always have anxiety with respect to their existence. Waltz's theory relies on the assumptions of anarchy and that states seek survival, and his internal logic is consistent. Other scholars do not emphasize the state of anarchy and the security dilemma, arguing instead that security is not in short supply. They see states as having adequate security, primarily as they make several assumptions with respect to domestic factors. Scholars that do emphasize the state of anarchy argue that if states want to maintain their position within the international system, the ideal policy is to maintain the balance of power. Those scholars that do not place much emphasis on the state of anarchy argue that states should maintain a balance between offensive and defensive in their weapons technology, and that they can maintain security through cooperation.
From this discussion it can be seen that whether a state seeks security or power depends on a theoretical assumption, which must be considered together with other assumptions. As this is the case, offensive and defensive realism do not necessarily represent independent branches of the realist school. Instead, it is much more logical to consider them as sub-branches of neo-realism and neo-classical realism.
As several scholars have pointed out, the offence–defence debate is actually found within both neo-realism and neo-classical realism. To make clear the full extent of the differences between offensive and defensive realism, we must also consider the divide between neo-realism and neo-classical realism. Following this logic, Jeffrey W. Taliaferra has demarcated the main theories (or assumptions) within realism (Table 1).
Table 1
Categories of Offensive and Defensive Realism
| Assumptions about Anarchy | |
|---|
| Phenomena to be explained | Defensive realism | Offensive realism |
| (The international system provides incentives for expansion only under certain circumstances) | (International system always provides incentives for expansion) |
| Neo-realism | Balance-of-power theory (Kenneth Waltz); | Hegemonic theory of war (Robert Gilpin); |
| (Theories that seek to explain international outcomes—for example, the likelihood of great power war, the durability of alliances or the likelihood of international cooperation) | Dynamic differentials theory (Dale Copeland); Great power cooperation theories (Robert Jervis, Charles Glaser, Benjamin Miller) | Power transition theory (A.F.K. Organski and Jack Kugler); Balance of interests theory (Randall Schweller); Theory of great power politics (John Mearsheimer) |
| Neo-classical realism | Balance-of-threat theory (Stephen Walt); | |
| (Theories that seek to explain the external behaviour of individual states—for example, military doctrine force posture, alliance preferences, foreign economic policy or the pursuit of accommodative or belligerent diplomacy) | Domestic mobilization theory (Thomas Christensen); Offence–defence theories (Stephen Van Evera, Thomas Christensen, Jack Synder, Charles Glaser and Chaim Kaufmann) | State-centred realism (Freed Zakaria); Theory of war aims (Eric Labs); Hegemonic theory of foreign policy (William Wohlforth) |
Although the arguments and theories of at least one scholar are not properly classified in this table (for example, Taliaferra places Schweller's balance of interests theory into the neo-realist category; however, according to the scholar's own claims, and the general consensus among other scholars, this should be placed under neo-classical realism), the table reflects rather clearly the relationship between the classifications of offensive/defensive realism and level of analysis/scope of explanation, as discussed previously.
As shown earlier, the major differences between offensive and defensive realism are found in their different assumptions. Besides this though, the two theories also disagree with respect to the implications of anarchy, the survival strategy of states and their method of behaviour. In order to make these differences in the branches of realism easier to grasp, we have unpacked the categories in Taliaferra's classification, while maintaining the general scheme (Table 2).
Table 2
A Comparison of the Differences across Different Branches of Realism
| Neo-Realism | Neo-classical Realism |
|---|
| | |
|---|
| Defensive Realism | Offensive Realism | Defensive Realism | Offensive Realism |
|---|
| Phenomena explained | International outcomes and modes of behaviour | International outcomes and modes of behaviour | State policy and behaviour | State policy and behaviour |
| Level of analysis | System | System | State | State |
| Anarchy | Hobbesian | Hobbesian | Benign; relatively peaceful | Unclear; difficult to distinguish |
| Unit-level attributes | No differences across states | No differences across states | Differences such as geography, technology and knowledge are important | Distinction between status-quo and revisionist states (there is a contradiction here with the assumption regarding power maximization) |
| Power | Means, not an end; seek sufficient power | Means and an end, maximize power | Means and not an end; maintain offensive/defensive balance | Means and an end; maximization of power |
| Conclusion about state behaviour | Enlightened national interests; maintain the balance of power | Seek hegemonic power | Great powers cooperate; ‘buck passing’ | Expansion |
Although the debate between offensive and defensive realism has attracted much attention recently, the dividing lines between the two are not consistent, as can be seen from the arguments made by many realists. As Waltz pointed out, realism is not offensive or defensive—all states use numerous means to preserve their existence. The use of an offensive or a defensive strategy is always determined by the specific context. Many scholars argue that Waltz's theory should be classified as defensive realism, yet he does not deny that states will expand their power when circumstances permit. He has also made it clear in the past that he believes that states’ objectives range from just seeking to exist on one end of a continuum to domination on the other. Mearsheimer also admits that states are not always under all circumstances seeking to maximize power. Although some states may trend towards the absolute pursuit of power, the pressures of the system will often prevent them from achieving maximization of power. This can be seen from his design of the grand strategy of the United States. In order to prevent other states from hedging against the US power, Mearsheimer advocates that the United States should engage in a strategic consolidation of its power, playing the role of an ‘offshore balancer’. Many realists, regardless of whether they are in the offensive or the defensive camp agree that this should be the role of the United States.
Prudent power and enlightened interest are the basic values of political realists. Morgenthau saw prudence as the supreme virtue of politics and thought that if states want to advance and protect their own interests, they must respect the interests of other states. Waltz also pointed out lucidly that power is merely a means that can be employed, and that sensible politicians pursue a moderate amount of power. The history of international relations offers many examples of states that pursued the expansion of power to the extremes, and in doing so, sowed the seeds for their own destruction. If it is conceded that the international structure is a restriction on the behaviour of states, then states cannot seek to expand power without limit. At a minimum, their motivations and behaviour, intentions and outcomes cannot be divorced from one another. Offensive realists such as Mearshemier who see states as seeking absolute power to great extremes, although they show the pessimism and drama of power politics, do not fall within realism's fundamental tradition of prudence and enlightenment.
Balance and Preponderance : The Two States of the International System
Realists have different understandings of the nature of the international system. More specifically there are two different types of descriptions, explanations and predictions with respect to the implications of a concentration or a diffusion of power. The first view holds that the international system generally maintains a balance of power, while the other holds that the normal state of the international system is a preponderance of power. Recently, scholars have termed these two points of view as balance-of-power realism and hegemonic realism. Jack Levy argues that many people link realism to the concept of a balance of power, but that, in fact, such a connection represents a conceptual misunderstanding. That almost all balance-of-power theorists are realists does not mean that all realists are balance-of-power theorists. Christopher Layne has pointed out that the debate over the ideas of balance of power and hegemony is a major fault line in the realist school.
In a series of papers, Levy introduced the distinction between balance of power and hegemony. According to Levy, balance-of-power realism holds that in order to guarantee their own survival, states within the international system (especially great powers) try to prevent hegemonic powers from emerging. When a great power acquires a predominant position in the international system, other powers will typically ally to balance against it. Although the system will on occasion be out of balance, it will tend towards a balance of power over the long-term. Great powers generally will balance, using both internal and external strategies, and in general will not ally with the hegemon. Classical realism, Waltz's neo-realism, offensive/defensive realism and neo-classical realism can all be considered types of balance-of-power realism, despite the fact that these various branches do not agree with respect to which states will seek to balance and under what conditions they will balance.
Hegemonic realism disagrees with this argument, holding that hegemonic powers tend to emerge in the international system. These powers will establish a set of political, economic and behavioural norms to manage the international system, a concentration of power thereby bringing stability to the system. This stability will waver and major wars will occur at the points when a new hegemon rises to challenge the hegemonic power and there is a period of hegemonic transition. This branch of theory includes power transition theorists such as Organski, as well as Gilpin's hegemonic stability theory and William Thompson's long cycle leadership theory.
In order to compare the differences between balance-of-power realism and hegemonic realism, we can use Levy's treatment of the two to identify three main differences. First, the two have different understandings of the basic nature of the international system and its operation. According to the balance-of-power theory, a balance is the natural state of the international system. Waltz goes as far as to claim that any theory of international politics, by definition has to be a balance-of-power theory. By this, he means that theory of international politics can only study regular patterns, and as balance of power is the only regularity within international politics, it is the only object of study. Hegemonic theorists on the other hand argue that the more common state of the international system is for a preponderant state to emerge and play the role of a leader in the international system.
Second, the two branches have different understandings of stability, war and peace in the international system. Balance-of-power theory contends that when the power of major states is relatively equal, the system maintains stability. Hegemonic theory on the other hand argues that there will be relatively little war between great powers when one hegemonic power controls the international system, and that under these circumstances stability is maintained with relative ease. Of course, there is again disagreement within each of these theories with respect to the number of poles in the system and its ability to remain stable, as well as regarding the system's ability to prevent war. For example, Morgenthau argues that a multipolar system is more stable, while Waltz maintains the view that a bipolar system is more stable.
Lastly, the two branches differ with respect to foreign policy and strategic decision making. Balance-of-power theory holds that states within the international system (especially great powers) will opt to maintain a rather weak position, and not establish linkages with the predominate power, that is to say, they will employ a balancing strategy; hegemonic theory on the other hand maintains that because hegemonic powers can maintain stability in the system, and provide public goods, that it is in the interest of other states to ‘chain-gang’ or align with the hegemon.
Even though the balance of power and hegemony represent two important categories within the realist school, we do not necessarily agree that this is the most suitable distinction to make. First, the goal of creating a typology of theories is to distinguish between independent branches of thought, and not to differentiate points of view. A point of view in itself cannot become a branch of theory. Only if a particular class of viewpoints shares a common theoretical core and the same basic assumptions can it be considered a branch of theory. Using this criterion to consider Levy's typology, we can see that within both balance-of-power theory and hegemonic theory there are many obvious differences. For example, he classifies classical realism, Waltz's neo-realism, offensive/defensive realism and neo-classical realism as balance-of-power realism, yet each of these theories has its own independent theoretical core and set of basic assumptions, and each can be considered its own branch of theory. With respect to the balance of power, the focal points of these theories are also not necessarily the same. Some of these study how the balance of power is formed through the distribution of power within the international system (Waltz's structural realism), while others study the balancing behaviour that states adopt (neo-classical realism), while yet others study both of these factors (classical realism). Similar complexity exists within the so-called class of hegemonic realisms, including power transition theory, hegemonic stability theory, and long cycle leadership theory, each of which also suggests different means of hedging against a hegemonic power. Levy clearly recognizes this as he notes ‘conceptions of power in terms of land-based military power in nearly all applications of balance of power theory should be contrasted with hegemonic stability theory's focus on financial and commercial strength, with power transition theory's measurement of power in terms of gross national product, and leadership long cycle theory's conception of power in terms of naval capability (at least until the 20th century) and dominance in leading economic sectors’.
Second, not only do the theories that are classified as balance-of-power realism or hegemonic realism not share similar core concerns and assumptions, but also the substance of what they study is also entirely different. Some focus on what is traditionally considered international politics, focusing on political and military affairs; while others are more concerned with international political economy, focusing on issues at the nexus of economics and politics. Hegemonic stability theory and long cycle leadership theory are two examples of theories that focus on the latter. As these theories are used to study different issues the two lack comparability.
Third, the evolution of the international system itself is a dynamic process within which balance-of-power and hegemony are two intermittent phases of its evolution. Maintaining consistent criteria to evaluate the two, it is impossible for the international system to be in both of these states at any given time. Whether the basic state of the international system is a balance or a preponderance of power can be distinguished. Any theory that studies the state of the international system should be able to explain both of these states, and the appearance of either state—for example, structural realism is able to explain the current unipolar system.
From the three points made above, it should be apparent that balance-of-power realism and hegemonic realism are both conceptually too broad, and that attempts to classify them within a typology of theories can only make realism even more difficult to understand. Thus, it does not seem that this distinction with respect to the nature of the international system is all that useful as a criterion for classifying realist theories.
Conclusion
Realism has a long intellectual tradition within the study of international relations, and it has already developed into a mature school of thought with several distinct branches of theory. In one respect, these different schools have enriched the realist school. Yet, they have also inevitably created difficulties with respect to classifying the different types of realist theory, leading to many different classification schemes and labels.
This article has analysed the problem of classifying contemporary realist thought with respect to four dimensions: unit of analysis, phenomena to be explained, assumptions with respect to the motivations of states and the state of the international system. We argue that the first three of these criteria can be accepted as valid criteria for classifying realist theories. The fourth of these, however, is too broad to distinguish between theories, and is not a suitable criterion against which to classify different branches of realist thought. With the first criteria, unit of analysis, this article has distinguished three types of realism: human nature realism, state-centric realism and system-centric realism. Using the criterion of phenomena to be explained, two further categories emerge: theory of international politics and theory of foreign policy, which are presently represented by neo-realism and neo-classical realism. The final criterion, assumptions regarding the motivation of states renders one last distinction between offensive and defensive realism. In opposition with the generally accepted view though, we argue that this offensive and defensive realism should be discussed within the framework of neo-realism and neo-classical realism.
In order to better understand the different criteria and the relationship and differences between the different branches of thought, we present a chart (Figure 1) rendering our typology. The chart is divided into quadrants based on differences in the dependent and independent variables. As Figure 1 indicates, the starting point for realism (independent variable) has two dimensions, system and unit, while the phenomena to be explained (dependent variable) consists of either international politics or foreign policy. Along these two dimensions, the various branches of realism are placed. After the independent and dependent variables for a particular branch of theory are determined, it can be placed in one of the quadrants on the graph, thus rendering clearly the different distinctions within the realist school.
Figure. 1
Typologies of realism.
As can be seen from Figure 1, classifying realist theories according to the three criteria discussed above places them in several different positions on the chart. The empty space in the first and the fourth quadrants does not imply that there have been no attempts in the realist school to construct a state-level theory of international politics or a system-level theory of foreign policy. Rather, these are left blank as efforts in these two areas have yet to develop into mature branches of realism. It is likely that these two spaces represent the direction that realism will develop in the future. From this chart it can also be seen that it is not the case that the branches of realism distinguished by these criteria are unrelated. Instead they either intersect with or are subsumed within one another. Thus, before comparing or evaluating the relationship between different branches, it is important that the criteria are carefully noted.
One additional note is needed here. The aforementioned classification cannot necessarily incorporate all aspects of modern realism. The writings and contributions of some realist scholars cannot be confined within a single branch of realist theory, further, the various classification schemes might intersect or overlap. Naturally, in comparison with the recent careless use of labels, and new terminology, a precise set of classificatory criteria is very useful for explicating the core concerns and major distinctions made in the debate within the realist school, and is of further use with respect to providing a proper understanding of the different branches of realism. The accumulation of knowledge should pay careful attention to maintaining its continuity. It is not the case that every new distinction made or every intellectual innovation should become a new conceptual or theoretical system. Every time a realist scholar adds a new theoretical assumption it is not necessary to use a new label or term of reference for his idea, nor should the scholars’ attempts to classify or evaluate different ideas result in a proliferation of new terms, otherwise it could result in unnecessary obfuscation of concepts and misunderstanding. This article presents a preliminary analysis of the issues related to the classification of realism with an eye towards increasing awareness and debate of these issues, and on the basis of this, paves the path for the future development of the realist school.
(Reproduced from the Science of International Politics, with kind permission of the authors and the Institute of International Studies, Tsinghua University)
