Comparing and Contrasting Classical Realism and Neorealism

Comparing and Contrasting Classical Realism and Neorealism: A Re-examination of Hans Morgenthau’s and Kenneth Waltz’s Theories of International Relations


Realists often trace their intellectual roots to Thucydides’ classic account of the Peloponnesian War in the fifth-century B.C.  It would however take nearly 2,500 years before the study of international politics became an institutionalized academic discipline and for the first classical realists in the newly established field to emerge. Amongst them the German-Jewish émigré to the United States, Hans Morgenthau, came to have the largest impact on the field. In his magnum opus from 1948, Politics Among Nations, Morgenthau formulated an account of political realism that dominated the studies of international politics for over two generations. Eventually, the intellectual hegemony of Morgenthau’s classical realism was succeeded by the founding father of neorealism, Kenneth Waltz. Waltz’s attempt to develop a systemic and scientific realism in his 1979 book Theory of International Politics divided this school of thought into two blocks: classical realism and neorealism. The purpose of this essay is to compare and contrast these two realist traditions by engaging with the works of Hans Morgenthau and Kenneth Waltz. The aim is to challenge the conventional wisdom within the field of IR and present a more sophisticated and nuanced understanding of these two theorists.

This approach is premiered for several reasons. The limited scope of this essay makes a vast survey of different classical realist and neorealist positions impractical and would only amount to a highly descriptive essay. The alternative approach, to treat realism and neorealism as monolithic blocks is also dismissed since there are significant differences amongst scholars within the same realist block as well. As such, it would thus be arbitrary to lump them together under two predefined labels. Hans Morgenthau and Kenneth Waltz are chosen as representatives of classical realism and neorealism on basis of their reputation as the most influential thinkers in their respective branch of realism, a point that was proven in a recent survey amongst IR faculty (Maliniak et. al., 2007: 17, 19).

This essay proceeds in five sections. The first section outlines the mainstream conception of classical realism and neorealism. The second section compares and contrasts Morgenthau’s and Waltz’s definition of power. The third section examines these two theorist’s position on the levels of analysis. The fourth section explores the normative and critical elements of Morgenthau’s and Waltz’s thinking. The fifth and last section of this essay summarizes the preceding arguments and argues that labeling ideas rather than individuals is more fruitful when assessing scholarly work.

The Orthodox View of Classical Realism and Neorealism

Before an analysis of Morgenthau’s and Waltz’s work can take place, it is necessary to highlight how classical realism and neorealism is usually depicted in the mainstream literature.

According to the orthodox view, Realism is concerned with the world as it actually is rather than how it is ought to be. In other words, it is an empirical rather than a normative paradigm (Morgenthau, 1956: 4). Realism is also pessimistic and emphasises the recurrent patterns of power politics as manifested by reoccurring conflicts, rivalries and wars (Jackson and Sorensen, 2007: 60). In this gloomy world, concepts such as the balance of power and the security dilemma become the main realist analytical tools (Buzan, 1997: 53). Realists of all strands also consider the state as the principal actor in international affairs. Special attention is afforded to great powers as they have the most leverage on the international stage (Mearsheimer, 2001: 17-18). Furthermore, it is the national interest that animates state behaviour as they are essentially rational egoists, guided by the dictates of raison d’état (Brown, 2005: 30). Finally, Realist’s maintain that the distribution of power or capabilities largely determines international outcomes (Frankel, 1996: xiv-xv).

There are however four key differences between classical realism and neorealism. First, classical realist locate the roots of international conflict and war in an imperfect human nature while neo-realists maintain that its deep causes are found in the anarchic international system. Second, the state is ontologically superior to the system in classical realism, in contrast to neorealism, allowing more space for agency in the former approach (Hobson, 2000: 17). Third, classical realists differentiate between status-quo powers and revisionist powers while neorealism regards states as unitary actors (Schweller, 1996: 155). Fourth, neo-realists attempt to construct a more rigorous and scientific approach to the study of international politics, heavily influenced by the behaviourist revolution of the 1960’s while classical realism confine its analyses to subjective valuations of international relations (Georg and Sorensen, 2007: 75).

The rest of this essay will focus on the merits of this orthodox understanding of realism and contest some of the myths this process has generated about realist thinkers. The first theme that will be analysed in this spirit is Morgenthau’s and Waltz’s understandings of power.

Defining Power

Morgenthau and Waltz both see the international arena as a competitive and hostile stage where power is the main currency. That is why the concept of power is at the heart of their analysis of international politics.

John Mearsheimer (1995: 91) summarizes the orthodox view on how power is defined within the realist paradigm in the following statement: “Realists believe that state behaviour is largely shaped by the material structure of the international system”. This quotation however deeply misrepresents Morgenthau’s definition of power. This is evident when Morgenthau states that: “Power may comprise anything that establishes and maintains the power of man over man …. from physical violence to the most subtle psychological ties by which one mind controls another” (Morgenthau, 1965: 9). For Morgenthau, the most important material aspect of power is armed forces, but even more significant is a nation’s character, morale and quality of governance (Morgenthau, 1956: 186). The validity of this reading of Morgenthau is further enhanced when he contends: “power …. tends to be equated with material strength, especially of a military nature, I have stressed more than before its immaterial aspects” (Morgenthau 1965: 9). Michael Williams (2005:109) is thus right when he claims that the closest affinities to Morgenthau’s extremely broad understanding of power are to be found in the works of Michael Foucault and Pierre Bourdieu and not in the narrow and materialistic conception of power realism often is accused of.

Waltz offers a considerably thinner definition of power or capabilities than Morgenthau. His estimation of power includes the following components: “size of population and territory, resource endowment, economic capability, military strength, political stability and competence” (Waltz, 1979: 131). Even though Waltz evidently privileges material factors, non-material dimensions of power are also present in his theory as manifested by his emphasis on political stability and competence. The reason for Waltz’s predominant emphasis on materialism is due to his commitment to ’scientific’ realism. Consequently, Waltz limits his definition of power to mainly tangible variables as they are much easier to quantify.

There are thus vast differences between Morgenthau and Waltz in their definition of power. The formers’ understanding of power poses a fundamental anomaly to the orthodox view since ’soft’ power trumps ‘hard’ power in Morgenthau’s account. In this respect, Waltz’s position is far easier to reconcile with the traditional view. Indeed, Waltz’s rather narrow conception of power is predominantly, but not entirely, materialistic.

Why do States Struggle for Power?

There is a wide consensus within the literature that classical realists and neo-realists answer this fundamental question in opposing ways. Classical realism supposedly emphasizes human nature while neorealism locates causation in the anarchic international system (Brown, 2005: 92). This section seeks to examine the merits of this categorization by comparing and contrasting the writings of Morgenthau and Waltz.

Morgenthau’s explanation is mainly, but no solely, confined to the first image which he bases upon a fixed and universalistic account of human nature. The first principle of political realism makes this point clear: “politics, like society in general, is governed by objective laws that have their roots in human nature” (Morgenthau, 1956: 4). According to Morgenthau, the struggle for power at the international level is largely the result of animus dominandi, the ‘political mans’ urge to dominate others, a concept influenced by Nietzsche’s metaphysics on the ‘will to power’ (Peterson, 1999: 100-101). However, Morgenthau goes beyond human nature and moves up to the second level of analysis. He regards the state as a collective reflection of political man’s lust for power and the unit which carries out its impulses at the international stage. The state is thus the referent object of Morgenthau’s theory and the agent pursuing power in international affairs, highlighting Morgenthau’s dependence on the unit-level. The third image is also present in Morgenthau’s account of the struggle for power. Anarchy is not the deep cause of power competition but a vital permissive force. The absence of world governance means that there are no constraints on man’s basic desires, reflected in state behaviour, to dominate others (Shimko, 1992: 290-293). In a hierarchic order however, the pursuit of power would be abolished as the animus dominandi would be constrained by a global leviathan (Morgenthau, 1956: 477). Hence, human natures innate desire to dominate others which is the driving force of state behavior can only take place as long as the international system remains anarchic. Through this narrative, Morgenthau also eloquently links all three levels of analysis together.

Kenneth Waltz, nevertheless, regards Morgenthau as a first image theorist and criticizes his approach on three accounts. First, Morgenthau’s account of human nature is entirely hypothetical since we cannot empirically verify what the true human nature is. This in turn makes it impossible to assess the validity of his thesis (Waltz, 1959: 166). Second, Morgenthau’s essentialist conception of human nature is problematic since a constant cannot explain variation. To paraphrase Waltz: if human nature was the cause of war in 1914, it was by the same token the cause of peace in 1910 (Waltz, 1959: 28). Third, Waltz accuses Morgenthau of reductionism since the latter tries to explain the whole by the sum of its parts. Reductionism fails to account why the patterns of international politics constantly reoccur even though the actors and their character are in a constant change (Waltz, 1979: 65, 74).

To overcome what Waltz regards as deficiencies in Morgenthau’s work he attempts to locate causation at the systemic level instead. Indeed, Waltz contends that the anarchical international system inevitably leads to the logic of self-help and power politics. According to Waltz (1979: 87) states who struggle for power are simply following the dictates of the international system in order to survive in an international order where there is no global leviathan to offer them protection. By providing this explanation, Waltz tries to restrict himself to the systemic level and avoid ‘reductionism’. Waltz however fails with this attempt as his theory is dependent on the unit-level in order to function. As Richard Ashley and Alexander Wendt have pointed out, Waltzian structuralism presupposes state preferences. International anarchy cannot possibly impel states to struggle for power if they do not share any ambitions (Guzzini, 1998: 129). Waltz is seemingly well aware of this point and makes interference at the second level of analysis by assuming that states pursue strategies for survival, in order to operationalize his theory (Waltz, 1979: 91). This motivational desire alone cannot however generate power competition. Randall Schweller convincingly argues that in an anarchic system where all states primary goal is survival, the units would have no incentive to pursue power at all since that would risk undermining their principal goal: survival. In Schweller’s words: Waltz constructs “a world of all cops and no robbers” and must therefore make further interventions at the unit-level and bring revisionist goals into his analysis in order to trigger power competition (Schweller, 1996: 91-92). Reductionism thus seems to be unavoidable, even for Waltz.

As this section has shown, Morgenthau assigns the deep causes of power struggles to the first image while Waltz attributes it to the third image. However, both scholars make use of other levels of analysis as well. Without incorporating both systemic and unit-level explanations neither Morgenthau nor Waltz would be able to explain why states pursue power. The difference between the two lies in the fact that  Morgenthau’s ‘bottom-up approach’ takes human nature as the starting point and moves up the levels of analysis, while Waltz ‘top-down approach’ begins at the third image and slowly move down to the unit-level, without ever reaching the individual level. Contrary to the conventional wisdom then Morgenthau’s classical realism cannot be seen as a strict first image theory and Waltzian neorealism is not a purely systemic theory.

The Critical and Normative Dimension of Power Politics

There are different opinions on the role normative and critical analysis plays in classical and neorealism. Some claim that both strands of realism overlook this dimension of politics (Burchill, 2001: 99), others argue that this aspect of theorizing in only apparent in classical realism (Lebow, 2007: 53) while a third strand maintains that realists of all kinds are driven by a normative and critical agenda (Sorensen and Jackson, 2007: 77). This section aims to bring some clarity to this important issue.

Critical and normative analysis shines through in the work of Morgenthau. Following Hannah Arendt, Morgenthau makes a distinction between the vita contemplativa and the vita activa, the first concept corresponds to truth and the second to power. In Morgenthau’s world the two realms are at odds with one another as they are oriented towards different goals. While truth tries to unmask power for what it actually is, in order to open up space for normative and critical challenges to the status-quo, power tries to cloak itself and pretend to be the bearer of truth and justice in hope of maintaining the existing order. Morgenthau argues that the task of the scholar is to speak truth to power and expose it for what it actually (Morgenthau, 1970: 14-15). This is the task Morgenthau undertakes when he relentlessly attack rational liberalism for uncritically accepting relations of domination by cloaking it under the banner of ‘rationality’ and ‘harmony of interest’ (Williams, 2005: 96). Rational liberalism then only reinforces the status-quo which Morgenthau claims to be contrary to the purpose of political science as a discipline designed to unsettle power and bring about change (Cozette, 2008: 8).

Morgenthau’s approach in Truth and Power is also fully consistent with his key principle: “interest defined as power”. This is because Morgenthau has an extremely broad understanding of power as has already been demonstrated but also an almost boundless definition of the national interest. This is evident in the following passage of Politics Among Nations: “The goals that might be pursued by nations in their foreign policy can run the whole gamut of objectives any nations has ever pursued or might possible pursue” (Morgenthau, 1965: 8-9). Echoing Weber, Morgenthau thus argues that prudent and ethical behaviour can be a part of the state objective. Indeed, good foreign policy “complies both with the moral precept of prudence and the political requirement of success” (Morgenthau, 1965: 7). Yet, Morgenthau clearly recognizes that states may choose not to act in such manner since moral principles do not serve as effective political restraints (Williams, 2005: 187).

Even though Waltz has spoken truth to American power since at least the 1970’s, his theoretical work is dry of critical and normative engagement (Halliday et. al., 1998: 373). Waltz’s lack of interest in normative and critical analysis does not however stem from a belief that theories should solely explain as one would expect (Waltz 1979: 6). Other explanations must therefore account for Waltz’s antipathy towards critical and normative theorizing, here are two plausible renditions. First, Waltz’s theory maintains that structure determines the behaviour of the units within it. Consequently, only structural changes are able to affect international outcomes in world politics (Waltz, 1979: 108). Hence, there is very little room for agency in Waltz’s world and it would be superfluous to engage in prescriptions when it is systemic factors that ultimately decide state behavior. Waltz is open to the prospect of change in the structure of the international system but regard it as a formidable challenge, unlikely to happen any time soon (Waltz, 1986: 329). Second, Waltz wrote his book during the height of the Cold War which was characterized by bipolarity between the two great powers of the time, the United States and the Soviet Union. Since Waltz (1964: 881-909) contends that the bipolar distribution of power is the most stable and peaceful form of international order he was contempt with the status-quo and had therefore no reason to challenge it. These two explanations might account for Waltz disinterest in critical and normative analysis.

This final theme has demonstrated a sharp division between Morgenthau’s and Walt’s writing’s. While the former openly engage with critical and normative analysis the latter do not address these concerns at all. If we only consider the writing’s of Morgenthau and Waltz, Richard Ned Lebow’s proclamation seems to be correct: only classical realism is preoccupied with the normative and critical dimension of politics.


This essay has compared and contrasted the classical realism of Hans Morgenthau with Kenneth Waltz’s neorealism. It has also examined and challenged the conventional wisdom on what realism as a school of thought is supposed to encompass and questioned some of the similarities and differences that supposedly exists between classical and neorealism. This essay should therefore be seen as a contribution to the increasingly sophisticated engagement with realism in IR (Williams, 2007: 5).

The first section of this work presented the orthodox view which maintained that realism is: state-centric, materialist, pessimistic and empirical. The conventional literature also maintains that classical realist’s locates causation in the human nature, make distinctions between status-quo powers and revisionist states, emphasize the importance of statecraft and believe in a subjective social science and differs from neorealism in these aspects. The second section examined Waltz’s and Morgenthau’s definition of power, while the former conceived it in largely material terms the latter regarded immaterial factors as more important. Morgenthau’s understanding of power is thus an anomaly to the orthodox view. The third section compared the levels of analysis in Morgenthau’s and Waltz’s work. The former mainly rooted the pursuit for power in human nature while the latter emphasized international anarchy. However, as was demonstrated both scholars utilize structural and unit-level explanations in their theories. The binary opposition between classical realism and neorealism in terms of level of analysis as presented in the mainstream literature is therefore false. The fourth and final section contrasted the normative and critical aspects of Morgenthau’s and Waltz’s writings. Even though both scholars are mainly concerned with constructing an explanatory theory the former did incorporate critical and normative elements into his theory.  Morgenthau’s concept of ’speaking truth to power’ clearly demonstrated this point. Waltz was however reluctant to undertake normative and critical analysis. Two explanations were given for this. First, his theory leaves little room for agency making policy prescriptions superfluous. Second, he was contempt with the ’stable and peaceful’ bipolar world during the Cold War and had therefore no reason to challenge it. Commentators claiming that critical and normative considerations is absent from realism may thus be right with regards to Waltz but not Morgenthau.

This essay has shown the problems of trying to fit Waltz’s and especially Morgenthau’s ideas into predefined labels such as ‘realism’ or ‘classical realism’ and ‘neorealism’. The argument is not that there is no shared core within realism but rather that the categorization of its advocates into various labels ultimately tells us very little about their theories and might in some cases even completely misconstrue their positions as this essay has demonstrated. Indeed, restricting people to a label considerably reduces the complexity, breadth and richness of scholars thinking and leaves us with an arbitrary, sterile and simplistic understanding of their work.  This approach is however unfortunately widespread in IR and academics who fundamentally disagree on the essence of international politics are arbitrary lumped together into a school of thought they might not even themselves ascribe to. At better way of assessing the contributions to the field of IR has recently been suggested by Ken Booth (2008: 510-526). He advocates a move from labeling people to labeling ideas.  A move towards labeling ideas would not only do justice to the major contributions made to our field but may also lead to a more sober and holistic understanding of international politics in extension.


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Written by: Arash Heydarian Pashakhanlou
Written at: Aberystwyth University
Written for: Simona Rentea
Date written: 2009 (revised September 2010)

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