“War made the state, and the state made war”, this cyclical representation of war and peace presented by Charles Tilly is a defining feature of international relations (IR). By using theory in this discipline, the recurring theme of war and peace amongst states can again be expanded upon. Realism and liberalism are two core theoretical concepts in IR which attempt to provide a conceptual framework in which themes like this can be examined. Realism focuses on power politics and the inherent selfishness of human nature over moral and ethical values. Liberalism instead rejects power politics and focuses on the concept of harmony and balance amongst competing states. These theories thus provide opposing opinions on the causes of war in a context of an interconnected anarchical world. They again provide differing perspectives on the obtainment of peace in this context. In this essay, the main points of difference between a realist and a liberal approach to the causes of war and peace will be discussed. This will be achieved by looking at the key voices of realist and liberal thought, as well as particular theories that help provide a foundation for peace.
Power politics in realism is the idea that a person or state uses their power or influence over others. Jack Donnelly notes that the theory of power politics is based on two fundamental suppositions: the egotistical characteristics of human nature and the state-system operating in a context of international anarchy. The structural implications of international anarchy are explored by Thucydides and Thomas Hobbes, both of whom are considered to be main voices on realist thought. Thucydides in his ‘History of the Peloponnesian War’ notes on the issue on anarchy on an international scope and its connection to the processes of war. He identifies the key characteristic for a state to go to war with another state – fear: “What made war inevitable was the growth of Athenian power and the fear which this caused in Sparta”. Hobbes in ‘Leviathan’ instead proposes that the weight of egoism in human nature and anarchy is equal. This equality suggests that humans are naturally driven by competition, diffidence and glory. Hobbes notes that the natural condition of man is one in a state of war. Kenneth Waltz argues that these structural effects of an anarchic system are what shapes the tension between states: “Because some states may at any time use force, all states must be prepared to do so-or live at the mercy of their militarily more vigorous neighbors”. This indicates that there is a constant conflict and struggle of security between states that may not necessarily lead to war, but it is a possibility. E. H. Carr suggests instead that “it is profitless to imagine a hypothetical world in which men no longer organize themselves in groups for purposes of conflict”. This highlights how egoism and conflict is a core intrinsic value of human nature which greatly influences and defines power politics.
Contrastingly, liberalism stresses the ideals of individualism, equality, and moral virtue. Individuals have a responsibility to respect others, value them as ‘ethical subjects’ and conduct social action. This constitutes to the processes and actions within war, as liberalism acknowledges that war is a possibility, and if it were to happen, then it should follow the criteria of the just war theory. The just war theory is a doctrine that guides military ethics. It identifies a set of morally justifiable criteria to ensure war does not happen for untenable reasons. The criteria are based off of two Latin terms: jus ad bellum (‘right to go to war’) and jus in bello (‘right conduct in war’). This thus dictates the ethics and moral actions surrounding going to war and being at war. Jus ad bellum has seven points of criteria: just cause, comparative justice, competent authority, right intention, probability of success, last resort, and proportionality. Jus in bello instead has five: distinction, proportionality, military necessity, fair treatment of prisoners of war, and no means malum in se. These essentially outline that civilians should not be targeted in times of war and malevolent methods of warfare are not tolerated and not ethically right. Liberals attest that just war is waged in terms of self-defense, or in defense of another. This contrasts the realist perspectives of Hobbes and Machiavelli, who believe that war in general is waged in pure malignant fashion which does not constitute it to be a ‘just’ war.
The balance of power theory in neorealism focuses on the attainment of peace amongst states. This theory, which realists use to explain the possible causes of peace, highlights how states can gain power both internally and externally. Waltz notes on how internal efforts include increasing economic and military strength, whereas external factors include forming alliances with other states. This thus allows for nations to be in a state of equilibrium with one another and to also maintain that balance of power to benefit all actors. Waltz argues that states must accept this shared interest, “only if stakes recognize the rules of the game and play for the same limited stakes can the balance of power fulfil its functions for international stability and national independence”. Thucydides, however, notes that the issue with the concept of anarchy is that there is no principal authority. Therefore, the only way to preserve order is through a balance of power. As previously stated, Thucydides believes that fear is a fundamental aspect for going to war with another state. He notes that as this is an inherent human characteristic then war is inevitable. Due to the growth of Athenian power, Sparta became defensive, which essentially undermines the achievement of peace. Therefore, without measures in place to balance power and polarity peace is disrupted and war arises. Hobbes’ theory on state of nature notes that without a centralized government, anarchy remain and so does the constant prospects of war. Whereas Thucydides believes that in a balance of power the stronger states still prevail over the weaker ones, Hobbes suggest that every person is equal: “The weakest has strength enough to kill the strongest, either by secret machination or by confederacy with others that are in the same danger with himself”.
While realism believes peace can be achieved through the balancing of powers, liberalism instead suggests that the democratic peace theory can effectively cause peace. The democratic peace theory states that democracies are hesitant to engage in war with other democratic countries. This theory, however, holds innate flaws, as the academic definitions of ‘democracy’ and ’war’ can be greatly manipulated. John Owens notes this as realists will claim that “when power politics requires war with a democracy, liberals will redefine that state as a despotism; when power politics requires peace with a non-democracy, they will redefine that state as a democracy”. Democratic peace theory was inspired by Immanuel Kant’s idea on perpetual peace and how the people would not vote to go to war: “Under a non-republican constitution, where subjects are not citizens, the easiest thing in the world to do is to declare war. Here the ruler is not a fellow citizen, but the nation's owner, and war does not affect his table, his hunt, his places of pleasure, his court festivals, and so on. Thus, he can decide to go to war for the most meaningless of reasons, as if it were a kind of pleasure party...”. Thus, if all states were republics, or in this case democracies, then peace could be obtained. Owen again notes that liberal ideology on peace prohibits war on other democracies and instead causes war with illiberal actors. This causes the birth of democratic institutions that further push the prospects of peace.
In conclusion, there are main points of theoretical differences between realism and liberalism and their approaches in examining the causes of war and peace. By analyzing the realist works of classical historians like Thucydides, who provide political and military theory that remains universal despite differing contexts, or Thomas Hobbes, a key Enlightenment figure, who provides the fundamental understanding on anarchy and hierarchy in the political sphere, a framework emerges in evaluating the prospects of war and peace. Contrastingly, by applying liberal notions, like the democratic peace theory, which arose form Kant’s perpetual peace philosophy, or the just war theory, a further understanding arises on a liberal perception on the causes of war and peace. From this, a comparison can be made between these two integral antithetical notions of IR. It can also show the dissimilarities between both concepts as many realists perceive liberal peace theories of democracy, as a fantasy that cannot be explained by a persuasive ‘mechanism’. This again is emphasized by the liberal notion of the rejection of power politics, which is a core aspect of realist IR thought. While these differences are striking, it thus provides a deeper understanding of central aspects of discourse and discipline which allow for to meaning to arise.