Michael Doyle, in this article, indicates that liberal states which base on individual rights are basically opposed to war. Nevertheless, liberal states are different. They are actually peaceful, but they also tend to make war. To show these differences, Michael Doyle explains three different theoretical traditions of liberalism in his article. These traditions are liberal pacifism, liberal imperialism, and liberal internationalism. (p.73)

Liberal Pacifism: Joseph Schumpeter, in his article “Sociology of Imperialism” that published in 1919, concerned pacifying effects of liberal institutions and principles. Schumpeter focused on the interplay of capitalism and democracy as the base of liberal pacifism. So, he looked at the sociology of historical imperialisms which rest on the effect of a war machine, warlike instincts, and export monopolism, that all based on the atavism. Although, in the past, war machine was necessary because of wars; now, there are wars because of the war machine. The warlike instincts stem from the war machine, but also some states, like Persians, are warriors from the beginning. Export monopolism incites imperialist expansion to extend nation’s closed markets. Export monopolism depends on the tariffs that imposed by monarchs in the past. These all three sources of imperialism are an atavism of the absolute monarchies. In modern era, to Schumpeter, because imperialists satisfy their individual interests, their imperialistic wars are objectless. (p.73,74)

Schumpeter states that capitalism and democracy are necessary to establish peace, because when capitalism and democracy developed, imperialism will disappear. For him, capitalism creates unwarlike tendency and creates democratized, individualized, and rationalized populace. According to Schumpeter’s liberal pacifism, only war profiteers and military aristocrats gain from war. When there is a free trade foreign raw material and food stuffs are accessible to each nation, as a result, no class gains from forcible expansion. Also, if a nation that is backward culturally makes economic relations dependent on colonization, which of the civilized nations assumes the task of colonization is not important. (p.74)

The inconsistency between warlike history of liberal states and Schumpeter’s pacifism emphasizes three extreme assumptions. First, his ‘materialistic monism’ minimizes non-economic objectives such as glory, prestige, ideological justification, or pure power of ruling. Second, the political lives of individuals are homogenized. Third, like internal politics, world politics are homogenized. Materially monistic and democratically capitalist all nations engage with free trade and liberty together. Machiavelli’s liberal imperialism does not share these assumptions. (p.75)

Liberal Imperialism: Machiavelli denies that republics are pacifistic. Instead, they are the best form of state for imperialism. Machiavelli’s republic is not a democracy, but bases on individual rights. There are consuls that serve as kings, senate as an aristocracy that administer the state, and people in assembly. (p.75)

According to him, liberty stems from the disunion meant competition of senate, consuls and people; then, there will be compromise. Also, popular veto creates liberty, because, when the powerful few want to dominance, others veto and protect state’s liberties. Nevertheless, people need to be managed because they are lack of ability to expand their state. So, consuls and senate plan the expansion. Machiavelli advises that to expand your state, you should organize it as a free and popular republic like Rome rather than as an aristocratic republic like Sparta. Thus, Machiavelli is an advocator of the liberal imperialism. (p.75,76)

Liberal Internationalism: Modern liberalism left two legacies. First one is the pacification of foreign relations among liberal states. Liberal pacifists state that liberal states exercise peaceful limitation, and separate peace which refers to a deal to stop military hostilities among states exists. Separate peace also suggests the promise of maintenance of peace and refers possibility of global peace. But, this does not demonstrate that the peace among liberals is statistically remarkable and that liberalism is the only way to peace. Second one is international imprudence. Peaceful limitation seems possible only in liberals’ relations with other liberals. Liberal states make many wars with non-liberal states. Many of these wars have been defensive and thus prudent. (p.76,77)

Kant’s theory of liberal internationalism makes these legacies more comprehensible. Kant argues that perpetual peace will be guaranteed by ‘three definitive article’. First one emphasizes that constitution of the state must be republican to preserve freedoms. Second Definitive Article suggests that liberal republics will progressively establish peace among themselves by means of the pacific union that will maintain the rights of each state. Third one establishes a cosmopolitan law that will be limited to conditions of universal hospitality.(p.78)

To Kant, perpetual peace is a condition for ethical action that requires harmony among men even their discord. Peace is an ethical duty, because all men see each other as ends rather than instrument for ends, only under conditions of peace. However, guarantee of perpetual peace does not base on only ethical behavior. Kant shows that fear and force also motivated men for perpetual peace. Kant explains that liberal states maintain peace among themselves; and these states make wars with non-liberals and thus suffer due to sad experience of wars. (p.79)

Finally, cosmopolitan law attaches material incentives to moral behaviors. The cosmopolitan right makes ‘spirit of commerce’ possible. As a result, states tend to promote peace and avoid from war. Liberal economic theory advocates that these cosmopolitan ties stem from a cooperation of international division of labor and free trade. (p.80,81)

In conclusion, the promise of perpetual peace, sad experience of war, and the experience of a partial peace prove the necessity of world peace. They are foundations for moral citizens and statesmen who striving for peace. (p.81,82)