Idealism is an approach in International Relations (IR) derived from liberal thought and refers to the nineteenth century and the post World War One era. The most important key elements of idealism in IR, firstly is the view that man is inherently good, peaceful and rational where ‘human reason and processes of social learning renders progress possible.’  Secondly, Doyle argues that ‘the interdependence of commerce,’ is central to idealist IR.  Thirdly, the creation of democratic states and global political institutions based on ‘principles of legitimacy,’ is a key characteristic of idealist IR theory.  Finally the ‘moral rights which all persons equally have simply because they are human,’ is also a key attribute of idealist IR.  Peace, according to idealists is the pinnacle of human progress and therefore the underlying aim of all these elements of idealist theory is how to politically, economically and socially achieve and maintain peace.
It can be argued that the key features of idealism are realistic and relevant in the current international political system. Although idealism has its limitations, which will be discussed, these limitations don’t diminish the pragmatic nature of idealist IR theory. In order to establish the extent to which these key elements are practical and applicable, the four core attributes of idealist IR theory mentioned will be analysed according to the following criteria: does the theory explain the current international system, is there evidence and examples of how idealist key elements apply to the international political system and is idealist IR theory able to impact global politics and instigate change?
Idealist IR theory is based upon the normative view that peace is not a natural state of being however, that human nature is inherently good, peaceful and rational and therefore progressive. Idealists believe that mankind needs to establish institutions that allow for humanity to progress towards peace. Plato discussed the nature of man in Republic asking ‘there is a kind of good which we welcome not because we desire its consequences but for its own sake?’ sustaining the idea that man needs to initiate ways to achieve peace.  The central aim of idealism is to achieve cooperation globally through a mutually beneficial international system that provides economic, social and political stability. This aspiration is a foundational aspect of economic interdependence, global political cooperation and the protection of human rights.
An illustration of how the belief that humanity is inherently good, peaceful and rational was through the creation of the League of Nations after World War One in 1919. The aim of the League of Nations was to promote European peace and avoid another European war. Founded on Idealist principles the creation of the League of Nations shows how idealist IR theory can be put into practice and successful. For example the League of Nations in 1921 resolved the land dispute between Finland and Sweden over the Aalands and also solved the disagreement over the nationality of Upper Silesia.
Although the beginning of World War Two marked the end of the League of Nations formally, the United Nations (UN) was created after World War Two to replace it. Kant explores the idea of a ‘pacific union,’  like the League of Nations or UN, which Doyle comments ‘leav[ing] a coherent legacy on foreign affairs.’  This is a viable example of how the idealist rational, to prevent European war, lead to several nations deciding to set up an institution that could practically achieve this. It emphasises how the core idealist characteristic that human nature is good, peaceful and rational applies to contemporary global politics. Thanks to idealist IR theory the establishment of the League of Nations explains the origins of the UN, who aim to make the international political system progressively more peaceful, contributing to the global political order.
It should be noted that although the idealist opinion that man is good, peaceful and rational is realistic in both theory and practice, this view conjures questions about how you define the good moral nature of man. Sandel points out that one of the major critiques of idealism is that ‘its moral basis is increasingly unclear.’  The question as to whether universal principles can be established based on man’s moral consciousness is not answered by idealism. Additionally another constraint of idealism is the normative value of peace and whether or not this is a truly achievable aim. These critiques highlight the limitations of idealist IR theory, however they do not take away from the fact that the despite the ambiguous nature of the concept of good, there is an overarching idea of international morality, which the international community aim to achieve. It can therefore be said that the idealist standpoint that human nature is good despite the conceptual constraints is an achievable characteristic of idealism.
The belief that mankind is inherently good, peaceful and rational underlies all idealist theory in IR and can be applied to the economy. In idealist IR theory one of the key elements is economic interdependence. Debatably the increase in globalisation economically means that there has been an increase in free trade and therefore international economic cooperation. It can be argued that free trade encourages cooperation is because the ‘complex layers of economic interdependency ensure that states cannot act aggressively without risking economic penalties imposed by other members of the international community.’  The result is an increase in global peace through the prevention of war. This is arguably because the cost of military action to a state is too high. It can be stated that idealism has meant that international competition is replacing warfare to ensure economic stability and prevent an economic crisis. Part of idealist economic IR theory is interdependence theory, which states that economically integrated states have an invested interest in each other’s peace and prosperity and are therefore less likely to go to war. Jorgensen supports this view stating that ‘free trade is preferable to mercantilism, because trade produces wealth without war.’  Idealists emphasise that the self-regulation of free market economy means state actors and non-state actors like multinational companies (MNC’s) in an interdependent global economy need to work together to national economy. Again the cost of war to both parties is too high and as a result economic interdependence increases international peace. Doyle supports this view and observes that ‘citizens appreciate that the benefits of can be enjoyed only under conditions of peace.’ 
A realistic example of how economic idealist IR theory applies to the current global system is the creation of European Union (EU). Globalisation has meant that European markets have been becoming increasingly integrated since the nineteenth century. The creation of the EU has meant that free trade has been a political policy adopted by all twenty seven member states and consequently all member states have become interdependent. Doyle highlights the benefit of this stating that ‘a liberal zone of peace, a pacific union, has been maintained and has expanded despite numerous particular conflicts of economic and strategic interest.’  The EU was set up not only to promote economic growth but also to endorse peace. The intension alongside the aims of the UN was to prevent another major war like World War One or Two. The EU is a practical example of how idealist theory means that economic integration promotes international peace and cooperation.
It is equally essential to consider that, although the economic aspect of idealist IR theory is pragmatic, there are drawbacks. The main concern with economic global interdependence is that it is not always beneficial to every nation involved. Often the relationship between developed nations and developing nations with free trade are unequal and unfair. For example the EU promotes free trade but this is primarily in Western Europe. Particularly for developing nations competing in a global market means that they are subject to unfair competition, where the EU states have a trade zone that indefinitely secures the free trade of their products. Critics of idealism point out that free trade is often accompanied by exploitation such as MNC’s taking advantage of cheap labour in the developing world. Despite the occasional imbalanced nature of free trade, free market capitalism is the dominant economic global order. The central point that economic interdependence encourages peace remains the same. Fukuyama supports this idea and stresses that ‘the virtues and ambitions called forth by war are unlikely to find expression in liberal democracies.’ 
Economic interdependence in idealism is closely associated with democratic institutions and states. A fundamental element of idealism is political cooperation between states and international institutions which ’emphasises individual rights, constitutionalism, democracy and limitations on the power of the state.’  Idealists believe that, through political cooperation and the spread of democracy, peace can be achieved and maintained. The freedom exercised within democracies cultivates a political culture where ‘we are taught to respect the magistrates and the laws… We are free to live exactly as we please and yet we are always ready to face danger.’  The two theories associated with liberal political peace are, the democratic peace theory and perpetual peace. Democratic peace theory maintains that democracies don’t go to war against each other and are ‘inherently peaceful simply and solely because in these states citizens rule the polity and bear the costs of wars.’  Perpetual peace is the growth of a peace zone which ‘nullifies all existing causes of war, even if they are unknown to the contracting parties.’  These theories show how the idealist approach in IR can have the potential to achieve a greater degree of peace relations internationally. It can be affirmed that more nations have ascribe to a democratic constitution than any other political structure like Poland, a former USSR state.
The spread of democracy in line with idealist international relation theory can be viewed as feasible because it described a past and current trend evident in the post-colonial period particularly in Africa. For example there is a very high proportion of newly independent African states that have become liberal democracies, such as Ghana, South Africa and Tanzania. This trend is also evident in for Latin America and the former USSR states. The most significant observation is that as the number of democracies has increased; the number of global wars has decreased. Linklater supports this view commenting that ‘liberal states wind up all on the same side, despite the real complexity of the historical economic and political factors that affect their foreign policies.’  The idealist principle that peace should be the political norm is continually emphasised because democracy promotes a society that sees war as irrational. It can therefore be said that because democratic states are politically united and able to resolve conflict without military warfare, democracy in idealist IR theory promotes peace. This example demonstrates that idealism is realistic because the spread of democracy has shaped current global political development.
On the other hand it is important to note that there are exceptions to the democratic peace theory. Two democratic states have gone to war against each other. For example the Kosovo War in 1999 when NATO alliances fought the Yugoslavian and Albanian armed forces. This example proves that the democratic peace theory is not completely accurate. However when studying IR or any social science, it is almost impossible to prove that any theory is completely accurate. It is also worth mentioning that concepts such as democracy and freedom are essentially contested; ‘what is freedom to those who make no use for it?’  Each concept carries varying relevance internationally making them difficult to measure and define. This is further complicated when examining how to distinguish between a democratic and a non-democratic state. How should democratic states react to non-democratic states? These limitations of political idealism demonstrate how, despite the relevance of idealist IR theory, it lacks a consistent analysis of non-democratic states. This however does not detract from the fact that political idealism explains the democratic nature of our current global system and it can be said that idealist IR theory is workable and evident through the spread of democracy.
In conjunction with democracy and democratic political institutions a core aspect of idealist IR theory is the ‘protect[ion] of human rights, and the support of international cooperation, to profess international law and support international norms.’  Idealism believes that there is a universal morality which focuses on universal principles that apply to every state with their domestic and international society. Idealist IR theory states that the fixed rights of the man should be enforced through the rule of law. Montesquieu, an Enlightened thinker who wrote L’Esprit de Lois, believed in the universal rule of law as the ‘science of society.’  Idealist universal principles such as human rights are rooted in international law. This is essential to idealist IR theory becoming an increasingly important aspect of state policy as ‘the primary justification of government is that they serve to secure these rights.’ 
Consequently idealist IR theory has lead to an increase in the practice and application of international law. This illustrates how realistic and significant idealism is as part of the global political system. Idealist IR theory is arguably viable because it has shaped international relations by helping to establish the international organisations that aim to protect human rights. For instance the Universal Declaration of Human Rights in 1948 by the UN is built upon idealist IR theory foundations which ‘all countries, have accepted.’  Furthermore international tribunals such as the International Criminal Court (ICC) established in 2002 aim to prosecute human rights abusers according to international law. In the case of Democratic Republic of Congo the ICC has put General Katanga on trial for genocide. Both the Universal Declaration of Human Rights and the ICC illustrate how idealist IR theory has been able to impact global politics, resulting in a practical way of enforcing the key charcterisitc defending of human rights. Idealism has allowed global politics to ‘connect the rights directly with morality.’ 
The relevance of idealist IR theory is clear; however there is a normative assumption that idealism can eradicate human rights abuses. The question is, whether idealists expect and assume too much of humanity. A further concern with idealist IR theory is how you define concepts such as human rights and freedom when despite the idea of universal principles cross-culturally these concepts are very different. From international perspective, human rights is often a western concept that means ‘even when rights have universally distributed they have often not been had equally.’  This means that although the protection of human rights is practiced, it is ethno-centric and therefore difficult to achieve. In response to this the UN states that ‘Human rights are not only a common inheritance of universal values that transcend cultures and traditions, but are quintessentially local values and nationally-owned commitments grounded in international treaties and national constitutions and laws.’ Despite the practical restrictions of idealist IR theory, the international community believes in defending human rights globally which again emphasises that idealist IR theory is realistic, as it explains and has shaped the political global order.
In conclusion idealism can be said to be a functional approach to studying international relations because it explains several trends that are occurring in the current international order. The League of Nations showed how the idealist view of human nature as rational and good became the foundation of the UN and the international community. The idealist belief of man as rational underpins the idea that, through economic interdependence and free trade peace can be achieved. It also explains why free trade capitalism is the dominant economic global policy not only in Europe but also in Africa and Asia. Associated with free trade capitalism as the global economic order, democracy and democratic institutions are a realistic key element of idealism that has become the prevailing political constitution internationally. Democratic state policy has emphasised the individual and aimed to protect human rights, which is also a central element of idealism. Finally, it can therefore be stated that with the acknowledgment of the constraints of idealism, idealist IR theory is the most realistic approach to studying international relations.