Functionalism emerged in the early twentieth century as a distinctive approach within International Relations, rooted in the belief that international cooperation could be advanced through the creation of technical, non-political institutions addressing concrete human needs. The approach was most famously articulated by David Mitrany, who argued that states could transcend conflict by cooperating in specific functional areas such as health, transport, communication, and economic management. Mitrany proposed that “form follows function,” meaning that the institutional structure of international cooperation should evolve organically around the functions required to solve global problems. The central assumption behind this argument was that shared human needs create natural incentives for collaboration, and that such collaboration—being based on technical expertise rather than political bargaining—would generate a spillover of trust, habits of cooperation, and ultimately a form of peace grounded in interdependence. Functionalism emerged against the backdrop of the two World Wars, when hopes for avoiding renewed conflict rested partly on designing new, rational, pragmatic institutions capable of taming the destructive potentials of nationalism and geopolitical rivalries. The belief that technical experts rather than diplomats could more effectively address certain transnational problems forms the normative core of the functionalist imagination.

The first major assumption of Functionalism concerns the separation of political and technical domains. Mitrany insisted that functional problems such as postal delivery, river basin management, or health surveillance could be administered by specialised agencies without being drawn into wider ideological or territorial disputes. This assumption reflected the progressive rationalism of the era, which believed that modern science and bureaucratic expertise could surpass the limitations of traditional diplomacy. Scholars such as Inis Claude noted that Functionalism attempted to construct a “world without politics” at least in limited spheres, imagining a global governance architecture run by impartial professionals insulated from national political pressures. The optimism behind this assumption rested on the view that technical cooperation is inherently apolitical, yielding universal benefits and therefore being less susceptible to contentious bargaining. The functionalists argued that if states delegated authority to specialised agencies in areas of common interest, this would gradually erode the rigidity of sovereignty and demonstrate the advantages of cooperation over conflict. Thus, the assumption was not merely descriptive but deeply normative, embedded in the hope that institutional design could reshape the behaviour of states.

A second assumption central to Functionalism is the idea of incrementalism or the cumulative process of spillover. Mitrany argued that successful cooperation in one technical sector would naturally lead to cooperation in adjacent sectors, as states recognise the benefits of shared frameworks. While Mitrany himself did not use the term “spillover” in the same way that neofunctionalists later did, his argument clearly anticipated the logic that functional interdependence creates a self-reinforcing chain of cooperation. This assumption stems from a rational-institutionalist view of actors, assuming that once states begin to experience positive-sum outcomes from cooperation, their cost-benefit calculations shift toward deeper integration. Critics such as Stanley Hoffmann, however, argued that this assumption overly underestimated the resilience of national identities and political conflicts. Nonetheless, Functionalism’s incremental logic formed the basis of later institutional theories that emphasise path dependence and increasing returns to cooperation, a theme widely recognised in theories of international regimes.

A third important assumption is that sovereignty is flexible and divisible, capable of being partially delegated to functional agencies without risking national autonomy. This assumption challenged the Westphalian conception of indivisible sovereignty, positing instead that authority could be systematically dispersed across a network of specialised institutions. Mitrany argued that the authority of international agencies would grow not through coercion but through performance—“authority by function”—suggesting that states would willingly cede control when they saw tangible benefits. This idea foreshadowed later debates on pooled sovereignty in regional organisations like the European Union and resonates with contemporary discussions on the authority of global governance bodies such as the WHO or WTO. However, the functionalist assumption that states voluntarily share authority purely based on efficiency has been criticised for downplaying the political nature of sovereignty, which is often linked to identity, legitimacy, and domestic politics rather than rational efficiency alone.

A fourth assumption embedded in Functionalism is the belief that peace is best achieved through cooperation rather than through power balancing. Mitrany was deeply sceptical of traditional diplomacy and the balance-of-power system, arguing that such mechanisms are inherently conflict-producing. Instead, he believed in what may be labelled a technocratic peace, where cooperation around shared needs creates mutual dependence that reduces incentives for war. This assumption directly challenged the core realist belief—articulated by Hans Morgenthau—that international politics is fundamentally characterised by conflictual interests rooted in human nature and anarchy. Functionalists instead adopted a more optimistic view of human motivations, aligning more closely with liberal and institutionalist assumptions. They held that by shifting issue-areas away from high politics toward low politics, international institutions could bypass the zero-sum dynamics that often accompany security issues. However, critics argue that the assumption that peace can be engineered incrementally through technical cooperation ignores the fact that many conflicts are rooted in structural inequalities, historical grievances, and geopolitical rivalries that cannot be resolved through technical problem-solving alone.

When subjecting these assumptions to critical examination, one must consider the realist critique which argues that Functionalism fails to adequately account for the centrality of state power in shaping international outcomes. Realists such as E.H. Carr condemned the liberal optimism of Functionalism, noting that the separation of political and technical realms is artificial, because even seemingly benign areas such as trade, finance, or technology often have strategic implications. For example, control over communication networks or energy infrastructure is deeply intertwined with security interests. The functionalist hope that technical agencies could remain apolitical thus appears naïve, given that powerful states often use international institutions to pursue their strategic interests, as demonstrated in debates around IMF conditionalities or the governance of the internet. The assumption that experts can operate independently of political influence has also been critiqued by critical theorists who argue that the notion of technocracy masks underlying power asymmetries and depoliticises profoundly political issues. Thus, Functionalism’s attempt to separate technical and political spheres is vulnerable to extensive theoretical challenges.

Another critique concerns the incrementalist spillover assumption, which has been empirically tested most notably in the context of European integration. Neofunctionalists such as Ernst Haas expanded the spillover concept, but even Haas later acknowledged that spillover is contingent on political will and cannot be assumed to occur automatically. The stagnation and reversals within the EU project, especially visible during the Eurozone crisis and Brexit, demonstrate that cooperation in one sector does not guarantee cooperation in others. Functionalism failed to incorporate the role of domestic politics, ideology, or identity, which can interrupt or reverse integration. The lack of sensitivity to political constraints means that Functionalism’s incrementalism often overestimates the linearity and inevitability of cooperative pathways. This weakness reveals an underlying assumption that states are rational problem-solvers, which is not always supported by empirical evidence.

The assumption of divisible sovereignty also becomes problematic when confronted with contemporary assertion of nationalism and the resurgence of geopolitical rivalries. Many states remain reluctant to delegate authority even in highly technical domains when such delegation threatens their strategic autonomy. For instance, disagreements over data governance, vaccine distribution, and climate technology transfer show that states guard certain forms of authority even when cooperation could yield mutual benefits. Functionalism underestimated the emotional, identity-based, and symbolic dimensions of sovereignty, which are often invoked by domestic political actors for legitimacy. Constructivist scholars such as Alexander Wendt argue that sovereignty is socially constructed and deeply tied to state identity; therefore, treating it merely as a divisible administrative category misses its political and ideational importance. Hence, the functionalist belief in the gradual erosion of sovereignty appears overly idealistic.

Despite these critiques, the contemporary relevance of Functionalism remains significant in certain respects. Globalisation has dramatically expanded the number and influence of international organisations, especially in technical areas such as aviation safety (ICAO), health (WHO), telecommunications (ITU), marine regulation (IMO), and nuclear energy oversight (IAEA). These bodies reflect functionalist logic by focusing on specific issue-areas and employing experts rather than diplomats. The COVID-19 pandemic demonstrated the importance of functional cooperation: no state could manage the crisis alone, and institutions such as the WHO, although criticised, played indispensable roles in information sharing, coordination, and standard-setting. This aligns with the functionalist assumption that interdependence necessitates cooperation around shared human needs. Climate change, cyber security, global supply chains, and financial stability further illustrate how states rely on technical bodies to manage complex transnational challenges. Thus, Functionalism retains its relevance in explaining why specialised agencies continue to proliferate and why cooperation in certain areas persists even when political relations are strained.

However, the relevance of Functionalism today is more partial and conditional rather than universal. Contemporary global governance reflects a hybrid of functional cooperation and deep political contestation. While communication protocols, health reporting standards, or shipping rules may be governed by technical institutions, these areas often become politicised during crises, revealing the limits of functional separation. The politicisation of the WHO during the COVID-19 crisis, the contestation over 5G technologies, and the strategic calculations embedded in climate finance negotiations show that technical cooperation is vulnerable to broader power struggles. Furthermore, functional cooperation has not necessarily led to spillover into political integration; states often compartmentalise cooperation, maintaining strict boundaries between technical and political domains. Thus, while Functionalism remains useful in understanding the proliferation and operation of international agencies, it is far less persuasive in suggesting that technical cooperation naturally leads to peace or deeper integration.

In addition, new forms of global governance challenge some functionalist assumptions while reinforcing others. For example, the involvement of non-state actors such as multinational corporations, NGOs, epistemic communities, and transnational advocacy networks resembles Mitrany’s belief that cooperation should be driven by function rather than by state diplomacy. Yet the power dynamics within these networks, including the disproportionate influence of wealthy states or corporations, complicate the functionalist assumption of egalitarian cooperation. The emergence of regime complexes, polycentric governance architectures, and multi-stakeholder platforms demonstrates that governance today is fluid and decentralised, echoing Mitrany’s idea of overlapping functional authorities but also highlighting the messy and contested nature of global governance that Functionalism did not fully anticipate.

In conclusion, Functionalism in international relations rests on four defining assumptions: that technical and political domains can be separated; that cooperation in functional areas produces spillover; that sovereignty is divisible and delegable; and that peace can be advanced through technocratic cooperation rather than political negotiation. These assumptions were historically shaped by the optimism of the post-war era and the belief in scientific rationality as a tool for global order. While critics from realist, critical, and constructivist perspectives argue that Functionalism underestimates power, identity, and political conflict, the approach retains a measure of relevance in the contemporary world, particularly in explaining the growth and resilience of specialised international agencies that operate on technical mandates. Nevertheless, the idea that functional cooperation naturally evolves into political integration or global peace is far less convincing today. Functionalism remains a valuable but limited lens: it illuminates how and why states cooperate in low-politics areas, but it cannot fully explain the political, strategic, and ideational forces that shape global governance. Its relevance today is therefore significant but circumscribed, offering insights into the mechanics of cooperation while leaving the broader dynamics of conflict and power largely to other theoretical frameworks.

The functionalist approach in International Relations emerged as a pragmatic response to the recurrent failures of power politics in ensuring global stability. Developed most prominently by David Mitrany, functionalism argues that the path to peace and order lies not through traditional diplomacy or balance of power but through technical cooperation on non-political issues. In this sense, functionalism reframes IR by shifting attention from high politics to low politics, emphasising that cooperation built around shared needs is more durable than fragile political agreements.

Mitrany believed that war is caused by the inability of states to fulfil basic social and economic needs, which in turn fuels insecurity and conflict. Therefore, international organisations should focus on functional tasks—transport, health, finance, communication, environment—where states have mutual interests. When states collaborate to solve these specific, technical problems, they create habits of cooperation and interdependence that make conflicts irrational. This logic directly contributes to an environment where peace becomes a by-product of functional integration, rather than the outcome of coercive political arrangements. The success of bodies like the Universal Postal Union, WHO, and ICAO demonstrate how states can cooperate apolitically even during high political tensions.

Functionalism contributes to global peace by depoliticising cooperation, thereby reducing the space for geopolitical contestation. By arguing that cooperation should be organised by experts and not political elites, functionalists suggest that technical knowledge is less prone to manipulation and thus more conducive to solving common problems. This reduces mistrust among states and fosters a sense of shared purpose. Moreover, as Robert Keohane later noted in his analysis of complex interdependence, such functional cooperation creates institutional linkages that make states increasingly reliant on each other, diminishing the incentive for unilateral aggression. This reinforces a stable international order in which economic and social networks act as constraints against military conflict.

Functionalism also shapes peace by promoting gradual integration. Mitrany’s idea of a “ramification process” argues that cooperation in one technical sector spills over into others, creating a web of interdependence that eventually encompasses large areas of governance. This contributes to systemic stability, as states become embedded in cooperative frameworks. The development of the European Coal and Steel Community (ECSC), although later theorised by neo-functionalists like Ernst Haas, reflects this functionalist insight. By integrating coal and steel—key war industries—Europe reduced the possibility of conflict through shared management of vital resources.

However, functionalism’s contribution to peace is not absolute. Critics such as Stanley Hoffmann argue that functional cooperation alone cannot overcome nationalistic impulses or security concerns. High politics continues to intrude into functional areas, as seen in debates over global health governance during pandemics or arguments over climate finance. Moreover, functionalism underestimates the role of power asymmetries; powerful states can dominate technical agencies, subtly reshaping outcomes to suit their interests.

Despite these limitations, functionalism remains significant in global politics because it institutionalises predictability, transparency and mutual dependence. Its emphasis on pragmatic cooperation, issue-based governance, and expert-led problem solving supports a more stable international environment where incentives for conflict decline. In an era defined by transnational challenges like climate change, pandemics and cyber threats, the functionalist belief that peace emerges from cooperation on shared problems continues to shape global governance and contributes meaningfully to international peace and order.