Death of international organizations. The organizational ecology of intergovernmental organizations, 1815–2015

The dataset compiled for this article shows that, of 561 IGOs created since 1815, 218 (39%) have since ceased to exist. How surprising is this mortality rate from the point of view of existing theory? Answering this question is not as straightforward as one might think. As already discussed, a theoretical assertion of robustness does not entail a prediction of organizational immortality. IGOs may be reasonably good at weathering environmental change or resisting obsolescence and still occasionally succumb to environmental shocks or internal crisis. Furthermore, whilst existing theories predict IGO longevity, this raises the question, ‘long-lived compared to what?’¹⁰ Take the example of the European Commission for Control of the Danube. Established in 1856 by the Treaty of Paris to regulate navigation and technical work on the lower Danube, the Commission exercised broad powers approaching those of a sovereign state, maintaining its own ships, police and courts (Krehbiel 1918). Widely perceived by its members as indispensable to ensuring the free flow of international commerce in Europe, the Danube Commission weathered the Austro-Prussian War of 1866, and adapted smoothly to the defeat of Germany in World War I, only to be dissolved in 1939 as the rapid expansion of Russian power in Eastern Europe undermined Western control of the important waterway. We might think it unremarkable—both intuitively and from the perspective of extant theory—that an IGO created in the mid-nineteenth century should have now ceased to exist. After all, it was created under distinct historical circumstances. Indeed, we might reasonably contend that the fact that the Danube Commission endured for more than 70 years before geopolitical events rendered it anachronistic is consistent with a theoretical expectation of organizational robustness. However, dismissing the termination of longstanding IGO as theoretically unchallenging in this way would be too quick. Consider that of twenty-four IGOs founded before 1900, eleven were still operative in 2015. This suggests that organizational death due to 'old age' or ‘historical anachronism’ cannot be regarded as an expected or banal event. To put it differently, given that half of IGOs founded during the nineteenth century are still alive today, the death of the other half cannot be simply regarded as a ‘natural’ outcome in need of no further explanation.

A second puzzle for extant theory arises from the fact that—unlike the Danube Commission—the historical lifespan of most IGOs has been relatively short.¹¹ The average ‘age-at-death’ for IGOs terminating between 1815 and 2015 is a mere 23 years. While this figure masks significant variation in the lifespan of individual organizations it indicates that many IGOs fail to reach old age, calling into question assumptions of robustness and longevity. Indeed, the historical record shows that many defunct IGOs terminated surprisingly soon after being created. Of 218 IGO deaths, 47 (22%) occurred within one decade of organizational founding, and 51% of deaths struck within two decades. Thus, while some IGOs are long-lived, many die young. The inability of extant theories to account for such variation in survivability constitutes an important blind spot.

This section turns to empirical analysis. I start by operationalizing IGO termination. Next, I conduct a cross-section analysis of the population of dead IGOs with the aim of establishing when and how these organizations disappeared. The following section uses a Cox Proportional Hazard analysis to identify specific factors that are associated with higher or lower IGO survivability. Part 3 summarizes and discusses my findings in light of existing IO theories, and points to avenues for further research and theory development.

Before analyzing patterns of IGO mortality it is necessary to clearly define the phenomenon we are seeking to understand. When can an international organization be said to have died? And what are the processes that may lead to its termination?

The COW IGO datasets use two simple criteria to define the death of an IGO. First, an IGO is coded as ‘dead’ if it has gone ten consecutive years without a plenary meeting or other evident activity. Second, an IGO is considered dead if it has been replaced by, or merged with, another organization (Pevehouse et al. 2004). These broad criteria, however, fail to distinguish the multiple paths through which an IGO may terminate. Knowing how an IGO terminates may hold important clues to understanding why it has terminated. In this section, I therefore draw on literature in international institutional law to specify five distinct mechanisms through which IGOs can die (Expiry, Dissolution, Succession, Merger, and Desuetude). These mechanisms are used to code individual cases in my dataset.

My analysis is based on a novel dataset that contains information on 561 IGOs founded between 1815 and 2005, recording their fate as of 2015. The main data were taken from the COW IGO dataset.¹⁷ This data was supplemented with data from the Yearbook of International Organizations, various handbooks and encyclopedias, UN treaty collections and information from individual IGO websites. The resulting dataset includes all but twelve organizations listed in the COW IGO datasets,¹⁸ plus an additional forty-three organizations not listed in COW (either due to omission, or because information on their founding may have become available since that dataset was last updated), bringing the total to 561.

As already discussed, whilst they provide an invaluable resource for studying IGOs, the COW IGO datasets contain limited information on how deceased international organizations have died. They further fail to distinguish organizations according to mandate or geographic region, essentially treating all IGOs as functionally and geographically equivalent. To provide a more fine-grained picture, I therefore code five different design features of IGOs.¹⁹ Additionally, for defunct IGOs, I have coded information on both when and how they terminated.

The second feature, Membership, refers to the rules for who can join an IGO. Following Shanks et al. (1996), I distinguish between ‘Inclusive’ organizations whose membership is in principle open to all states, and ‘Restrictive’ organizations that limit their membership according to either geographic or functional criteria.

Organizational scope refers to the range of issues covered by an IGO. At one end of the spectrum are broad IGOs such as the UN, which focus on a range of highly diverse economic, security and political goals. At the other end are narrowly specialized IGOs that focus on few limited, technical issues (Koremenos et al. 2001:770). In between lie organizations with medium scope that link several related issues (say, finance and trade) but whose roles and activities are nonetheless confined to a single issue-area (e.g., economic cooperation).

Region codes the geographic region in which an IGO’s members are based (as opposed to where its primary activities are conducted). Following Shanks et al. (1996), I define IGOs whose membership spans more than a single region, but that nonetheless have geographically restricted membership as ‘Intercontinental’. The Commonwealth organizations mostly fall into this category, being neither regional nor truly global. IGOs with global span, such as the UN, are coded as ‘global’.

One could identify additional features of institutional design that might hypothetically influence IGO robustness. For example, Boehmer et al. (2004) code IGOs according to their degree of institutionalization.²⁰ They find that highly institutionalized IGOs with a measure of bureaucratic autonomy are more likely to promote peace among member states than minimally institutionalized organizations (on the benefits of bureaucratic autonomy, see also Gray 2018). One might hypothesize (for similar reasons) that highly institutionalized IGOs are less likely to terminate than organizations with low institutionalization.. Other potentially relevant features are organizational budgets and voting-rules. Are IGOs with larger budgets on average more robust? Or do limited budgets allow some IGOs to survive ‘under the radar’? Does qualified majority voting extend the life-span of an IGO by helping to avoid deadlock? However, comparing attributes such as degree of institutionalization or voting procedures for IGOs founded centuries apart would be fraught with ambiguity and imprecision owing to the historically specific nature of such aspects, and to the fact that both institutionalization and IO autonomy may vary over time (see Gray 2018). Similarly, measuring and comparing the budgets of IGOs operating during the nineteenth century with contemporary peers would be relatively meaningless. I therefore concentrate my initial, population-wide analysis on basic features such as Mandate, Number, Region, and Membership which can be accurately measured and compared across a large, heterogeneous population spanning two centuries.

This section presents empirical results of my analysis of mortality among the global IGO population 1815–2015. I first present descriptive statistics on IGO foundings and terminations. Next, I use proportional hazard analysis to compare the relative mortality of different kinds of IGOs in different settings. While previous studies have documented variation in IGO founding rates during different historical periods (Wallace and Singer 1970), or examined rates of organizational entry/exit from the IGO system during specific periods (Shanks et al. 1996; Abbott et al. 2016), or for specific kinds of organizations (Gray 2018), so far, none has studied rates of mortality/survival or examined variation in institutional design features across the population as a whole, from its inception to the present. My analysis thus adds empirical breadth to existing knowledge about IGO design and robustness.

Of 218 IGOs that have died since 1815, fifty-eight (27%) terminated through dissolution, while forty-eight (22%) disappeared through desuetude. Forty IGOs (19%) were absorbed by or merged with another organization, while 61 (28%) were replaced by a successor. Only four IGOs terminated due to their founding treaties expiring. In sum, the majority of IGO deaths resulted from an explicit decision by contracting states to terminate cooperation, whereas a smaller subset of IGOs (less than a quarter) were left to fade away through desuetude, or allowed to expire (Fig. 1).

Figure 2 depicts IGO births/deaths per decade since 1850.²¹ Despite a steady growth in the total number of IGOs in the system over time (shown by the upper, green curve), the figure reveals a high rate of organizational turnover, as existing IGOs have died in significant numbers, while new ones have been founded.

Figure 3 shows IGO deaths per decade since 1850 as a proportion of the population of IGOs in existence during each decade.²² The figure shows a significant spike in mortality-rates during the 1910s, 1930s and 1940s—coinciding with the two World Wars and the Great Depression. For example, eight IGOs terminated between 1910 and 1919 (equal to 19% of the incumbent population) compared to just one fatality during the previous decade. The 1930s and 1940s also had high mortality-rates (respectively 25% and 29% of the incumbent population).²³ Global mortality rates remained medium-high during the 1950s and 1960s with deaths mainly concentrated in Africa (see discussion below). Mortality-rates dipped worldwide during the 1970s and 1980s, only to rise again during the 1990s, when 18% of the incumbent population terminated in a single decade (compared to just 5% during the 1980s). Although new IGOs continued to be born during periods with high mortality, IGO founding-rates slowed markedly around the world wars and at the end of the Cold War, resulting in a negative growth-rate for the population during the periods 1905–1914, 1925–1944 and 1990–2000.²⁴ By contrast, the years immediately following each world war saw a sharp increase in new IGO births.

Table 1 shows the general results of my proportional hazard (PH) analysis, which measures variation in mortality rates across different subsets of the population. Like all PH models, the model relates the time that passes before a specific event occurs (in this case IGO termination) with various covariates that may be associated with that length of time. A PH analysis measures the unique effect of each co-variate on the hazard-rate, and is thus ideally suited to isolating the independent effects of different institutional design or contextual factors. For example, the model shows that being situated in a specific geographic region (say, Europe) increases an IGO’s hazard-rate for termination, while having a specific mandate (e.g., technical or scientific assistance) decreases the hazard-rate. The population at risk is the set of all IGOs in existence at any given time, while ‘fatalities’ or ‘hazards’ include all IGOs that terminate through either Expiry, Dissolution, Desuetude, Succession or Merger/Absorption within the specified time-frame.

Starting with the impact of Region, I find that IGOs with global membership have significantly lower hazard-rates than regional organizations (Table 1).²⁵ Among regional IGOs, the highest hazard-rates are among European organizations. Taking the hazard-ratio of global IGOs as a baseline, European IGOs are seven times more likely to terminate than global IGOs during the two centuries under scrutiny. African and American regional organizations are about six times more likely to terminate than global IGOs. Regional organizations in Asia and the Arab world have lower hazard-rates. However, as these regions have relatively small and young IGO populations, these findings are not statistically significant.²⁶

We can refine this picture by looking for variation in when mortality spiked across different regions. Figure 4 shows decadal mortality-ratios for different regions of the world. Mortality among European IGOs peaked between 1910 and 1919 (60%), and during the 1930s and 1940s when respectively 78% and 67% of the European IGO population terminated (compared to 25% and 29% globally). Mortality-rates remained high in Europe during the 1950s but dropped significantly between 1960 and 1990. As noted above, Africa experienced the highest mortality-rates during the 1950s (50%) and 1960s (60%), coinciding broadly with decolonization.²⁷ IGO mortality increased across all regions at the end of the Cold War.

Turning next to Mandate, the PH model shows hazard rates to vary significantly according to the types of problems IGOs address. The lowest hazards are among IGOs with technical or scientific focus, and IGOs with general purpose.²⁸ Social organizations also have low hazard ratios compared to economic organizations (the base-line group), while the highest hazard-rates are among security organizations.²⁹ The finding that security organizations have the highest hazard rates, however, is only significant in the model in which successions are treated as survivals. This makes intuitive sense, since we may speculate that security IGOs are more likely to terminate due to geopolitical events which undermine their very raison d’être (thus foreclosing continued cooperation on similar issues), while technical IGOs are more likely to succumb to demands for organizational reform, which for some reason cannot be achieved through standard reform procedures (See Klabbers 2011). In this latter case, continued demand for common solutions to technical problems may lead to continued cooperation within the framework of a new organization. Indeed, when examining how different kinds of IGOs terminate, I find that technical IGOs are more prone to terminate through succession or merger than other functional types. Security and economic IGOs, by contrast, tend to terminate through dissolution or desuetude (see Table 3, Appendix ). This lends support to the notion that security organizations often terminate because their services are no longer desired, whereas technical IGOs may terminate due to demands for functional re-organization (I discuss these findings in more detail in the concluding section).

In terms of Number, I find that a large membership lowers risk of termination. To capture the impact of Number, I have coded the number of member states for all IGOs at the beginning and end of their lifespan.³⁰ In all model specifications, the last recorded Number is a statistically strong predictor of termination, with an inverse correlation between Number and mortality so that having more members lowers risk of death. This finding must, however, be treated with caution, since it is plausible that successful IGOs attract more members over time whereas ineffective organizations lose members, implying that Number may be confounded with other survival enhancing factors such as, say, ‘organizational effectiveness’. Nonetheless, as I discuss in Part 3, there are several plausible theoretical explanations for why the size of an IGO’s membership—in and of itself—may lower IGO hazard-rates.

Looking at Membership I find that ‘inclusive’ IGOs have higher survivability than organizations that restrict membership according to either geographical or functional criteria. Most IGOs with inclusive membership, however, are also global in span, meaning that this variable may capture a mixed impact of its own variation and variation in the geographic Region variable (Fig. 5).

Having recorded the lifespans of individual IGOs allows me, lastly, to consider the impact of organizational age on survivability. Interestingly, I find that an IGO’s survival rate drops relatively rapidly during the first three decades of its life, then tails off after 30 years, only to stabilize at about 50 years of age. In other words, once an IGO makes it through a perilous youth during which it appears particularly vulnerable to failure (perhaps due to being poorly consolidated?) its prospects of survival improve. This might suggest that organizational survival is positively dependent on age, so that the older an IGO is the less likely it is to terminate.³¹ I discuss possible interpretations of this finding in Part 3 (Fig. 6).

My analysis so far has shown a clear correlation between geopolitical upheaval and IGO deaths. That IGO mortality-rates increase during periods of geopolitical turmoil is theoretically unsurprising. Whether one adopts a realist, rational institutionalist, or constructivist perspective, dramatic shocks to the international system, such as armed conflict, are expected to trigger institutional change—either as a direct result of changing balances of power and interest (Gilpin 1981:14; Ikenberry 2001:3), as a result of changing cost-benefit calculations (as new constellations of interest reduce the future expected benefits from present institutions), or as a result of normative contestation which “loosen(s) commitments to existing identities and behavioral norms”, thereby undermining the legitimacy and stability of existing institutions (Kowert and Legro 1996; Panke and Petersohn 2011). Nonetheless, while many IGOs have succumbed to geopolitical conflict since 1815, many more have survived. What, if anything, distinguishes ‘survivors’ from ‘casualties’?

The proportional hazard analysis presented in this part points to several possible ‘robustness enhancing’ factors (for example, large Number) which may boost an IGO’s survival prospects. Given the substantial variation in these factors across the population and across the time period under study, the best way to examine whether these features do in fact exert a protective effect during times of crisis is to directly compare the features of IGOs that survived a specific geopolitical shock to those that terminated. With this aim, this section briefly examines the effects of World War I on the global IGO population. Observing the effects of a large exogenous shock at a time when the global IGO population was still relatively young and geographically concentrated allows me to isolate the effects of specific institutional factors such as Number, Membership and Mandate, while holding constant other, possibly confounding, factors such as organizational age and historical founding moment.

As illustrated earlier, the global IGO population grew steadily during the nineteenth and early-twentieth century. Between 1815 and 1914, forty-eight IGOs were created worldwide, while just one terminated. On the eve of World War I, the global IGO population thus counted forty-seven organizations. Of these, nine terminated during the war (1914–1918), whilst another eight terminated within ten years of the Versailles Peace Settlement of 1919 (and thus within 10 years of the formal end of hostilities). Based on my definition of Desuetude (>10 years of inactivity), I treat all these as probable war casualties. By contrast, any IGO still functioning after 1929 is considered a survivor even if it subsequently terminates. These criteria yield sixteenfatalities and thirty-one survivors of World War I. (A list and description of these organizations is included in the Appendix). What, if anything, distinguishes the two categories?

The profiles of World War I fatalities support findings from my previous analysis. Most terminations occurred among regional IGOs in Europe. Between 1914 and 1929, European IGOs were more than four times as likely to terminate as IGOs with global membership (see Table 2). Similarly, IGOs with restricted membership were three times as likely to die as inclusive IGOs. In terms of mandate, the lowest hazard-ratios were once again among technical IGOs (11%) and among organizations focused on social issues (33%), while the highest hazard-rates were among IGOs focused on security, followed by economic and judicial cooperation (Table 2).³² Surviving IGOs had on average twice as many members as those that succumbed. Organizational age does not correlate with mortality during this period.³³

In sum, IGOs that survived the Great War mostly had wide geographic scope, large Number and technical focus. Having survived World War I, eighteen of thirty-one  ‘World War I veterans’ went on to also survive World War II, and fourteen are still alive today. As they have advanced in age, these IGOs have increased their Number from an average of eighteen members in 1914 to an average of 125 members in 2015, presumably further enhancing their robustness.

Space does not allow me to include a more detailed case study of these long surviving IGOs. However, a few observations stand out. It is noteworthy, for example, that long-term survivors mainly included organizations focused on narrow technical or administrative issues and with global membership. These included, inter alia, the International Telecommunication Union (1865), the Universal Postal Union (1874), the International Bureau of Weights and Measures (1875), the International Union for Protection of Industrial Property (1883), the International Union for Publication of Customs Tariffs (1890), and the World Road Association (1908). Established to enhance international interoperability by standardizing postal rates, radio communication and road signs, these organizations were of great practical value but had limited geopolitical consequences.

Some technical organizations did succumb to the war. An example is the International Secretariat for the Unification of Pharmacological Terms (ISUPT). Founded in 1902 to standardize drugs terminology, ISUPT membership was in principle open to all countries. However, at the time World War I broke out, ISUPT's membership was still limited to nine contracting parties, including the USA and eight West European states. As the war limited opportunities for travel and reduced funding, ISUPT’s activities soon ground to a halt. Efforts to standardize drug terminology were, however,  renewed during the interwar period, and the functions envisaged for ISUPT eventually came to be fulfilled by the WHO after 1948. In this case, the fact that conflict broke when ISUPT was still newly established and poorly consolidated thus may have played a significant role in its demise.

Since geographic span and location appear crucial to organizational survivability during times of geopolitical upheaval, it is instructive to look more closely at European-based regional IGOs. Only three European organizations survived World War I. One was the International Conference for Promoting the Technical Unification of the Railways (founded 1882). Despite focusing on a seemingly technical issue (ensuring uniformity in rolling stock exchange to ease railway transport across the Continent) this organization was strongly politicized due to the nature of the war effort, which involved large-scale mobilization of troops by rail. Whilst it survived the war on paper, and even expanded its membership, the struggle between Germany and France for dominance of the Conference meant that the conference was practically deadlocked after 1914, and it dissolved in 1938.

The two remaining European survivors were the Commissions for control of navigation on the Danube and Rhine rivers. Designed to keep open the European waterways to trade, both organizations were geopolitically highly significant. Importantly, both were founded many decades (or, in the case of the Rhine Commission, a full century) before the 'great war', and both had high levels of organizational autonomy, possessing strong mechanisms for influencing state behavior. For example, the Danube Commission had powers to borrow money on private markets, and maintained an independent treasury by collecting dues from ships. It also issued regulations with binding effect without direct approval by member states. Similarly, the Rhine Commission issued detailed regulations for navigation on the Rhine, which were transposed into national law by member states. Both commissions maintained their own vessels and undertook large scale projects to keep the rivers open, clean and navigable. In short, they provided crucial services that could not be easily replaced. Given the strong interest of governments in defending national shipping interests, the river commissions were integral parts of earlier geopolitical settlements (The Vienna Peace Treaty of 1815, and the Paris Peace Treaty of 1856). With the end of World War I both commissions now became part of the new Versailles system. To reflect the new geopolitical reality, Russia, Austria, Germany and Turkey were ousted from the Danube Commission. The Rhine Commission’s headquarters were moved from Mannheim to Strasbourg, and France (which had lost its status as a riparian state in 1870–71) was readmitted together with Belgium, Italy and Britain. Ultimately, then, membership was fundamentally refashioned to reflect a new distribution of power and interests. It seems plausible, however, that the considerable authority and practical expertise vested in the river commissions played a large part in enabling them to survive as organizational entities rather than being dissolved to make way for new cooperative arrangements.

The analysis in Part 2 shows that large Number, wide geographic span, and advanced age increase IGO robustness. Additionally, IGOs serving technical or scientific functions are more robust than other types. To be sure, these factors may be partly interrelated; with higher age comes more members (and thus wider geographic span). Nevertheless, each factor asserts an independent, positive effect on IGO survivability in the PH model. A good way to think of these features is thus as ‘probability raisers' (Mahoney 2008:7, 13)³⁴; none of these factors appear either necessary or sufficient to ensure the survival of an IGO, but individually and in combination they enhance its overall resilience.

Combined these findings describe a global IGO system in which positive feedback and institutional lock-in dominates, so younger and smaller IGOs are at higher risk of death, while increasing age and size reduce failure-rates, allowing established IGOs to grow yet older and larger.³⁵ Much like economic markets dominated by firms (see Ranger-Moore 1997:904), such a system is likely to grant clear advantages to ‘first-comers’ that can exploit low initial rates of competition in a given area to establish a dominant position from which they can continue to expand. Theoretically, this system is thus likely to feature a relatively stable core of long-established IGOs, combined with frequent entry and exit of new organizations on the margins.

This picture contrasts sharply to what we might describe as a ‘perfectly competitive’ IGO marketplace. In a perfectly competitive market, changing market conditions combined with high costs of institutional reform would likely cause older and larger IGOs to gradually succumb to growing organizational inertia and historical anachronism. Rather than displaying a stable core of long-established institutions, such a system would likely be characterized by constant institutional turnover, as older and less flexible IGOs were abolished and replaced by newcomers better fit-for-purpose. As my analysis has shown, the global IGO-system since 1815 most closely resembles the former kind of system.

The present study points to several avenues for future research. First, important questions arise from the large number of institutional successions documented. As discussed in Part 1, a large swathe of institutionalist literature cites high costs of institution-building and increasing returns to cooperation as weighty reasons why states prefer to reshape or reform existing institutions rather than accept the costs and uncertainties associated with creating new ones (Keohane 1984:102; Abbott et al. 2016; Kahler 2009; Johnson and Urpelainen 2012). Some scholars go even further, suggesting that “paths of action taken by actors or institutions can be virtually impossible to reverse” (Pierson 2000:251). Against such expectations, my analysis shows that states have repeatedly chosen to dismantle existing institutions and to start over from scratch - negotiating new rules of cooperation and creating new organizations to oversee their implementation. This does not imply that institutional theories based on path-dependence or institutional lock-on are wrong, merely that they may be overstating the strength of the forces preventing existing institutions from being replaced. Furthermore, my analysis suggests that the scope conditions of such theories need to be more sharply defined. Institutional path-dependence does not necessarily imply IGO endurance. Presumably, path-dependent processes may ocassionally lead to dead-ends, as barriers to institutional reform mean that international organizations fail to adapt to exogenous change.³⁶ The conditions under which specific dynamics of path-dependence may hinder IGO dismissal thus need more careful specification. A promising place to start would be to study more closely the many historical cases of institutional succession identified in this article. Under what conditions have states chosen to replace extant IGOs? Considering that institutional successions involve significant changes to either an IGO’s membership, mandate or decision-rules, a plausible hypothesis might be that successions provide a means to escape ‘joint decision traps’ (Pierson 1996) due to which disobliging members may prevent desired institutional reforms. Another theoretic possibility is that institutional successions represent instances of re-contracting between state ‘principals’ and IGO ‘agents’, perhaps in order to reduce agent slack. Such hypotheses can be best explored through more detailed post-mortem case-studies, which would allow us to pose what Gryniviski (2013) calls ‘contrastive why questions’. ^‘Why succession rather than institutional reform?’ Exploring this question in a historical context may cast new theoretical and empirical light on processes of institutional change.

Another topic for future research concerns the role of organizational agency. A population-oriented approach to organizational change such as the one adopted here focuses on explaining macro-level changes in the number and types of IGOs but does not consider questions of individual organizational adaptation. Macro-level changes are understood to occur, not through organizational-level adaptation, but through a process of ‘competitive selection’ whereby an environment rewards certain traits and punishes others (see Hannan and Freeman 1977; Halpin and Jordan 2009). This downplays the importance of individual agency whereby IGO actors react to environmental stimuli and seek to refashion themselves to avoid obsolescence (see Johnson 2013; Abbott et al. 2016). A more actor-centric approach might instead consider how an IGO’s capacity for autonomous action affects its survival chances. For example, Gray (2018) shows that the vitality of international trade organizations hinges on the quality of their bureaucracy and the ability of secretariats to enact policy autonomously. Examining the role of autonomous agency by IGO bureaucracies is beyond the scope of this article. However, the findings presented here may serve as a starting-point for a case-study based analysis of strategic adaptation by IGOs—for example by pointing to ‘outlier’ cases in which agent-driven adaptation may have played a decisive role in ensuring survival.

A third avenue for future research concerns possible variation in the determinants of IGO survivability across time. Unlike previous studies of IGO vitality (Gray 2018) or permanency (Shanks et al. 1996), the present study analyzes the entire population of IGOs created since 1815. This is both a strength and a weakness. The benefit of a broad historical approach is that it yields more observations, thus lending greater confidence to statistical findings. On the other hand, by analyzing patterns of IGO death/survival across two centuries, I implicitly presuppose that the determinants of IGO survivability remain relatively constant over time. This may not be the case. After all, the global IGO population has undergone profound changes since 1815. Crucially, there has been a significant increase in the total number of IGOs, combined with the emergence of new kinds of international organizations, such as transgovernmental organizations, public-private partnerships, and private transnational regulatory bodies (Abbott et al. 2016). Such changes may trigger new processes of ecological change. Specifically, growing numbers of organizations with a similar focus and overlapping membership are likely to lead to a more competitive environment, as growing ‘institutional density’ (or what some International Relations scholars refer to as ‘regime complexity’) intensifies competition for resources (Abbott et al. 2016; Hannan and Freeman 1989:132–33). In such an environment, some IGOs may dissolve, not due to specific environmental shocks, but rather because the existence of other organizations with similar purpose and membership means they lose out on vital resources including access to expertise and state funding. This might explain the high mortality-rates at the beginning of the twenty-first century, a period of relative geopolitical stability. Whether the determinants of IGO mortality vary across time is a question for future research which might be explored by dividing the general IGO population into separate historical sub-populations and examining patterns of mortality/survivability for each in turn.

An important aim of this study has been to demonstrate that the historical population of defunct IGOs constitutes a rich (but relatively untapped) source of empirical data against which theoretical expectations regarding the robustness and effectiveness of IGOs can be evaluated and refined. Future research should derive explicit hypotheses regarding the death/survival of different forms of IGOs and code relevant aspects of the population to enable systematic hypothesis testing. Although it has been beyond the scope of this article to test any specific theory of IGO death/survival, I hope to have indicated the kinds of questions that a rigorous social scientific research agenda on IGO ecology could seek to answer, using a combination of statistical analysis and qualitative research, including more detailed post-mortem case studies of deceased IGOs.