Nathan Sears: “… in the midst of catastrophe”

Nathan Sears had begun a strikingly ambitious intellectual project of reimagining international relations and world order, almost from the ground up. Nathan saw that we were in a new era of human history, an era of existential risk. We face threats of global civilisation collapse, possibly even human extinction, of our own making. These anthropogenic risks include nuclear weapons, biological weapons— especially new engineered pandemics— environmental risks such as climate change and risks from emerging technologies, such as artificial general intelligence (AGI). As Nathan saw it, this new era should pose profound challenges to traditional ways of thinking about and doing international relations (IR; Sears, 2020a). Instead of ‘human security’ of individual citizens or ‘national security’ of individual states, we must now also be concerned with ‘existential security’ of the whole of humanity. Instead of thinking of army divisions or status games when ascertaining Great Powers, we must now ask, ‘who can destroy the world?’. The old Westphalian order struggles to make sense of this new order. The old units of states and alliances, the old methods of war and balance of power and the old ideologies of selfhelp and power politics are inadequate for comprehending this new era. Nathan's work took seriously the challenge existential risks pose to existing theories of international relations. He gazed directly into the abyss of civilisational collapse and human extinction and sought to reimagine rationalism, neorealism and securitisation theory within this frame. Nathan's work on international relations and existential risk had just scratched the surface of a substantial, novel challenge to the theory and practice of global politics. I'd like to highlight the influence of his work on the study of existential risk, especially at my own Centre for the Study of Existential Risk (CSER) at the University of Cambridge. I met Nathan in 2019. At that time, we were planning a panel on ‘Global Governance and Existential Risk’ in Canada, another panel on ‘Catastrophic and Existential Threats and World Orders’ for the International Studies Association conference in Honolulu, and arranging for Nathan to visit us at CSER, all in .... March 2020. Needless to say, that was all scrapped by an extreme risk we had both worked on but hadn’t predicted: the COVID19 pandemic. As usual, Nathan had a fascinating and insightful take, noting how “this is all testing our assumptions about the durability/vulnerability of our social systems. Apparently – and, I think, against the expectations of many – we don't need millions dead to put serious pressure on social systems”. He suggested a need for further research exploring “the social and political dynamics of durability and vulnerability in the midst of catastrophe”. Despite the COVID19 pandemic, Nathan was able to remotely present his paper on ‘existential security’ to us in May 2020 (Sears, 2020b). It provoked a great deal of debate about the opportunities and risks of securitisation theory. Securitisation is a powerful political move that takes an issue out of the arena of normal politics and justifies extraordinary action. This may be important, even necessary, to motivate action and international cooperation. But it is also a dangerous move that could be used to justify illegitimate or counterproductive policies. His work provoked extensive debate and indeed, even a draft paper disagreeing with him. What better tribute can be paid to a researcher than deep, critical engagement with their work? Another of his papers posed the question ‘Which states possess the material capacity to destroy Received: 4 August 2023 | Accepted: 8 August 2023

Nathan Sears had begun a strikingly ambitious intellectual project of reimagining international relations and world order, almost from the ground up.
Nathan saw that we were in a new era of human history, an era of existential risk.We face threats of global civilisation collapse, possibly even human extinction, of our own making.These anthropogenic risks include nuclear weapons, biological weapons-especially new engineered pandemics-environmental risks such as climate change and risks from emerging technologies, such as artificial general intelligence (AGI).
As Nathan saw it, this new era should pose profound challenges to traditional ways of thinking about and doing international relations (IR; Sears, 2020a).Instead of 'human security' of individual citizens or 'national security' of individual states, we must now also be concerned with 'existential security' of the whole of humanity.Instead of thinking of army divisions or status games when ascertaining Great Powers, we must now ask, 'who can destroy the world?'.The old Westphalian order struggles to make sense of this new order.The old units of states and alliances, the old methods of war and balance of power and the old ideologies of self-help and power politics are inadequate for comprehending this new era.Nathan's work took seriously the challenge existential risks pose to existing theories of international relations.He gazed directly into the abyss of civilisational collapse and human extinction and sought to reimagine rationalism, neorealism and securitisation theory within this frame.
Nathan's work on international relations and existential risk had just scratched the surface of a substantial, novel challenge to the theory and practice of global politics.I'd like to highlight the influence of his work on the study of existential risk, especially at my own Centre for the Study of Existential Risk (CSER) at the University of Cambridge.
I met Nathan in 2019.At that time, we were planning a panel on 'Global Governance and Existential Risk' in Canada, another panel on 'Catastrophic and Existential Threats and World Orders' for the International Studies Association conference in Honolulu, and arranging for Nathan to visit us at CSER, all in ….March 2020.Needless to say, that was all scrapped by an extreme risk we had both worked on but hadn't predicted: the COVID-19 pandemic.As usual, Nathan had a fascinating and insightful take, noting how "this is all testing our assumptions about the durability/vulnerability of our social systems.Apparently -and, I think, against the expectations of many -we don't need millions dead to put serious pressure on social systems".He suggested a need for further research exploring "the social and political dynamics of durability and vulnerability in the midst of catastrophe".
Despite the COVID-19 pandemic, Nathan was able to remotely present his paper on 'existential security' to us in May 2020 (Sears, 2020b).It provoked a great deal of debate about the opportunities and risks of securitisation theory.Securitisation is a powerful political move that takes an issue out of the arena of normal politics and justifies extraordinary action.This may be important, even necessary, to motivate action and international cooperation.But it is also a dangerous move that could be used to justify illegitimate or counterproductive policies.His work provoked extensive debate and indeed, even a draft paper disagreeing with him.What better tribute can be paid to a researcher than deep, critical engagement with their work?
Another of his papers posed the question 'Which states possess the material capacity to destroy humanity?' (Sears, 2021).That is, who exactly is it that is contributing to existential risk?His answer was the United States, Russia and China-and for this reason, these three should be considered the Great Powers.This too has prompted further research addressing both the physicality of existential risk-the creation, location and ownership of the material capabilities of destruction (Belfield & Hua, 2022;Mani et al., 2021)and its political economy (Kemp, 2021): who is creating existential risk and in whose interest?
In early 2023, Nathan had finished his PhD in Political Science and was looking to turn his dissertation into a book project (Sears, 2022).It was already causing discussion and debate at CSER, and I was hoping to lure him over to Cambridge to work together.Never out of ideas, Nathan was already proposing a paper titled 'Artificial Intelligence and the Tragedy of Great Power Politics: The "Superintelligence" and "Doomsday Machine" Scenarios'.What might he have made of current concerns about artificial intelligence (AI)?How might he have contributed to cutting-edge policy debates about an 'International Atomic Energy Agency (IAEA) for AI'?
In his thesis, Nathan posed an excellent puzzle: why have the Great Powers come to agree that some issues constitute an existential threat and necessitate extraordinary action-such as nuclear proliferation, biological weapons or nuclear winter-but not others-such as international control over atomic energy, climate change, nuclear prohibition, artificial intelligence or biodiversity loss?Had we more time, I would have pushed him on some of these issues.Should the Biological Weapons Convention really be counted as a success when the Soviets cheated and launched the largest biological weapons programme ever, indeed the only one to have a capacity close to nuclear weapons (Carus, 2017)?Isn't international control of anti-ballistic missiles an excellent example of great power consensus and cooperation (Adler, 1992)?I would have enjoyed arguing with him about these topics.
Looking forward to where Nathan's scholarship might have gone, I'm struck by a conversation we had in September 2020.He was moved to share with me the excellent article 'Worlding beyond "the" "end" of "the world": white apocalyptic visions and BIPOC futurisms' (Mitchell & Chaudhury, 2020).In his reflections, he grappled with what he saw in his own bibliographies, populated by 'mostly white Anglo men like myself'.He was also intrigued by the epistemological critique in the article about science and scientists and the call to be more inclusive of more traditional ways of knowing, as well as art, cinema, novels, etc.Reflecting on the field of existential risk, he noted with criticism how its focus on the future (e.g. the 'far future' argument, multigenerational ethics and critique of 'short-termism') could lead it to discount the present, including the survival practices of indigenous societies against the threat of genocide and disappearance.
For his own work, he found the paper prompted him to reflect on issues of racism and inequity and how these might emerge in global conceptions of 'humanity'.In his own words, he asked: What constitutes "humanity"?This is an interesting theoretical question that, as the article makes clear, may be biased by systemic racism.As Robert Cox once wrote, theory is always by some person and for some purpose.The question becomes "who defines 'humanity' and for what ends?" … My own work is guilty of papering-over difference in the aim of "creating humanity".Different communities may prioritize different threats and imagine different means of response.Thinking about "existential risk" as a "global priority" demands a truly global discussion.
The field of existential risk is still grappling with these issues that Nathan reflected upon so early and with such humility (Cremer & Kemp, 2021;Sundaram et al., 2022).
What could Nathan have gone on to do? Motivated by the desire to make a difference on these crucial issues, but hooked on research and teaching, I imagine he would have sought to combine academia and public service.In fact, he had already begun to play these dual roles, working for the Foreign Policy Research and Foresight Division of Global Affairs Canada while he completed his dissertation.When I read his work, I'm reminded of the preface to 'Nuclear Weapons and Foreign Policy', Kissinger's first book, in which he argues: "Mankind has as its disposal the means to destroy itself at the precise moment when schisms among nations have never been deeper […] Foreign policy henceforth will have to be framed against the background of [this] world" (Kissinger, 1957).
Could Nathan have been a scholar and a statesman?Our field, his nation and the world are poorer for not having the opportunity to know the answer to that question.
Nathan has left us a powerful inspiration and guide to action.It would honour his legacy to do what we can to persuade the Great Powers that these risks are real and that they require extraordinary action.States should put aside temporary advantage and collaborate on reducing the risks we all face together.I will remember, and try to pass on, his wisdom in seeing that national survival requires humanity's survival; that existential security is national security.

ACK NO WLE D GE M ENT S
I would like to thank the editors and Nathan's family for bringing this special issue together.