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Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: Modelling Great Power conflict as an existential risk factor, published by Stephen Clare on February 3, 2022 on The Effective Altruism Forum. This is the first post in a planned three-part series. Overview of the Series Conflict between Great Power states—countries with global interests and the military strength to defend them against their rivals—has shaped the course of history. The Napoleonic Wars redrew the borders of Europe. The League of Nations, created in the aftermath of World War I, foreshadowed the structure of today's international world order. World War II allowed the United States and the Soviet Union to emerge as dueling superpowers. The resultant Cold War sparked ideological conflicts around the world, accelerated the development of technology like rocketry and computers, and led to the growth of stockpiles of thousands of nuclear weapons. And, of course, each of these conflicts led to fighting around the world that caused hundreds of thousands or millions of casualties. Over the last year I’ve been thinking about the influence Great Power conflict will play in the 21st century. From a longterm perspective, I've been particularly focused on its influence as an existential risk factor: something that affects multiple other existential risks. This is the first post in a planned three-part series summarizing my current views. The series tackles three broad questions: Post 1: By what mechanisms does tension between Great Powers affect total existential risk? Post 2: How likely are various scenarios, including all-out war, this century? Post 3: What, if anything, can we do to make good outcomes more likely and bad outcomes less likely? Working through these questions, I updated my views a lot. My most important updates were: My estimate of the likelihood of a World War-type conflict between Great Powers increased. My current best guess is that, between now and 2100, we face a ~35% chance of a serious, direct conflict between Great Powers, a ~10% chance of a war causing more deaths than World War II, and 0.1% to 1% chance of an extinction-level war. I previously put more stock in the argument that humanity had experienced a sudden, dramatic, and lasting decline in the likelihood of conflict after World War II. My estimate of how bad such a war would be if it occurred increased significantly. While I find it intuitively hard to imagine how a war could grow to be worse than World War II, the long-tailed distribution of deaths per war makes it difficult to rule out extreme outcomes. I think there’s about a 1% to 2% chance of an existential disaster due to Great Power war before 2100. I’ve generated this number by disaggregating several specific pathways. I think the range of possible outcomes is broader than I previously believed. I updated away from thinking that conflicts are overdetermined, at least on sufficiently long timescales. It seems to me that the geopolitical possibilities for the 21st century range from devastating hot war to renewed cooperation between Great Powers. Where we end up landing on this spectrum will be influenced by policy choices made by leaders of Great Power states, and it is possible to influence these policies. There were also some other important things about which I learned a lot, but didn’t change my views as much: I’m still uncertain about how the average annual probability of Great Power conflict changed after World War II (if at all). Because the timing and size of wars is very noisy, the “Long Peace” that has prevailed since 1945 is consistent with two main models: A model in which there is a consistent risk of war, but large wars are rare. A model in which the probability of war fell significantly after World War II due to globalization, the spread of liberal norms, democratization, nuclear weapons, or some other factor. ...