Longtermism, Existential Risk, and Global Priorities

Thinking Deeply About What Matters Most

When we try to decide how to spend our time, money, or influence, we often fall back on intuition: help those in front of us, support familiar causes, or follow what feels urgent. But what if the most important actions are not the most visible ones? What if the biggest moral stakes lie not in the next few years, but in the next few centuries or millennia?

These questions sit at the heart of a growing area of academic work that blends philosophy, economics, and decision theory to ask: How should we set global priorities? How can we use evidence and reason to figure out which problems are most pressing and which interventions are most promising? At the center of this effort is the Global Priorities Institute (GPI) at the University of Oxford, and one of its key figures is philosopher Hilary Greaves.

From Coffee Shops to the Far Future

Imagine a simple moment: you’re handed back too little change at a café. Do you go back and correct the mistake, or let it go? On the surface, this is a small ethical puzzle. But from a certain philosophical perspective, it’s a window into a much larger idea: that even tiny actions can have vast, unpredictable ripple effects over time.

Greaves uses this kind of example to illustrate a concept sometimes called moral cluelessness. The idea is that when we act, we set in motion a chain of events that alters who will exist in the future. Because people’s identities depend on specific historical conditions, even a small change in timing or circumstance can mean that different people are born. Over generations, this can lead to a completely different set of future people.

This doesn’t mean we should paralyze ourselves with indecision. But it does suggest that when we’re trying to do the most good, we can’t just focus on the immediate, visible effects of our actions. We also have to grapple with the fact that our choices shape the long-term trajectory of humanity in ways we can’t fully predict.

Why the Long-Term Future Matters

One of the most striking ideas that has emerged from this line of thinking is longtermism: the view that positively influencing the long-term future is a key moral priority of our time.

Longtermism rests on a few core claims:

• Humanity could survive for a very long time, potentially millions or billions of years.
• The quality of that future could vary enormously: it could be extraordinarily good, or it could be filled with suffering and premature extinction.
• Our generation has some ability to influence which of these paths we take.

If these claims are even roughly correct, then the expected value of actions that reduce the risk of human extinction or lock in a better long-term trajectory can be enormous. Even a tiny reduction in the probability of extinction could, in expectation, save vast numbers of future lives.

This doesn’t mean that all longtermist efforts must focus on extinction risk. It also includes improving institutions, values, and technologies in ways that make a better long-term future more likely. But it does suggest that when we’re trying to do the most good, we should pay special attention to interventions that affect the long-run shape of civilization.

Minimal vs. Expansive Longtermism

Not all versions of longtermism make equally strong claims. Philosophers have distinguished between minimal and expansive forms of longtermism.

Minimal longtermism is the relatively modest claim that it is extremely important, for reasons concerning the far future, that key decision-makers (such as major philanthropists, talented career choosers, and some policymakers) direct significantly more resources toward reducing existential risks and otherwise improving the long-term trajectory of humanity.

Expansive longtermism goes further, suggesting that the long-term future should dominate our moral calculations to the point where near-term benefits are almost negligible in comparison. This stronger version is more controversial and faces more philosophical objections.

The distinction matters because it helps clarify what is most defensible. Even if we’re not convinced by the strongest forms of longtermism, we might still accept that the long-term future is so important that it should be a major consideration in how we set priorities.

Cluelessness and the Limits of Prediction

One of the deepest challenges in this area is what Greaves calls moral cluelessness: the idea that for many of our actions, we are radically uncertain about their long-term effects.

Consider a policy that boosts economic growth. In the short term, we might be able to estimate its effects on poverty, health, and inequality. But over the long term, it could affect technological development, political stability, environmental degradation, and even the risk of conflict or extinction. The net effect could be positive, negative, or neutral, and we may not have enough information to assign confident probabilities to these outcomes.

This raises a hard question: if we’re clueless about the long-term effects of our actions, how can we claim to know which ones are best? One response is to focus on actions where we do have relatively robust reasons to think they will have a positive long-term impact. For example, reducing the risk of nuclear war, improving biosecurity, or advancing AI safety might be cases where we can identify a clear, systematic tendency for the action to make things better, even if we can’t predict all the details.

How to Think About Global Priorities

The Global Priorities Institute was created to develop this kind of thinking within academia. Its mission is to conduct rigorous, foundational research on how to most effectively do good, with the goal of helping individuals and institutions make better decisions about where to focus their efforts.

Some of the key questions GPI and related work explore include:

• How should we compare the value of helping people today versus reducing risks to future generations?
• How should we handle moral uncertainty, when we’re unsure which ethical theory is correct?
• What does it mean for a policy or intervention to be “cost-effective” when we care about long-term effects?
• How can we improve our ability to forecast the long-term consequences of our actions?

These are not just abstract philosophical puzzles. They have real implications for how governments, foundations, and individuals allocate resources. For example, if longtermism is correct, then a much larger share of philanthropic funding might be justified in going toward existential risk reduction rather than near-term poverty alleviation, even if the latter feels more urgent or emotionally compelling.

Existential Risk and the Case for Prevention

One of the most concrete applications of this framework is in the area of existential risk: events that could permanently destroy humanity’s potential, such as nuclear war, uncontrolled artificial intelligence, engineered pandemics, or extreme climate change.

Philosophers and economists working in this space argue that even if the annual probability of such a catastrophe is low, the expected harm is enormous because it would cut short the potential of all future generations. This makes prevention unusually cost-effective, in expectation, compared to many other interventions.

For example, improving global health systems so that they can detect and respond quickly to emerging pandemics might seem like a near-term health intervention. But from a longtermist perspective, it’s also a way of reducing the risk of a pandemic that could spiral into a global catastrophe. Similarly, investing in AI safety research is not just about making current systems more reliable; it’s about reducing the risk that future, more powerful systems could cause irreversible harm.

Population Ethics and the Value of Future Lives

Underlying much of this work is a set of deep questions in population ethics: How should we weigh the interests of people who don’t yet exist? Is it better to have a larger population with a lower average quality of life, or a smaller population with a higher average? What is the moral significance of bringing new people into existence?

These questions are not just theoretical. They affect how we think about climate change, economic growth, and even space settlement. For instance, if we believe that creating more happy lives is a good thing, then expanding human civilization to other planets might be seen as a major moral opportunity. But if we are more cautious about creating new people, especially in uncertain or risky conditions, we might prioritize safety and stability over expansion.

Greaves and others have worked to clarify these issues, showing that many plausible moral theories—whether utilitarian, prioritarian, or egalitarian—end up placing substantial weight on the well-being of future people, even if they don’t all agree on exactly how to count them.

From Theory to Practice: What Should We Do?

So what does all this mean for how we should live and act?

One implication is that we should be open to the idea that the most important problems are not the ones that dominate headlines or social media. They might be less visible, more technical, and require long-term thinking. This doesn’t mean we should ignore near-term suffering, but it does suggest that we should be willing to redirect some of our resources toward long-term trajectory changes.

Another implication is that we need better tools for decision-making under uncertainty. This includes:

• Improving long-term forecasting and scenario planning.
• Developing better models of how different interventions affect existential risk.
• Creating institutions that are better at learning from evidence and updating their priorities.

Finally, it suggests that philosophy and economics have an important role to play in public policy and philanthropy. By clarifying concepts, identifying trade-offs, and developing rigorous frameworks for comparison, they can help ensure that our efforts to do good are as effective as possible.

Key Areas of Global Priorities Research

Work in global priorities often focuses on a few broad categories of interventions:

Frequently Asked Questions

What is the Global Priorities Institute?

The Global Priorities Institute (GPI) is a research center at the University of Oxford that aims to develop rigorous, foundational research on how to most effectively do good. It focuses on questions in philosophy, economics, and decision theory that are relevant to setting global priorities, especially in the context of longtermism and existential risk.

What is longtermism?

Longtermism is the view that positively influencing the long-term future is a key moral priority of our time. It emphasizes that humanity could have a very long future, and that our actions today can significantly affect whether that future is good or bad. This makes reducing existential risks and improving long-term trajectory changes especially important.

What is moral cluelessness?

Moral cluelessness is the idea that for many of our actions, we are radically uncertain about their long-term effects. Because small changes can alter who exists in the future, and because long-term consequences are hard to predict, we may lack confident beliefs about which actions are best. This challenges simple cost-benefit thinking and calls for more sophisticated decision frameworks.

Does longtermism mean we should ignore near-term problems?

No. Longtermism does not require ignoring near-term suffering. Many longtermist interventions also have near-term benefits (e.g., pandemic preparedness, improving health systems). The point is that when we’re trying to do the most good, we should give substantial weight to the long-term effects of our actions, not just their immediate impact.

How can individuals apply this thinking?

Individuals can apply this thinking by:

• Considering how their career, donations, and advocacy might affect the long-term trajectory of humanity.
• Supporting research and institutions that improve our ability to make good long-term decisions.
• Being open to the idea that the most important problems may not be the most visible ones.

Written by

Sneha Tete

• Integrated M.A. in Applied Linguistics, University of Hyderabad
• 5+ years in editorial, instructional, SEO, and research-based writing

Sneha is a relationships and lifestyle writer with a strong foundation in applied linguistics and certified training in relationship coaching. She brings over five years of writing experience to theskillvault,  crafting thoughtful, research-driven content that empowers readers to build healthier relationships, boost emotional well-being, and embrace holistic living. Her writing and insights reflect the belief that beauty, happiness, and wellness…