Comparing the number of human lives in the past and present

Longtermism is the ethical view that positively influencing the long-term future is a key moral priority of our time.[1] It is an important concept in effective altruism and serves as a primary motivation for efforts that claim to reduce existential risks to humanity.[1]

The key argument for longtermism has been summarized as follows: "future people matter morally just as much as people alive today; ... there may well be more people alive in the future than there are in the present or have been in the past; and ... we can positively affect future peoples' lives."[2] These three ideas taken together suggest, to those advocating longtermism, that it is the responsibility of those living now to ensure that future generations get to survive and flourish.[3]


Philosopher William MacAskill defines longtermism in his book What We Owe the Future as "the view that positively influencing the longterm future is a key moral priority of our time".[4]: 4  He distinguishes it from strong longtermism, "the view that positively influencing the longterm future is the key moral priority of our time".[5]

In his book The Precipice: Existential Risk and the Future of Humanity, philosopher Toby Ord describes longtermism as follows: "longtermism ... is especially concerned with the impacts of our actions upon the longterm future. It takes seriously the fact that our own generation is but one page in a much longer story, and that our most important role may be how we shape—or fail to shape—that story. Working to safeguard humanity's potential is one avenue for such a lasting impact and there may be others too."[6]: 52–53  In addition, Ord notes that "longtermism is animated by a moral re-orientation toward the vast future that existential risks threaten to foreclose."[6]: 52–53 

Because it is generally infeasible to use traditional research techniques such as randomized controlled trials to analyze existential risks, researchers such as Nick Bostrom have used methods such as expert opinion elicitation to estimate their importance.[7] Ord offered probability estimates for a number of existential risks in The Precipice.[6]: 167 


The term "longtermism" was coined around 2017 by Oxford philosophers William MacAskill and Toby Ord. The view draws inspiration from the work of Nick Bostrom, Nick Beckstead, and others.[5] While its coinage is relatively new, some aspects of longtermism have been thought about for centuries. The oral constitution of the Iroquois Confederacy, the Gayanashagowa, encourages all decision-making to “have always in view not only the present but also the coming generations”.[8] This has been interpreted to mean that decisions should be made so as to be of benefit to the seventh generation in the future.[9] These ideas have re-emerged in contemporary thought with thinkers such as Derek Parfit in his 1984 book Reasons and Persons, and Jonathan Schell in his 1982 book The Fate of the Earth.


Longtermist ideas have given rise to a community of individuals and organizations working to protect the interests of future generations.[10] Organizations working on longtermist topics include Cambridge University's Centre for the Study of Existential Risk,[11] Oxford University's Future of Humanity Institute[12] and Global Priorities Institute, 80,000 Hours,[13] Open Philanthropy,[14] the Future of Life Institute,[15] The Forethought Foundation,[16] and Longview Philanthropy.[17]

Implications for action

Researchers studying longtermism believe that we can improve the long-term future in two ways: "by averting permanent catastrophes, thereby ensuring civilisation’s survival; or by changing civilisation’s trajectory to make it better while it lasts. Broadly, ensuring survival increases the quantity of future life; trajectory changes increase its quality".[4]: 35–36 [18]

Existential risks

Main articles: Global catastrophic risk and Global catastrophe scenarios

An existential risk is "a risk that threatens the destruction of humanity’s longterm potential",[6]: 59  including risks which cause human extinction or permanent societal collapse. Examples of these risks include nuclear war, natural and engineered pandemics, Climate change and civilizational collapse, stable global totalitarianism, and emerging technologies like artificial intelligence and nanotechnology.[6]: 213–214  Reducing any of these risks may significantly improve the future over long timescales by increasing the number and quality of future lives.[18][19] Consequently, advocates of longtermism argue that humanity is at a crucial moment in its history where the choices made this century may shape its entire future.[6]: 3–4 

Proponents of longtermism have pointed out that humanity spends less than 0.001% of the gross world product annually on longtermist causes (i.e., activities explicitly meant to positively influence the long-term future of humanity).[20] This is less than 5% of the amount that is spent annually on ice cream in the U.S., leading Toby Ord to argue that humanity “start by spending more on protecting our future than we do on ice cream, and decide where to go from there”.[6]: 58, 63 

Trajectory changes

Existential risks are extreme examples of what researchers call a "trajectory change".[18] However, there might be other ways to positively influence how the future will unfold. Economist Tyler Cowen argues that increasing the rate of economic growth is a top moral priority because it will make future generations wealthier.[21] Other researchers think that improving institutions like national governments and international governance bodies could bring about positive trajectory changes.[22]

Another way to bring about a trajectory change is by changing societal values.[23] William MacAskill argues that humanity should not expect positive value changes to come about by default.[24] For example, most historians now believe that the abolition of slavery was not morally or economically inevitable.[25] Christopher Leslie Brown instead argues in his 2006 book Moral Capital that a moral revolution made slavery unacceptable at a time when it was otherwise still hugely profitable.[25] MacAskill argues that abolition may be a turning point in the entirety of human history, with the practice unlikely to return.[24] For this reason, bringing about positive value changes in society may be one way in which the present generation can positively influence the long-run future.

Living at a pivotal time

Longtermists argue that we live at a pivotal moment in human history. Derek Parfit wrote that we "live during the hinge of history"[26] and William MacAskill states that "the world’s long-run fate depends in part on the choices we make in our lifetimes"[4]: 6  since "society has not yet settled down into a stable state, and we are able to influence which stable state we end up in".[4]: 28 

According to Fin Moorhouse, for most of human history, it was not clear how to positively influence the very long-run future.[27] However, two relatively recent developments may have changed this. Developments in technology, such as nuclear weapons, have, for the first time, given humanity the power to annihilate itself, which would impact the long-term future by preventing the existence and flourishing of future generations.[27] At the same time, progress made in the physical and social sciences has given humanity the ability to more accurately predict (at least some) of the long-term effects of the actions taken in the present.[27]

MacAskill also notes that our present time is highly unusual in that "we live in an era that involves an extraordinary amount of change"[4]: 26 —both relative to the past (where rates of economic and technological progress were very slow) and to the future (since current growth rates cannot continue for long before hitting physical limits).[4]: 26–28 

Theoretical considerations

Moral theory

Longtermism has been defended by appealing to various moral theories.[28] Utilitarianism may motivate longtermism given the importance it places on pursuing the greatest good for the greatest number, with future generations expected to be the vast majority of all people to ever exist.[29] Consequentialist moral theories—of which utilitarianism is just one example—may generally be sympathetic to longtermism since whatever the theory considers morally valuable, there is likely going to be much more of it in the future than in the present.[30]

However, other non-consequentialist moral frameworks may also inspire longtermism. For instance, Toby Ord considers the responsibility that the present generation has towards future generations as grounded in the hard work and sacrifices made by past generations.[6] He writes:[6]: 42 

Because the arrow of time makes it so much easier to help people who come after you than people who come before, the best way of understanding the partnership of the generations may be asymmetrical, with duties all flowing forwards in time—paying it forwards. On this view, our duties to future generations may thus be grounded in the work our ancestors did for us when we were future generations.

Evaluating effects on the future

In his book What We Owe the Future, William MacAskill discusses how individuals can shape the course of history. He introduces a three-part framework for thinking about effects on the future, which states that the long-term value of an outcome we may bring about depends on its significance, persistence, and contingency.[4]: 31–33  He explains that significance "is the average value added by bringing about a certain state of affairs", persistence means "how long that state of affairs lasts, once it has been brought about", and contingency "refers to the extent to which the state of affairs depends on an individual’s action".[4]: 32  Moreover, MacAskill acknowledges the pervasive uncertainty, both moral and empirical, that surrounds longtermism and offers four lessons to help guide attempts to improve the long-term future: taking robustly good actions, building up options, learning more, and avoiding causing harm.[4]

Population ethics

Illustrating the potential number of future human lives

Population ethics plays an important part in longtermist thinking. Many advocates of longtermism accept the total view of population ethics, on which bringing more happy people into existence is good, all other things being equal.[3] Accepting such a view makes the case for longtermism particularly strong because the fact that there could be huge numbers of future people means that improving their lives and, crucially, ensuring that those lives happen at all, has enormous value.[3][31]

Other sentient beings

See also: Speciesism and Animal welfare

Longtermism is often discussed in relation to the interests of future generations of humans. However, some proponents of longtermism also put high moral value on the interests of non-human beings.[32] From this perspective advocating for animal welfare may be an extremely important longtermist cause area because a moral norm of caring about the suffering of non-human life might persist for a very long time if it became widespread.[23]

Discount rate

Longtermism implies that we should use a relatively small social discount rate when considering the moral value of the far future. In the standard Ramsey model used in economics, the social discount rate is given by:

where is the elasticity of marginal utility of consumption, is the growth rate, and is a quantity combining the "catastrophe rate" (discounting for the risk that future benefits won't occur) and pure time preference (valuing future benefits intrinsically less than present ones). Ord argues that nonzero pure time preference is illegitimate, since future generations matter morally as much as the present generation. Furthermore, only applies to monetary benefits, not moral benefits, since it is based on diminishing marginal utility of consumption. Thus, the only factor that should affect the discount rate is the catastrophe rate, or the background level of existential risk.[6]: 241–245 

In contrast, Andreas Mogensen argues that a positive rate of pure time preference can be justified on the basis of kinship. That is, common-sense morality allows us to be partial to those more closely related to us, so "we can permissibly weight the welfare of each succeeding generation less than that of the generation preceding it."[33]: 9  This view is called temporalism and states that "temporal proximity (...) strengthens certain moral duties, including the duty to save".[34]



One objection to longtermism is that it relies on predictions of the effects of our actions over very long time horizons, which is difficult at best and impossible at worst.[35] In response to this challenge, researchers interested in longtermism have sought to identify "value lock in" events—events, such as human extinction, which we may influence in the near-term but that will have very long-lasting, predictable future effects.[36]

Deprioritization of immediate issues

Another concern is that longtermism may lead to deprioritizing more immediate issues. For example, some critics have argued that considering humanity's future in terms of the next 10,000 or 10 million years might lead to downplaying the nearer-term effects of climate change.[37] They also worry that by specifying the end-goal of human development as "technological maturity," or the subjugation of nature and maximization of economic productivity, the longtermist worldview could worsen the environmental crisis and justify atrocities in the name of attaining "astronomical" amounts of future value. Anthropologist Vincent Ialenti has argued that avoiding this will require societies to adopt a "more textured, multifaceted, multidimensional longtermism that defies insular information silos and disciplinary echo chambers."[38]

Advocates of longtermism reply that the kinds of actions that are good for the long-term future are often also good for the present.[3] An example of this is pandemic preparedness. Preparing for the worst case pandemics—those which could threaten the survival of humanity—may also help to improve public health in the present. For example, funding research and innovation in antivirals, vaccines, and personal protective equipment, as well as lobbying governments to prepare for pandemics, may help prevent smaller scale health threats for people today.[39]

Reliance on small probabilities of large payoffs

A further objection to longtermism is that it relies on accepting low probability bets of extremely big payoffs rather than more certain bets of lower payoffs (provided that the expected value is higher).[40][41] From a longtermist perspective, it seems that if the probability of some existential risk is very low, and the value of the future is very high, then working to reduce the risk, even by tiny amounts, has extremely high expected value. An illustration of this problem is Pascal’s mugging, which involves the exploitation of an expected value maximizer via their willingness to accept such low probability bets of large payoffs.[42]

Advocates of longtermism have adopted a variety of responses to this concern. Some argue that, while unintuitive, it is ethically correct to favor infinitesimal probabilities of arbitrarily high-impact outcomes over moderate probabilities with moderately impactful outcomes.[40] Others argue that longtermism need not rely on tiny probabilities as the probabilities of existential risks are within the normal range of risks that people seek to mitigate against— for example, wearing a seatbelt in case of a car crash.[41]

See also


  1. ^ a b Moorhouse, Fin (2021-01-27). "Introduction to Longtermism". Effective Altruism. Retrieved 2023-06-02.
  2. ^ Samuel, Sigal (2021-11-03). "Would you donate to a charity that won't pay out for centuries?". Vox. Retrieved 2021-11-13.
  3. ^ a b c d Greaves, Hilary; MacAskill, William (2021). "The case for strong longtermism". Global Priorities Institute Working Paper. 5. Archived from the original on 9 July 2022.
  4. ^ a b c d e f g h i MacAskill, William (2022). What We Owe the Future. New York: Basic Books. ISBN 978-1-5416-1862-6.
  5. ^ a b MacAskill, William (2019-07-25). "Longtermism". Effective Altruism Forum.
  6. ^ a b c d e f g h i j Ord, Toby (2020). The Precipice: Existential Risk and the Future of Humanity. London: Bloomsbury Publishing. ISBN 978-1-5266-0021-9. OCLC 1143365836.
  7. ^ Rowe, Thomas; Beard, Simon (2018). "Probabilities, methodologies and the evidence base in existential risk assessments" (PDF). Working Paper, Centre for the Study of Existential Risk. Archived (PDF) from the original on 27 August 2018. Retrieved 26 August 2018.
  8. ^ Constitution of the Iroquois Nations, 1910.
  9. ^ Lyons, Oren (October 2004). "The Ice is Melting". Center for New Economics. Archived from the original on 11 May 2022.
  10. ^ Samuel, Sigal (2021-07-02). "What we owe to future generations". Vox. Retrieved 2021-11-27.
  11. ^ "Our Mission". Retrieved 2021-11-28.
  12. ^ "About Us: Future of Humanity Institute". The Future of Humanity Institute. Retrieved 2021-11-28.
  13. ^ "About us: what do we do, and how can we help?". 80,000 Hours. Retrieved 2021-11-28.
  14. ^ "Global Catastrophic Risks". Open Philanthropy. 2016-03-02. Retrieved 2021-11-28.
  15. ^ "Team". Future of Life Institute. Retrieved 2021-11-28.
  16. ^ "About Us – Forethought Foundation". Forethought Foundation for Global Priorities Research. 2022.
  17. ^ Matthews, Dylan (2022-08-08). "How effective altruism went from a niche movement to a billion-dollar force". Vox. Retrieved 2022-08-27.
  18. ^ a b c Beckstead, Nick (2013). "Chapter 1.1.2: How could we affect the far future?". On The Overwhelming Importance of Shaping the Far Future. New Brunswick Rutgers, The State University of New Jersey.
  19. ^ Bostrom, Nick (2013). "Existential Risk Prevention as Global Priority". Global Policy. 4 (1): 15–31. doi:10.1111/1758-5899.12002.
  20. ^ Moorhouse, Fin (2021). "Longtermism - Frequently Asked Questions: Is longtermism asking that we make enormous sacrifices for the future? Isn't that unreasonably demanding?". Archived from the original on 14 July 2022.
  21. ^ Cowen, Tyler (2018). Stubborn Attachments: A Vision for a Society of Free, Prosperous, and Responsible Individuals. Stripe Press. ISBN 978-1732265134.
  22. ^ John, Tyler M.; MacAskill, William (2021). "Longtermist institutional reform". In Cargill, Natalie; John, Tyler M. (eds.). The Long View (PDF). UK: FIRST Strategic Insight. ISBN 978-0-9957281-8-9.
  23. ^ a b Reese, Jacy (20 February 2018). "Why I prioritize moral circle expansion over reducing extinction risk through artificial intelligence alignment". Effective Altruism Forum.
  24. ^ a b MacAskill, William (23 May 2022). "Will MacAskill on balancing frugality with ambition, whether you need longtermism, and mental health under pressure". 80,000 Hours.
  25. ^ a b Leslie Brown, Christopher (2006). Moral Capital: Foundations of British Abolitionism. UNC Press. ISBN 978-0-8078-5698-7.
  26. ^ Parfit, Derek (2011). On What Matters, Volume 2. Oxford: Oxford University Press. p. 611.
  27. ^ a b c Moorhouse, Fin (2021). "Longtermism - Frequently Asked Questions: Isn't much of longtermism obvious? Why are people only just realising all this?". Archived from the original on 14 July 2022.
  28. ^ Crary, Alice (2023). "The Toxic Ideology of Longtermism". Radical Philosophy 214. Retrieved 2023-04-11.
  29. ^ MacAskill, William; Meissner, Darius (2022). "Utilitarianism and Practical Ethics – Longtermism: Expanding the Moral Circle Across Time". An Introduction to Utilitarianism. Archived from the original on 16 June 2022.
  30. ^ Todd, Benjamin (2017). "Longtermism: the moral significance of future generations". 80,000 Hours.
  31. ^ Malde, Jack (9 March 2021). "Possible misconceptions about (strong) longtermism: "Longtermists must be total utilitarians"". Effective Altruism Forum.
  32. ^ Baumann, Tobias (2020). "Longtermism and animal advocacy". Center for Reducing Suffering. Archived from the original on 14 July 2022.
  33. ^ Mogensen, Andreas (October 2019). "'The only ethical argument for positive 𝛿'?" (PDF). Global Priorities Institute. Retrieved 30 December 2021.
  34. ^ Lloyd, Harry (2021). "Time discounting, consistency and special obligations: a defence of Robust Temporalism". Global Priorities Institute Working Paper. 11.
  35. ^ Tarsney, Christian (2019). "The epistemic challenge to longtermism". GPI Working Paper (10–2019).
  36. ^ MacAskill, William (2021). McMahan, Jeff; Campbell, Tim; James, Goodrich (eds.). "Are we living at the hinge of history?". Ethics and Existence: The Legacy of Derek Parfit. Oxford University Press.
  37. ^ Torres, Phil (2021-10-19). Dresser, Sam (ed.). "Why longtermism is the world's most dangerous secular credo". Aeon. Retrieved 2021-11-02.
  38. ^ "Deep Time Reckoning". MIT Press. Retrieved 2022-08-14.
  39. ^ Lewis, Gregory (2020). "Risks of catastrophic pandemics". 80,000 Hours.
  40. ^ a b Wilkinson, Hayden (2020). "In defence of fanaticism". Global Priorities Institute Working Paper. 4.
  41. ^ a b Kokotajlo, Daniel (2018). "Tiny Probabilities of Vast Utilities: Concluding Arguments". Effective Altruism Forum.
  42. ^ Bostrom, Nick (2009). "Pascal's mugging" (PDF). Analysis. 69 (3): 443–445. doi:10.1093/analys/anp062.

Further reading