Launching An Introductory Online Textbook on Utilitarianism

We are excited to announce the launch of, an introductory online textbook on utilitarianism, co-created by William MacAskill, James Aung and me over the past year.


The website aims to provide a concise, accessible and engaging introduction to modern utilitarianism, functioning as an online textbook targeted at the undergraduate level . We hope that over time this will become the main educational resource for students and anyone else who wants to learn about utilitarianism online. The content of the website aims to be understandable to a broad audience, avoiding philosophical jargon where possible and providing definitions where necessary.

Please note that the website is still in beta. We plan to produce an improved and more comprehensive version of this website by September 2020. We would love to hear your feedback and suggestions on what we could change about the website or add to it.

The website currently has articles on the following topics and we aim to add further content in the future:

  1. Introduction to Utilitarianism

  2. Principles and Types of Utilitarianism

  3. Utilitarianism and Practical Ethics

  4. Objections to Utilitarianism and Responses

  5. Acting on Utilitarianism

  6. Utilitarian Thinkers

  7. Resources and Further Reading

We are particularly grateful for the help of the following people with reviewing, writing, editing or otherwise supporting the creation of Lucy Hampton, Stefan Schubert, Pablo Stafforini, Laura Pomarius, John Halstead, Tom Adamczewski, Jonas Vollmer, Aron Vallinder, Ben Pace, Alex Holness-Tofts, Huw Thomas, Aidan Goth, Chi Nguyen, Eli Nathan, Nadia Mir-Montazeri and Ivy Mazzola.

The following is a partial reproduction of the Introduction to Utilitarianism article from Please note that it does not include the footnotes, further resources, and the sections on Arguments in Favor of Utilitarianism and Objections to Utilitarianism. If you are interested in the full version of the article, please read it on the website.

Introduction to Utilitarianism

The utilitarian doctrine is, that happiness is desirable, and the only thing desirable, as an end; all other things being only desirable as means to that end.”
- John Stuart Mill

Utilitarianism was developed to answer the question of which actions are right and wrong, and why. Its core idea is that we ought to act to improve the wellbeing of everyone by as much as possible. Compared to other ethical theories, it is unusually demanding and may require us to make substantial changes to how we lead our lives. Perhaps more so than any other ethical theory, it has caused a fierce philosophical debate between its proponents and critics.

Why Do We Need Moral Theories?

When we make moral judgments in everyday life, we often rely on our intuition. If you ask yourself whether or not it is wrong to eat meat, or to lie to a friend, or to buy sweatshop goods, you probably have a strong gut moral view on the topic. But there are problems with relying merely on our moral intuition.

Historically, people held beliefs we now consider morally horrific. In Western societies, it was once firmly believed to be intuitively obvious that people of color and women have fewer rights than white men; that homosexuality is wrong; and that it was permissible to own slaves. We now see these moral intuitions as badly misguided. This historical track record gives us reason to be concerned that we, in the modern era, may also be unknowingly guilty of serious, large-scale wrongdoing. It would be a very lucky coincidence if the present generation were the first generation whose intuitions were perfectly morally correct.

Also, people have conflicting moral intuitions about what things are right and wrong. So, we need a way to resolve these disagreements. The project of moral philosophy is to reflect on our competing moral intuitions and develop a theory that will tell us which actions are right or wrong, and why. This will then allow us to identify which moral judgments of today are misguided, enabling us to make moral progress and act more ethically.

One of the most prominent and influential attempts to create such a theory is utilitarianism. Utilitarianism was developed by the philosophers Jeremy Bentham and John Stuart Mill, who drew on ideas going back to the ancient Greeks. Their utilitarian views have been widely discussed since and have had a significant influence in economics and public policy.

Explaining What Utilitarianism Is

The core idea of utilitarianism is that we ought to act to improve the wellbeing of everyone by as much as possible.

A more precise definition of utilitarianism is as follows:

Utilitarianism is the family of ethical theories on which the rightness of actions (or rules, policies, etc.) depends on, and only on, the sum total of wellbeing they produce.

Sometimes philosophers talk about “welfare” or “utility” rather than “wellbeing”, but these words are typically used to mean the same thing. Utilitarianism is most commonly applied to evaluate the rightness of actions, but the theory can also evaluate other things, like rules, policies, motives, virtues, and social institutions. It is perhaps unfortunate that the clinical-sounding term “utilitarianism” caught on as a name, especially since in common speech the word “utilitarian” is easily confused with joyless functionality or even outright selfishness.

All ethical theories belonging to the utilitarian family share four defining characteristics: (i) consequentialism, (ii) welfarism, (iii) impartiality, and (iv) additive aggregationism.

  • Consequentialism is the view that the moral rightness of actions (or rules, policies, etc.) depends on, and only on, the value of their consequences.

  • Welfarism is the view that only the welfare (also called wellbeing) of individuals determines how good a particular state of the world is.

  • Impartiality is the view that the identity of individuals is irrelevant to the value of an outcome.

  • Additive Aggregationism is the view that the value of the world is given by the sum of the values of its parts, where these parts are some kind of local phenomena such as experiences, lives, or societies.

The major rivals to utilitarianism are philosophies that deny one or more of the above four core principles. For example, they might believe that actions can be inherently right or wrong regardless of their consequences, or that some outcomes are good even if they do not increase the welfare of any individual, or that morality allows us to be partial towards our friends and families.

We cover the core principles of utilitarianism and its variants in greater depth in a separate article.

Classical Utilitarianism

The early utilitarians—Jeremy Bentham, John Stuart Mill, and Henry Sidgwick—were classical utilitarians. Classical utilitarianism is distinctive from other utilitarian theories because it accepts these two additional principles: First, it accepts hedonism as a theory of welfare. Hedonism is the view that wellbeing consists of positive and negative conscious experiences. For readability, we will call positive conscious experiences happiness and negative conscious experiences suffering. Second, classical utilitarianism accepts totalism as a theory of population ethics. Totalism is the view that one outcome is better than another if and only if it contains a greater sum total of wellbeing, where wellbeing can be increased either by making people better off or increasing the number of people with good lives.

Classical utilitarianism can be defined as follows:

Classical utilitarianism is the ethical theory on which the rightness of actions (or rules, policies, etc.) depends on, and only on, the sum total of happiness over suffering they produce.

Utilitarianism and Practical Ethics

Utilitarianism is a demanding ethical theory that may require us to substantially change how we act. Utilitarianism says that we should make helping others a very significant part of our lives. In helping others, we should try to use our resources to do the most good, impartially considered, that we can.

According to utilitarianism, we should extend our moral concern to all sentient beings, meaning every individual capable of experiencing positive or negative conscious states. On this basis, a priority for utilitarians may be to help society to continue to widen its moral circle of concern. For instance, we may want to persuade people they should help not just those in their own country, but also on the other side of the world; not just those of their own species but all sentient creatures; and not just people currently alive but any people whose lives they can affect.

Despite having a radically different approach to ethics than commonsense morality, utilitarianism generally endorses commonsense prohibitions. For practical purposes, the best course of action for a utilitarian is to try to do as much good as possible whilst still acting in accordance with commonsense moral virtues—like integrity, trustworthiness, law-abidingness, and fairness.

We discuss the implications of utilitarianism for practical ethics in a separate article.

Acting on Utilitarianism

There are many problems in the world today, some of which are extremely large in scale. Unfortunately, our resources are scarce, so as individuals and even as a global society we cannot solve all the world’s problems at once. This means we must decide how to prioritize the resources we have. Not all ways of helping others are equally effective. By the lights of utilitarianism, we should choose carefully which moral problems to work on and by what means, based on where we can do the most good. This involves taking seriously the question of how we can best use our time and money to help others. Once again, utilitarianism urges us to consider the wellbeing of all individuals regardless of what species they belong to, what country they live in, and at what point in time they exist. With this in mind, a few moral problems appear especially pressing:

  • Global Health and Development. Those in affluent countries are typically one hundred times richer than the poorest seven hundred million people in the world. Also, we can radically improve the lives of the extreme poor, such as by providing basic medical care, at very little cost.

  • Factory Farming. Tens of billions of non-human animals are kept in horrific conditions in factory farms, undergoing immense unnecessary suffering. We could radically decrease this suffering at very little cost to society.

  • Existential Risks. There will be vast numbers of people in the future, and their lives could be very good. Yet technological progress brings risks, such as from climate change, nuclear war, synthetic biology and artificial intelligence, that could endanger humanity’s future. But if we can successfully navigate these risks, we can ensure a flourishing world for trillions of people yet to come.

There are three key means of helping those affected by the above moral concerns: donating money to effective charities, working in an impactful career, and convincing other people to do the same. For example, donations to the most effective global health charities are expected to save a human life for as little as $2,300; this money may go even further when donated to address factory farming or existential risks. Choosing which career to pursue may be even more important again, since some careers allow us to do far more good than others.

In a separate article, we discuss what utilitarianism means for how we should act.

[The full version of this article includes two additional sections here, one on Arguments in Favor of Utilitarianism, the other on Objections to Utilitarianism.]


What matters most for utilitarianism is bringing about the best consequences for the world. This involves improving the wellbeing of all individuals, regardless of their gender, race, species, and their geographical or temporal location. Against this background, three key concerns for utilitarianism are helping the global poor, improving farmed animal welfare, and ensuring that the future goes well over the long term. Since utilitarianism is unusually demanding, it may require us to make benefiting others the main focus of our lives.

All utilitarian theories share the four core principles of consequentialism, welfarism, impartiality, and additive aggregationism. The original and most influential version of utilitarianism is classical utilitarianism, which encompasses two further characteristics: hedonism and totalism. Hedonism is the view that wellbeing consists entirely of conscious experiences, such as happiness or suffering. Totalism is the view that one outcome is better than another if and only if it contains a greater sum total of wellbeing.