“In all ages of speculation, one of the strongest obstacles to the reception of the doctrine that Utility or Happiness is the criterion of right and wrong, has been drawn from the idea of Justice.” This is from John Stuart Mill’s Utilitarianism, in 1861, perhaps the most renowned exposition of the ethical theory that stands behind the contemporary movement that calls itself “effective altruism,” known widely as EA. Mill’s point is powerful and repercussive. I will return to the challenge that justice poses to utilitarianism presently. But first, what is effective altruism? The two hubs of the movement are Oxford and Princeton. Oxford is home to the Centre for Effective Altruism, founded in 2012 by Toby Ord and William MacAskill, and Princeton is where Peter Singer, who provides the philosophical inspiration for EA, has taught for many years. Singer is EA’s most direct philosophical source, but it has deeper if less direct sources in the thought of the Victorian moral philosopher Henry Sidgwick and the contemporary moral philosopher Derek Parfit, who died a few years ago. Sidgwick gave utilitarianism a rigorous formulation as well as a philosophically sophisticated grounding. He showed that utilitarianism need not depend, as it did in Bentham and Mill, on an implausible naturalism that seeks to reduce ethics to an empirical science. Parfit was strongly influenced by Sidgwick, as indeed is Singer. Parfit’s Reasons and Persons was important for several reasons. When it was published in 1984, moral and political philosophy was under the influence of John Rawls, whose Theory of Justice had appeared in 1971 in the wake of the civil rights and other social justice movements. Rawls’ notion of “justice as fairness” provided the first systematic alternative to utilitarianism and a seemingly persuasive critique of it. Utilitarianism, Rawls argued, did not take sufficiently seriously the “separateness of persons,” since it allowed tradeoffs between benefits and harms that we are content with within an individual life — deferring gratification for future benefit, for example — and applied them, unjustly, across an aggregate of lives. It allowed harms to some to be weighed impersonally against benefits to others, and so treated individuals as though they were simply parts of a social whole, analogously to the way we regard individual moments of our lives. But Parfit argued, on sophisticated metaphysical grounds, that personal identity is not the simple all-or-nothing thing that Rawls’ objection presupposed. And he argued persuasively that utilitarianism can be defended against a number of other challenges that its critics had raised from the perspective of justice. Parfit also showed how taking utilitarianism seriously leads to a number of important questions concerning our relation to the future in the long term. Singer’s main contributions have been in what is called, somewhat deprecatingly, “applied ethics.” He has influentially argued on broadly utilitarian grounds that we have significant obligations to address global poverty and to avoid the inhumane treatment of nonhuman animals. Singer’s Animal Liberation, published in 1975, has spawned a massive increase in vegetarianism and attention to animal welfare. And his essay ““Famine, Affluence, and Morality,” which appeared in 1972, may be the most widely assigned article in college ethics courses. Singer is also the author of The Most Good You Can Do: How Effective Altruism is Changing Ideas About Living Ethically. Ord and MacAskill are from a younger generation. Their role has been to put Singer’s conclusions into practice by founding and running the Centre for Effective Altruism and the Global Priorities Institute, also at Oxford, and by attracting a large number of “the best and the brightest” to EA. MacAskill is the author of Doing Good Better: How Effective Altruism Can Help You Help Others, Do Work That Matters, and Make Smarter Choices About Giving Back. And Ord plays a lead role in the organization Giving What We Can, whose members pledge to donate at least ten percent of their income to “effective charities.” He and MacAskill are also central figures in the development of “long-termism,” a branch of effective altruism which argues that we should focus more on benefits and harms in what Parfit called the “farther future.” The moral and philosophical idea that drives much of “effective altruism” comes from a famous example — known as “Singer’s pond case” — that Singer discusses in his essay. Imagine that you are walking past a shallow pond in which a child is drowning and that you can save the child at the cost of getting your pants wet. It seems uncontroversial to hold that it would be wrong not to save the child to spare your pants. Singer argues that the world’s poor are in a similar position. They are dying from famine, disease, and other causes, in some cases literally drowning from the effects of climate change. Analogously, we in the developed world can address many of these threats to human (and other animal) life and well-being at relatively little cost. It seems to follow, therefore, that we are obligated to do so and that it would be wrong for us not to do so. Singer’s larger teaching is that we are obligated on roughly utilitarian grounds to absorb as much cost as would be necessary to make those whom we can benefit no worse off than we are. Yet we do not have to draw such a radical conclusion to be convinced by Singer’s analogy that we have very significant obligations to help address global poverty. And it may well be that Giving What We Can’s minimum standard of ten percent of income is morally appropriate. Let us begin by examining more closely the relationship between effective altruism and utilitarianism, and what together they assert. MacAskill offers the following definition: Effective altruism is about asking, “How can I make the biggest difference I can?” And using evidence and careful reasoning to try to find an answer. It takes a scientific approach to doing good. Just as science consists of the honest and impartial attempt to work out what’s true, and a commitment