William MacAskill is an Associate Professor of Philosophy at Oxford University. He has published in philosophy journals such as Mind, Ethics, and the Journal of Philosophy, and has authored the bestselling book Doing Good Better (Avery, 2015). He cofounded the international non-profits Centre for Effective Altruism; 80,000 Hours; and Giving What We Can. Krister Bykvist is a Professor in Practical Philosophy at Stockholm University and a Research Fellow at the Institute for Future Studies, Stockholm. His articles have appeared in Economics and Philosophy, Philosophical Studies, and the Australasian Journal of Philosophy. His research concerns questions about our responsibility for future generations, the foundations of consequentialism, evaluative uncertainty, and the relationship between preferences, value, and welfare. He is currently leading the Valuing Future Lives project. Toby Ord is a Research Fellow at the Future of Humanity Institute, University of Oxford. His research concerns some of the key questions facing humanity, identifying what the most important issues of our time are and how we can best address them. His research previously focused on the ethics of global health and global poverty, and he is the creator of Giving What We Can, an international society focusing on pledging to the most effective charities. He is also the co-founder of the Effective Altruism movement.