In 2017, the Scottish philosopher William MacAskill coined the name "longtermism" to describe the idea "that positively affecting the long-run future is a key moral priority of our time." The label took off among like-minded philosophers and members of the "effective altruism" movement, which sets out to use evidence and reason to determine how individuals can best help the world.

This year, the notion has leapt from philosophical discussions to headlines. In August, MacAskill published a book on his ideas, accompanied by a barrage of media coverage and endorsements from the likes of Elon Musk. November saw more media attention as a company set up by Sam Bankman-Fried, a prominent financial backer of the movement, collapsed in spectacular fashion.

Critics say longtermism relies on making impossible predictions about the future, gets caught up in speculation about robot apocalypses and asteroid strikes, depends on wrongheaded moral views, and ultimately fails to give present needs the attention they deserve.

But it would be a mistake to simply dismiss longtermism. It raises thorny philosophical problems—and even if we disagree with some of the answers, we can't ignore the questions.

To read more, click here.