Deere of GWWC says the movement has been in existence for less than a decade and is just getting started. But he also believes that many people - particularly in the charity sector - might be resistant to effective altruism because they don't want to accept they might not have been directing their energy or donations into the most effective areas. "It's difficult for people to think that this thing they've given so much of themselves and their time to might not actually have been the best use of that time," he says.

"Most people give to charity because they really want to make the world a better place," he says. "To do that, you need to start making some of these choices. Most people who think about these ideas for any length of time are at least broadly convinced."