by Grace Boey
A runaway train trolley is racing towards five men who are tied to the track. By pulling a lever, you could divert the train's path to an alternative track, which has only one man on it …
If you're gearing up to respond with what you'd do and why, don't bother. It doesn't matter whether you'd pull the lever: it's too late. The five were run over almost fifty years ago, because philosophers couldn't decide what to do. They have been – pun most certainly intended – debated to death.
Formulated by the late Philippa Foot in 1967, the famous “trolley problem” has since been endlessly picked apart and argued over by moral philosophers. It's even been reformulated – apart from “classic”, the trolley problem also comes in “fat man”, “loop”, “transplant” and “hammock” varieties. Yet, in spite of all the fascinating analysis, there still isn't any good consensus on what the right thing is to do. And, not only do philosophers disagree over what to do, a significant number of them just aren't sure. In a 2009 survey of mostly professional philosophers, 34.8% of the respondents indicated some degree of uncertainty over the right answer [1].
Philosopher or not, if you're in the habit of being intellectually honest, then there's a good chance you aren't completely certain about all your moral beliefs. Looking to the ethics textbooks doesn't help – you'd be lucky not to come away from that with more doubts than before. If the philosophical field of ethics is supposed to resolve our moral dilemmas, then on some level it has obviously failed. Debates over moral issues like abortion, animal rights and euthanasia rage on, between opposing parties and also within the minds of individuals. These uncertainties won't go away any time soon. Once we recognize this, then the following question naturally arises: what's the best way to act under moral uncertainty?
Ethicists, strangely, have mostly overlooked this question. But in relatively recent years, a small group of philosophers have begun rigorous attempts at addressing the problem. In particular, attempts are being made to adapt probability and expected utility theory to decision-making under moral uncertainty.