Philosophy and the Law | The Large Man and the Shallow Pond: two thought experiments in moral philosophy

Thursday 23 January 2025

Dr David Edmonds will be discussing two thought experiments in moral philosophy, as outlined below, designed to help people think analytically about ethical affairs.

The Shallow Pond

Imagine this.

You’re walking across a park, and you pass a shallow pond.  There’s a noise, and when you look closer, you see that in the pond there’s a toddler thrashing around.  She’s obviously in danger of drowning.  You look around for her parents or carer, but there’s nobody there.  You’re the only person who can save her, but to do so you must act immediately.

There’s only one problem.  As you approach the pond you remember that you’re wearing your most expensive shoes.  They cost £150 and wading into the water will ruin them.  What’s more, it might make you late for your morning meeting.  So, should you let the child drown?

This one thought experiment, conjured up by Peter Singer in 1971, has spawned an enormous literature and been hugely influential in changing attitudes to poverty.  Letting people in the developing world die, when they could be so easily helped, is no different from failing to save the drowning child – so the argument goes.

Effective Altruism is just one direct consequence of this thought experiment – a global movement which encourages us to give more, and to give more effectively – in other words, to do as much good as we can.  But is the Shallow Pond really an analogy with the real world?

The Large Man

In 1967, a famous Oxford philosopher wrote an article about abortion in which she justified the procedure with a striking fictitious example.  It involved a train that was out of control and was heading towards some unsuspecting innocents.  The author, Philippa Foot, wanted to work out what counted as acceptable killing.  She could never have predicted that her flight of fancy would create a mini-industry.  For the past four decades, fantasy cases, involving out-of-control trains, have been used by moral philosophers to debate right and wrong.  There are now so many of these scenarios that the study of them has even been given a name – trolley-ology.  One case involves pushing a large man over a footbridge.  Our responses to these surreal dilemmas carry implications for numerous contested moral areas.