The thought experiment is simple enough to be taught to undergraduates and troubling enough to haunt adults. You are walking past a shallow pond when you see a child face-down in the water. You can wade in and pull him out, but doing so will ruin your shoes and muddy your clothes. Who but a monster would not agree that you should wade in and save the child, whatever the cost to your shoes? The Australian philosopher Peter Singer held that the basic “intuition” most of us have about this