Saving the many or the few:the moral relevance of numbers

To your left, three strangers are drowning. To your right, one other stranger is drowning. You can effortlessly save the three by throwing a lifebuoy to your left. Alternatively, you can save the one by throwing the lifebuoy to your right. You cannot save all four. What should you do? It’s wrong to do nothing, but is it wrong to save just the one stranger? Are you morally required to save the three? Many claim that, when those you can help are innocent strangers with similar interests at stake, you’re required to save the greater number. Is this claim justified? This essay reviews some doubts