My understanding is that Peter Singer argues that because you would ruin your shoes to jump into a creek to save a drowning child, you should incur an equivalent cost to save the life of a child in the third world.
BTW that is no longer possible (if it ever even was) unless you're wearing pretty expensive shoes indeed.
On the other hand, a pair of dress shoes and a suit might still be more expensive, and might get ruined when you save somebody from a pool of mud.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
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