Stephen Dubner asked a few luminaries to answer this question:
You are walking down the street in New York City with $10 of disposable income in your pocket. You come to a corner with a hot dog vendor on one side and a beggar on the other. The beggar looks like he’s been drinking; the hot dog vendor looks like an upstanding citizen. How, if at all, do you distribute the $10 in your pocket, and why?
Here are their answers. I’m not a luminary but I’ll exercise my right to answer.
The first question is whether I’m hungry. If I am, I probably buy myself a hot dog, and then reluctantly allow the beggar to relieve me of the remainder. If I’m not hungry, I probably wind up giving ten bucks to the beggar, on the grounds that he needs the money more than I do. Refusing to give money to a beggar when asked directly makes me feel guilty.
If my wife is with me, forking over the full $10 is guaranteed. If I feel like the beggar is trying to run a scam on me, he probably still gets the $10 (or the change from the hot dog) but I feel irritated about it afterward.