In discussion about my posts on organic food it was pointed out that my argument depends on the idea that one should only give to one charity. Because I believe that oxfam would do more good with my money than a make food organic charity, I claim that I (and others) should give money only to oxfam and not the MFO-charity.

The "one charity" argument makes a lot of sense to me: if my best estimate of how much good oxfam will do with my money is substantially greater than the amount of good some other charity will do, why should I give to that other charity when I could be more effective by giving to oxfam? More detailed arguments on this point are also out there:

• Slate: Giving Your All
• Thinking Beyond Competition: The One Charity Argument and the End of Poverty
• GiveWell: Denying the Choice

Update 2013-02-26: I've expanded on this some.