Tim Harford, in an otherwise worthwhile article about the economic realities of charity, seriously drops the logical ball when he writes:
"Even the way we choose to dole out cash betrays our true motives. Someone with $100 to give away and a world full of worthy causes should choose the worthiest and write the check. We don't. Instead, we give $5 for a LiveStrong bracelet, pledge $25 to Save the Children, another $25 to AIDS research, and so on. But $25 is not going to find a cure for AIDS. Either it's the best cause and deserves the entire $100, or it's not and some other cause does. The scattershot approach simply proves that we're more interested in feeling good than doing good.
Many people are unconvinced by this argument...because they are used to diversifying their financial investments (a bit of Google stock and a bit of Exxon, too) and varying their choices (vanilla ice cream AND bananas). But those instincts are selfish: They are not intended to benefit both Google and Exxon, nor both the ice-cream company and the banana growers. With charity, the logic is different, and a truly selfless donor would bite the bullet and put his entire donation behind one cause. That we find that so hard to imagine is just one more indication of how hard it is for us to think ourselves into a truly selfless view of the world.
How many logical flaws can you find in this reasoning? I count at least three:
1. The argument assumes that there is such a thing as a "best choice" when it comes to charity, and of course there isn't. The value of the work done by charitable orgnizations is incommensurate. How do you compare the value of an organization that works to save the oceans with one that works to save the rain forests or find a cure for cancer?
2. Even assuming that there is such a thing as a single best choice, the argument assumes that you know what the best choice is with absolute certainty. If you knew which stock would perform best there would be no need for diversification. Likewise, because you can't know which charity is "best" diversification makes sense to hedge against that uncertainty.
3. Even if you assume that there is a best choice and you know what it is, the argument assumes that the incremental value of money is constant. In other words, the argument assumes that the giving of money does not change the relative ranking of organizations. But of course that's not true because of the law of diminshing returns. At some point the relative effectiveness (and hence value) of additional resources begins to decline.
There are probably others. It's a shame that the editorial staff at Slate, which is usually pretty good about filtering out complete bogosity, dropped the ball so hard in this case.