One wouldn't put all of one's money into one stock in the market because we have decreasing marginal utility towards money. If we didn't and all we wanted was the highest expected value (which is how we should optimize for charity), then we would put our money into the stock that is likeliest to make us the most money.
In other words, I don't want to have a minimum number of lives saved - I want to maximize the number of lives I save.
Perhaps I didn't express my point clearly enough. In fact, I'm certain of it. But I more trying to express that there is some element of risk in a charity. Perhaps there is a probability is corrupt, etc. and isn't as efficient as it's rated as. A better example is likely this:
Assuming it will succeed, the SIAI is pretty unarguably the most important charity in existence. But that's a huge assumption, and it makes some sense to hedge against that bet and distribute money to other charities as well.
When I was a graduate student at the University of Notre Dame, I received a monthly living stipend of roughly $1,600. I decided to commit to giving ~10% of it to charity, and I had read in Peter Singer's book The Life You Can Save that one of the most efficient charities out there was Population Services International (PSI). Singer reported that GiveWell, a leading charity rating organization, had estimated that PSI's efforts saved lives at a cost of $650-$1000 each (pp. 88-89). So, I set up a recurring monthly donation of $160 to PSI, and kept it up for 15 months, for a total donation of $2,400.
I've been meaning to post the above information publicly for awhile, but was pushed over the edge by reading one of Eliezer's posts from a couple years back, Why Our Kind Can't Cooperate:
Since Eliezer's post is about rationalists, he stresses the issue of what arguments people voice. However, we know that just telling other people that you've given to charity makes them more likely to give. This is a point that Singer himself has emphasized.
I propose a thread for people to publicize their charitable donations. In light of the above, I'm especially interested to hear from people who've donated to the Singularity Institute for Artificial Intelligence. Once I acquire a regular source of income again in March, I intend to continue to primarily direct my charitable giving towards PSI, but maybe someone in this thread will persuade me to start giving to the Singularity Institute.