So what is the right amount to give away? 10%? 50%? 95%? If one stops at 10%, does that mean that he cares, but just not very much?
Sam, there was an article about exactly this topic in the New York Times magazine on December 17, 2006, by Peter Singer of Princeton University. It was entitled "What Should a Billionaire Give -- And What Should You?" It's a fascinating article, and I recommend it highly; reading it had a huge effect on me. It's available here:http://www.utilitarian.net/singer/by/20061217.htm
Singer, who is a bioethicist, took a very logical and data-substantiated look at the question of how much one "should" ethically give away in order to help reduce world poverty (he himself gives away 25% of his income every year, mostly to Oxfam, although he doesn't mention that in this article).
Here are his recommendations:
If you're one of the 14,400 US taxpayers who earn more than $5 million a year, Singer recommends giving away 33% of your income each year.
If you're one of the 129,600 US taxpayers who earn more than $1.1 million (excluding the group above...this rule applies for all the categories below), you should give away 25 percent of your income.
If you're one of the 575,900 taxpayers who earn more than $407,000 a year, give away 20 percent of your income.
If you're one of the 719,900 taxpayers who earn more than $276,000 a year, give away 15 percent of your income.
If you're one of the 13 million taxpayers who earn more than $92,000 a year, give away 10 percent of your income.
Here's Singer's home page at Princeton, in case you want to read more of his writings:http://www.princeton.edu/~psinger/index.html