# Archive for June, 2010

## The Rational for Giving

Posted by Patrick on June 15, 2010

Usually, when we’re asked to donate money for a good cause, we end up feeling guilty some way or another. Maybe it’s because we know we don’t give enough, but for me, I know it’s because I chose to ignore all the bad things I feel helpless towards.  A few days ago, I listened to an excellent interview [1] on KQCD of Peter Signer [2], a philosophy professor at Princeton University who specializes in applied ethics.  In contrast to what I was expecting, his interview made me feel hopeful!  He gave one of the clearest, most level headed and rational argument of why we should all donate a small portion of our yearly income to help the poorest of the planet.  But not only that, he put a system in place so that we know we’re not alone in doing it and that our group effort is making a difference.

Basically, those of us making less than 120000 CAN\$ should give about 1% of our income.  If we earn more, that percentage should go up.  There’s a calculator on The Life You Can Save website [3] to help us figure out our contributions.  Of course, since I’m a little bit of a math geek, I went a head and plotted a few points (actually, quite a few) to extract the formulae that dictate the amount of donation when the income is less than 10 million dollars per year (you never know!)  Here, $y$ is the donation amount and $x$ is the yearly income (in thousands of Canadian dollars).

$y = 0.01 x \quad ; 0 \leq x < 12k$

$y = 0.05 x \quad ; 12 \leq x < 190k$

$y = 0.1 x-0.91 \quad ; 190k \leq x < 480k$

$y = 0.1 5 x -3.265 \quad ; 480k \leq x < 740k$

$y = 0.2 x -6.95 \quad ; 740k\leq x < 10M$

To get a sense of what this means, I plotted the amount of money that would be left after making the donation (in blue) compared to the income (doted black line) with the vertical red lines representing the amount of money donated.

You can also see the percentage that we should donate as a function of our income.

Here’s a very quick video summarizing Signer’s argument (it’s a bit fast to read).  I highly recommend taking an hour to listen to his interview [2]; it’s well worth it.

1. KQED, Interview with Peter Signer, <http://www.kqed.org/.stream/anon/radio/forum/2009/03/2009-03-04b-forum.mp3>
2. Peter Signer, <http://www.princeton.edu/~psinger/>
3. The Life You Can Save, <http://www.thelifeyoucansave.com/>
4. Open Culture, Save a Life in 3 minutes, <http://www.openculture.com/2010/06/save_a_life_in_three_minutes.html>