A pro of proportional giving is that it’s dead simple to budget and keep in mind.
It can also get people to give a certain amount continually and keep them emotionally invested in charitable effort, while allowing them plenty of savings for contingencies and perhaps an eventual larger lump sum donation.
And even if it’s not optimal, “indefensible” is a pretty strong claim.
That would be why I put “possibly” in front of it.
For the avoidance of doubt, I agree that it’s simple and works pretty well in practice. That’s why I’m curious whether there’s a good theoretical justification for something like it.
I think you won’t find anything without a lot of assumptions and caveats; Any concave utility function will simply never lead to proportional giving.
But certainly, many people will scale up their own expectations of lifestyle along with their income until a pretty high point: that is, they’ll try to tell you or at least behave as if they don’t have a concave utility function, until they’re well into the six figures (sometimes more). Since income changes are slow and tend to co-occur with many other life changes, this, along with psychological biases, complicate any earnest attempt to sit down and say “I’ll be best off giving X portion of my income this year”.
A pro of proportional giving is that it’s dead simple to budget and keep in mind.
It can also get people to give a certain amount continually and keep them emotionally invested in charitable effort, while allowing them plenty of savings for contingencies and perhaps an eventual larger lump sum donation.
And even if it’s not optimal, “indefensible” is a pretty strong claim.
That would be why I put “possibly” in front of it.
For the avoidance of doubt, I agree that it’s simple and works pretty well in practice. That’s why I’m curious whether there’s a good theoretical justification for something like it.
I think you won’t find anything without a lot of assumptions and caveats; Any concave utility function will simply never lead to proportional giving.
But certainly, many people will scale up their own expectations of lifestyle along with their income until a pretty high point: that is, they’ll try to tell you or at least behave as if they don’t have a concave utility function, until they’re well into the six figures (sometimes more). Since income changes are slow and tend to co-occur with many other life changes, this, along with psychological biases, complicate any earnest attempt to sit down and say “I’ll be best off giving X portion of my income this year”.