I think you can ask the same question about any fair division question, and I really don’t know how to answer that.
Perhaps is the answer is that we are optimizing for how fair our morality says the division is.
If you are asking humanity, give the money to charity.
If I was one of the two people involved, I’d suggest using the 20 dollars to buy us both dinner (or other jointly enjoyed purchase...charity still works). The social trick leaves neither indebted to the other—in fact it can strengthen the bond.
You can’t come up with a general solution to division problems, because human morality doesn’t work that way. We’ve got really idiosyncratic notions of fairness, especially in cultures which have property rights.
Step 1: Before anything else, let’s get the normative question out of the way. What exactly is the goal here...i.e, what are we maximizing for?
I think you can ask the same question about any fair division question, and I really don’t know how to answer that. Perhaps is the answer is that we are optimizing for how fair our morality says the division is.
If you are asking humanity, give the money to charity.
If I was one of the two people involved, I’d suggest using the 20 dollars to buy us both dinner (or other jointly enjoyed purchase...charity still works). The social trick leaves neither indebted to the other—in fact it can strengthen the bond.
You can’t come up with a general solution to division problems, because human morality doesn’t work that way. We’ve got really idiosyncratic notions of fairness, especially in cultures which have property rights.