What Is Fairness? - Cardinal
Let's suppose that person A and person B are sitting together in a
room when an angel appears in a burst of light and says "Be not
afraid! Here are 100 grapes for your enjoyment - divide them fairly
between the two of you, and then consume them." Then the angel
vanishes.
How should A and B divide the grapes? As it happens, person A likes
grapes twice as much as person B does. (For the purists, assume
that each of them has constant marginal utility and that these
facts are commonly known.) The following dialogue ensues:
A: In order to divide them fairly, we should split the grapes
evenly - 50 to you, 50 to me.
B: That's not a fair division: I like grapes half as much as you,
so if we split 50-50, I only end up half as happy as you are. A
truly fair division would make us equally happy. Therefore, I
should get 66 grapes, and you should get 34.
A: That's ridiculous! It can't be fair to give fewer grapes to the
person who likes them more. Our
individual happiness is irrelevant - fairness means splitting the
grapes evenly, nothing more.
B: How can our individual happiness be irrelevant? The whole point of having the grapes is to
makes ourselves happier. It's the quantity of grapes that is
irrelevant here - neither of us cares about how many grapes we get
except through how much utility we will gain from eating them. Our
happiness is the relevant concept to equalize here.
My take: B is right in that happiness is the relevant quantity, but
this notion of fairness verges upon the absurd when one person has
much lower utility for an item than the other. A is confused to
think that fairness is in any way connected with efficiency. I
think that fairness is a concept that is often devoid of a coherent
meaning, even though people often feel very strongly about it. I'd
advise avoiding the question "What is fair?" and instead
considering practical questions like "What has been agreed?" and
"What is practically achievable?"
Conclusion: The two fight for hours over the fair way to divide the
grapes, finally deciding that the only allocation that was fair
under both their definitions was for each of them to have no
grapes. Or A divides, B chooses. That's fair. 