It’s a combination of evidential reasoning and norm-setting. If you’re playing the ultimatum game over $10 with a similarly-reasoning opponent, then deciding to only accept an (8, 2) split mostly won’t increase the chance they give in, it will increase the chance that they also only accept an (8, 2) split, and so you’ll end up with $2 in expectation. The point of an idea of fairness is that, at least so long as there’s common knowledge of no hidden information, both players should agree on the fair split. So if, while bargaining with a similarly-reasoning opponent, you decide to only accept fair offers, this increases the chance that your opponent only accepts fair offers, and so you should end up agreeing, modulo factors which cause disagreement on what is fair.
Similarly, fair bargaining is a good norm to set, as, once it is a norm, it allows people to trade on/close to the Pareto frontier while disincentivizing any attempts to extort unfair bargains.
It’s a combination of evidential reasoning and norm-setting.
I see the norm-setting, which is exactly what I’m trying to point out. Norm-setting is outside the game, and won’t actually work with a lot of potential trading partners. I seem to be missing the evidential reasoning component, other than figuring out who has more power to “win” the race.
with a similarly-reasoning opponent
Again, this requirement weakens the argument greatly. It’s my primary objection—why do we believe that our correspondent is sufficiently similarly-reasoning for this to hold? If it’s set up long in advance that all humans can take or leave an 8,2 split, then those humans who’ve precommitted to reject that offer just get nothing (as does the offerer, but who knows what motivated that ancient alien)?
It’s a combination of evidential reasoning and norm-setting. If you’re playing the ultimatum game over $10 with a similarly-reasoning opponent, then deciding to only accept an (8, 2) split mostly won’t increase the chance they give in, it will increase the chance that they also only accept an (8, 2) split, and so you’ll end up with $2 in expectation. The point of an idea of fairness is that, at least so long as there’s common knowledge of no hidden information, both players should agree on the fair split. So if, while bargaining with a similarly-reasoning opponent, you decide to only accept fair offers, this increases the chance that your opponent only accepts fair offers, and so you should end up agreeing, modulo factors which cause disagreement on what is fair.
Similarly, fair bargaining is a good norm to set, as, once it is a norm, it allows people to trade on/close to the Pareto frontier while disincentivizing any attempts to extort unfair bargains.
I see the norm-setting, which is exactly what I’m trying to point out. Norm-setting is outside the game, and won’t actually work with a lot of potential trading partners. I seem to be missing the evidential reasoning component, other than figuring out who has more power to “win” the race.
Again, this requirement weakens the argument greatly. It’s my primary objection—why do we believe that our correspondent is sufficiently similarly-reasoning for this to hold? If it’s set up long in advance that all humans can take or leave an 8,2 split, then those humans who’ve precommitted to reject that offer just get nothing (as does the offerer, but who knows what motivated that ancient alien)?