As others have mentioned, there’s an interpersonal utility comparison problem. In general, it is hard to determine how to weight utility between people.
I actually don’t think this is a problem for the use case I have in mind. I’m not trying to solve the comparison problem. This work formalizes: “given a utility weighting, what is defection?”. I don’t make any claim as to what is “fair” / where that weighting should come from. I suppose in the EGTA example, you’d want to make sure eg reward functions are identical.
“Deliberately sub-Pareto move” I think is a pretty good description of the kind of “defection” that means you’re being tatted, and “negligently sub-Pareto” is a good description of the kind of tit to tat.
Defection doesn’t always have to do with the Pareto frontier—look at PD, for example. (C,C), (C,D), (D,C) are usually all Pareto optimal.
I actually don’t think this is a problem for the use case I have in mind. I’m not trying to solve the comparison problem. This work formalizes: “given a utility weighting, what is defection?”. I don’t make any claim as to what is “fair” / where that weighting should come from. I suppose in the EGTA example, you’d want to make sure eg reward functions are identical.
This strikes me as a particularly large limitation. If you don’t have any way of creating meaningful weightings of utility between agents then you can’t get anything meaningful out. If you’re allowed to play with that free parameter then you can simply say “I’m not a utility monster, this genuinely impacts me more than you [because I said so!]” and your actual outcomes aren’t constrained at all.
Defection doesn’t always have to do with the Pareto frontier—look at PD, for example. (C,C), (C,D), (D,C) are usually all Pareto optimal.
That’s why I talk about “in the larger game” and use scare quotes on “defection”. I think the word has to many different connotations and needs to be unpacked a bit.
The dictionary definition, for example, is:
A lack: a failure; especially, failure in the performance of duty or obligation.
n.The act of abandoning a person or a cause to which one is bound by allegiance or duty, or to which one has attached himself; a falling away; apostasy; backsliding.
n.Act of abandoning a person or cause to which one is bound by allegiance or duty, or to which one has attached himself; desertion; failure in duty; a falling away; apostasy; backsliding.
This all fits what I was talking about, and the fact that the options in prisoners dilemma are traditionally labeled “Cooperate” and “Defect” doesn’t mean they fit the definition. It smuggles in these connotations when they do not necessarily apply.
The idea of using tit for tat to encourage cooperation requires determining what ones “duty” is and what “failing” this duty is, and “doesn’t maximize total utility” does not actually work as a definition for this purpose because you still have to figure out how to do that scaling.
Using the Pareto frontier allows you to distinguish between cooperative and non-cooperative behavior without having to make assumptions/claims about whose preferences are more “valid”. This is really important for any real world application, because you don’t actually get those scalings on a silver platter, and therefore need a way to distinguish between “cooperative” and “selfishly destructive” behavior as separate from “trying to claim a higher weight to one’s own utility”.
This strikes me as a particularly large limitation. If you don’t have any way of creating meaningful weightings of utility between agents then you can’t get anything meaningful out. If you’re allowed to play with that free parameter then you can simply say “I’m not a utility monster, this genuinely impacts me more than you [because I said so!]” and your actual outcomes aren’t constrained at all.
This just isn’t what I want to use the definition for. It’s meant to be descriptive, not prescriptive.
Similarly, while other definitions of “defection” also exist, I’m interested in the sense I outlined in the post. In particular, I’m not interested in any proposed definition that labels defection in PD as not-defection.
I actually don’t think this is a problem for the use case I have in mind. I’m not trying to solve the comparison problem. This work formalizes: “given a utility weighting, what is defection?”. I don’t make any claim as to what is “fair” / where that weighting should come from. I suppose in the EGTA example, you’d want to make sure eg reward functions are identical.
Defection doesn’t always have to do with the Pareto frontier—look at PD, for example. (C,C), (C,D), (D,C) are usually all Pareto optimal.
This strikes me as a particularly large limitation. If you don’t have any way of creating meaningful weightings of utility between agents then you can’t get anything meaningful out. If you’re allowed to play with that free parameter then you can simply say “I’m not a utility monster, this genuinely impacts me more than you [because I said so!]” and your actual outcomes aren’t constrained at all.
That’s why I talk about “in the larger game” and use scare quotes on “defection”. I think the word has to many different connotations and needs to be unpacked a bit.
The dictionary definition, for example, is:
This all fits what I was talking about, and the fact that the options in prisoners dilemma are traditionally labeled “Cooperate” and “Defect” doesn’t mean they fit the definition. It smuggles in these connotations when they do not necessarily apply.
The idea of using tit for tat to encourage cooperation requires determining what ones “duty” is and what “failing” this duty is, and “doesn’t maximize total utility” does not actually work as a definition for this purpose because you still have to figure out how to do that scaling.
Using the Pareto frontier allows you to distinguish between cooperative and non-cooperative behavior without having to make assumptions/claims about whose preferences are more “valid”. This is really important for any real world application, because you don’t actually get those scalings on a silver platter, and therefore need a way to distinguish between “cooperative” and “selfishly destructive” behavior as separate from “trying to claim a higher weight to one’s own utility”.
This just isn’t what I want to use the definition for. It’s meant to be descriptive, not prescriptive.
Similarly, while other definitions of “defection” also exist, I’m interested in the sense I outlined in the post. In particular, I’m not interested in any proposed definition that labels defection in PD as not-defection.