The Parasite Dilemma

[Silent A]

There are 99 other people. A little algebra will show that if 67.6667 of them are contributors than you do just as well being a parasite or a contributor.

Therefore, if you have reason to believe that 68 or more of them will contribute then you're better off being a parasite.

In other words, if most of the other people are Americans, you should contribute. Otherwise, be a parasite. [img]/images/graemlins/laugh.gif[/img]

ETA: oops, did the math wrong. I'll post the correct answer in a couple minutes.

ETA part 2: correct math changes the indifference point to about 67.68 contributors (i.e. no real difference at all).

[knowledgeORbust]

[ QUOTE ]

You are all motivated to make money.


[/ QUOTE ]

If this is the only known information, I'm going with contributor. Whatever the case, I don't think there's going to be much money in the fund.

Interesting stipulation: is there any record of the choices individuals made after the fact? If yes, are participants aware of this beforehand?

[PairTheBoard]

[ QUOTE ]
Interesting stipulation: is there any record of the choices individuals made after the fact?

[/ QUOTE ]

No. So no peer pressure is involved.

PairTheBoard

[Nicholasp27]

note: u only wanna go parasite if 31 or less people go parasite...so it's <1/3 as the cutoff point


if 32 go parasite, 67 go contributor...now my choice:

i go parasite: 6700-6600=100; 33*2+67=133 shares

2/133 * 100 = $1.50 for me


i go contributor: 6800-6400=400; 32*2+68=132 shares

1/132 * 400 = $3.03 for me

so it's <=31, not <=1/3 that matters

[PairTheBoard]

[ QUOTE ]
note: u only wanna go parasite if 31 or less people go parasite...so it's <1/3 as the cutoff point


if 32 go parasite, 67 go contributor...now my choice:

i go parasite: 6700-6600=100; 33*2+67=133 shares

2/133 * 100 = $1.50 for me


i go contributor: 6800-6400=400; 32*2+68=132 shares

1/132 * 400 = $3.03 for me

so it's <=31, not <=1/3 that matters

[/ QUOTE ]



Regardless, you don't know what everybody else is going to do. That's what makes it a game. The question remains, what do you do?

I suspect the correct game theory answer is to randomize your choice. Give yourself 1/3 chance to pick Parasite and 2/3 chance to pick Contributor.

If that's correct, and everybody does that then Game Theory ensures an average result of Break Even for everybody. I believe this shows Game Theory to be lacking in some kind of Rationality which has probably not yet been well defined by the professional Theoreticians. Clearly, everyone does better if they all reject Game Theory and decide to be Contributors.

I think this is more than just a theoretical curiousity. It goes to the heart of a lot of phenomenon which allow society to work better than game theory predicts. I also think it is a mistake to blindly promote the mentality of the parasite as logically superior - something I see as almost a given for many on this Forum. While looking out for self interest is important, there can also be benefits to supporting the dynamics of the Group. In my view a Balance between the two is the healthy operating perspective.

Extremism in favor of the Group can lead to self destructive fanaticism, while Extremism in favor of self interest can lead to the life of the criminal or sociopath.

PairTheBoard

[vhawk01]

If there are greater benefits to be had by looking out for the well-being of the group, rather than looking solely after your own self-interest, then...well....you might have to define your terms a little. I think your mixed up. This doesn't show the superiority of group-centered behavior, it just provides and example of where self-centered and group-centered are identical.

In fact, even the way you phrase your insight belies the error and diminishes the revelation. You claim that a better result is achieved by everyone rejecting 'self-interest' and picking contributor. A better result for whom? For the individuals? Thats how we both keep score in these things, right? So you are claiming there are better ways of achieving self-interest than self-interest...that doesn't seem to argue against self-interested strategies at all.

[PairTheBoard]

[ QUOTE ]
you might have to define your terms a little.

[/ QUOTE ]

I leave it to the professional theoreticians to do that.

[ QUOTE ]
I think your mixed up.

[/ QUOTE ]

I would be if I let you define my terms for me.

PairTheBoard

[CallMeIshmael]

PTB,

he brought up a very important point, and your response was certainly glib, at best.

You say that everyone does better if they all contribute, but, why do I care? Why does it matter if other players do well? I just care about how I do. (If you want to introduce an empathy element to the payoff, thats OK, but Im assuming we are working under the typical assumption that this has not been done)

If I feel everyone is going to contribute, why wouldnt I play parasite?



(also, Vhawk, self-centred and group-centred strategies dont align here. They are a mixed strategy and pure-contribute, repsectively)

[PairTheBoard]

[ QUOTE ]
If I feel everyone is going to contribute, why wouldnt I play parasite?


[/ QUOTE ]

Because of a reason you haven't thought of. A reason that depends on creative thinking. A reason that takes you outside your box of logic. A reason that the professional theoreticians are still working on formulating. A reason you will never discover unless you look for it.

PairTheBoard

[ctj]

[ QUOTE ]
[ QUOTE ]
If I feel everyone is going to contribute, why wouldnt I play parasite?


[/ QUOTE ]

Because of a reason you haven't thought of. A reason that depends on creative thinking. A reason that takes you outside your box of logic. A reason that the professional theoreticians are still working on formulating. A reason you will never discover unless you look for it.

PairTheBoard

[/ QUOTE ]

It seems to me that you are complaining that game-theoretical analysis of a 1-time Prisoner's Dilemma doesn't apply to iterated Prisoners' Dilemmas. Pure parasite strategies tend to do very badly in iterated scenarios.