From: Lee Corbin (lcorbin@tsoft.com)
Date: Sat May 17 2003 - 13:24:50 MDT
Eliezer writes
> > [In the non-iterated Prisoners' Dilemma] *OBVIOUSLY* Doug 2003 should
> > Defect, since he knows that the 1983 version is going to cooperate.
>
> Not if Doug-2003 is also an altruist. There's more than one possible
> reason to cooperate, after all.
Well hell's bells. If that's the case, then why ever Defect?
Listen, the whole idea behind the *entries* in the table is that
they are the payoffs of the players. That's what the numbers
*mean*, the utilities of the players.
Now, although I say that it means you should definitely defect
in almost all cases, I am not the kind of extremist that Smullyan
is, who claimed that he would defect even against his mirror image.
(Was he just trying to be provocative, or did he slip a bearing?)
I say that you should Defect (and that is what the entries in the
table say too) whenever you know what your opponent is going to do.
If you know he is going to Defect, then you Defect. If you know
that he is going to Cooperate, then you Defect. It's right there
in the table.
The highly interesting case is if you don't know what he's going
to do AND his behavior is probably correlated with yours. For example,
I would be afraid to Defect against a physical duplicate if he was
a close (or near) duplicate. After all, whatever thoughts I think
are likely to course through his head as well. But if it any entity
whatsoever, including 1983 versions of myself, then the table says
"Defect".
> From my viewpoint, the only good reason to *defect* is a Tit-for-Tat
> retaliation to maintain social order. Otherwise the calculation is
> very simple; maximum benefit to all sentients is optimized by taking C.
Sure, I'm an altruist too (a lot of the time), and so the payoffs
in the NIPD don't reflect my true payoffs (in many cases), such as
if the table was set up so that if we Cooperate we get our arms
broken, if we mutually defect we get hospitalized for a year, and
if you Defect against my Cooperation you get off scot-free and I
get tortured to death. In that case, I will Cooperate (and hope
that I'm dealing with a good fellow who'll do the same).
> For that matter, Doug-1983 anticipates being Doug-2003, so it's in his
> best selfish interest to cooperate even if he thinks Doug-2003 will
> defect.
I never said that Doug-1983 knows anything about who he's
playing. So far as he knows, it's not his sister, his
friend, or even his future self. He was explicit back in
1983: you could Cooperate because it's superrational to
do so.
In my thought experiment, it's simply clear as a bell that
Doug-2003 must Defect.
> Mixing time travel and the Prisoner's Dilemma sure does make for some
> interesting situations. It can be resolved to mutual cooperation using
> the Golden Law, but only if Doug-1983 can accurately simulate a future
> self who knows his past self's decision. The time-travel oneshot PD can
> also be resolved much more straightforwardly by making a binding promise
> to yourself, using self-modification or a pre-existing emotion of honor.
Yes, there are all sorts of interesting ways to change the numbers
in the boxes as written.
Lee
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