[extropy-chat] Superrationality

[Hal Finney]

Lee Corbin writes:
> I have one question. Suppose that today Hofstadter suddenly a time machine,
> and decides to visit the year 1983. He then finds himself in a sealed room,
> with his 1983 version in an adjacent sealed room. All each know is that
> they're in a one-shot PD with each other, and each knows the year from which
> the other comes.
>
> Our Doug, (Doug 2006) consults the payoff matrix.  It says
>
>      (5,5) | (0,10)
>      (10,0)| (1,1)
>
> It is clear what the 1983 Doug will do. What move should our
> Doug play in order to maximize his payoff?

It's funny that you should word the question like that, since there is
a fundamental ambiguity in the word "his" in this situation.  We might
argue that cooperating will maximize "his", Douglas Hofstadter's, payoff,
making it 5+5=10, with 5 coming earlier and therefore, due to discounting
and inflation, worth more.  Or we might interpret it to be asking what
will maximize Doug-2006's payoff, in which case defecting would serve.

One problem with this time-machine variant is that it raises a causation
paradox.  Wouldn't Doug-2006 remember being visited by a future version
of himself, back in 1983?  Wouldn't he remember how that future self had
played, and in that case, wouldn't he be forced to play the same way
this time?  Perhaps we can get around this by assuming that the 1983
version submitted to localized amnesia, forgetting the details of the
incident; or else we could use a model of time travel where a new time
line is formed when the future person reaches the past.

I can't speak for Hofstadter, of course, but ignoring these complications
I strongly suspect he would cooperate in this situation.  We know he
found the reasoning compelling enough in 1983 to make quite an issue
of it.  If he still feels that way, he will play the same.  If not,
I imagine that out of solidarity and sympathy for his earlier self,
he will show respect for the person he was and continue to follow that
principle.  How many of us might be more motivated to follow through on
our commitments, plans and dreams, if we could somehow be confronted by
our younger selves and called to account for how we had lived our lives?

Hal