On Tue, 5 Jan 1999, Wei Dai wrote:
> On Sun, Jan 03, 1999 at 07:32:09PM -0500, Jacques M Mallah wrote:
> > Wrong. It is not true that no matter what I decide, I will have
> > the same utility. What is true is that only one decision is possible in
> > this particular case. I just don't know which one yet.
>
> Why is it wrong? Didn't you say earlier that in a theory with no free
> parameters all possible courses of action must occur? Why do you now
> say only one decision is possible? I'm having a lot of
> trouble understanding this reply.
Yes, I did say that. But it's not really the relevant issue,
more of a red herring. Remember, when I said that, I was still toying
with the notion of subsystems, which are now clearly seen as irrelevant.
Although some me-like beings will make each of the
possible decisions, it is true that in this particular case, that is,
considering only the very me-likest cases, I will only make one. (In
terms of computations, that is, computations that are exactly identical to
mine have the same outcome.)
But really, you don't need to get that specific if you just
substitute the idea that the effective probability of making each
decision is determined by me-like mental processes. Hopefully this will
become clear to you.
> > I'll say it again: my mental processes *are* the laws of physics
> > in action, and *do* have consequences. My choice *does determine* the
> > actual utility, which is to say, the laws of physics determine it.
> > I can't overemphasize the above point. Stop and think about it
> > if you feel tempted to just keep reading.
> > Forget I said anything about subsystems. I'm sorry; I was wrong
> > to have done so. Utility functions are defined over any hypothesized
> > state of the universe. It is redundant to say it is defined over a global
> > state: that is true by definition.
> > In general, they only depend on the (unnormalized) measure
> > distribution of consciousness, since why should I care about anything
> > else? Any hypothesized situation where I can calculate how many
> > computations of each type would be implemented should give me the utility
> > function for that situation.
>
> I'm with you so far.
Good.
> > Even if a hypothesis is not truly self consistent, an
> > approximation to that hypothesis can be, and is the best I can do. Since
> > we know I won't be able to show which decisions are unphysical a priori,
> > my most accurate approximate calculated utility for that hypothesis is a
> > well defined quantity. It is however a function of who I am.
> > It is also true that, assuming I pick the choice with the highest
> > utility, and that my calculations are correct, that the actual utility
> > will be that highest value.
> > So another way to look at it is that to calculate the actual
> > utility, I have to also calculate a bunch of other values as an
> > intermediate step. Then I should decide to do what I've just shown that
> > the laws of physics make me do under those assumptions.
>
> Now I'm lost. I have no idea what the above three paragraphs mean.
Why not? It is should be clear why I said that in a theory with
no free parameters, a scenario in which I make a decision other than the
one I really will make is unphysical. This is assuming I make only one
decision - outcome. The two next paragraphs refer to that as well.
If you want to consider the case where I have an effective
probability to make each decision, that works too, though I couldn't
calculate the actual utility then.
The important point is that I make decision A instead of decision
B, that does (partially) determine the true utilty. If there are 100
copies of me, and 90 others choose A and 9 others choose B, the decision
that the 100th copy - or me myself, if you want - makes does have an
effect.
The confusing issue - and I don't blame you, I didn't realize it
immediately either - is that an external observer might calculate and say
'there are 100 copies of him, and according to the laws of physics, which
have no free parameters, 90 copies choose A and 10 copies choose B.'
This creates the temptation to say to myself, that I can't really
affect the utilty, I can only choose which camp to place myself into in
that predetermined vote. BUT THAT IS NOT TRUE. The laws of physics
determine the utilty, and my mental processes are the laws of physics in
action, and to say that the vote could not have been otherwise is merely
to say that my mental processes, or the 100 variations of it (effective
probability distribution), could not have been otherwise.
Whatever computation my mental processes correspond to, they will
produce the result of that computation. That is true regardless of
whether the computation is the result of the laws of physics alone, or the
laws of physics + particular free parameters. There is no reason that the
identical computation, or identical effective probability distribution of
such computations, could not occur for both of those possibilities.
To say that I affect the outcome is to say that my mental
processes, or computation, determines the result, which is still true.
And the utility function, for my decision making, must be calculated by me
with different scenarios for each possible decision-outcome, because I do
not know what my own computation is.
> > I'm not sure how to define it in a language-independent way. It
> > probably can't be done, which would pretty much guarantee the truth of
> > my belief that it can't have a well defined value that is equal to zero.
>
> Now that I think about, it doesn't make sense to have a theory with zero
> information content. It should be the universe that has zero information
> content. The theory should define what information content means, and then
> simply state that the actual universe is the unique universe that has zero
> information content.
Would such a theory be unique? If so, and I doubt it but would
like it to be true, it would make sense to speak of information content as
a well defined quantity.
Then we would have a mathematical theory of information content,
as well a theory of physics. The theory of physics, however, would have
zero information content, as defined by the other theory.
- - - - - - -
Jacques Mallah (jqm1584.domain.name.hidden)
Graduate Student / Many Worlder / Devil's Advocate
"I know what no one else knows" - 'Runaway Train', Soul Asylum
My URL:
http://pages.nyu.edu/~jqm1584/
Received on Wed Jan 06 1999 - 11:08:30 PST