[extropy-chat] Peak Oil meta-news

[Rafal Smigrodzki]

On 3/8/06, Eliezer S. Yudkowsky <sentience at pobox.com> wrote:
> Robin Hanson wrote:
> > At 08:10 AM 3/8/2006, Lee Corbin wrote:
> >
> >>I venture to say that anyone who's studied Gold's fine book
> >>will significantly change his odds more towards the abiotic
> >>theory, (even if he retains probability at less than
> >>fifty percent).
> >
> > This can only be true on average for rational people if they do not believe
> > your claim.   If I believed you that my odds would go up after reading the
> > book, I would just raise my odds in anticipation of that, even if I never read
> > the book.   If I am rational, I must expect that reading a book arguing for
> > a position on some subject will be as likely to move me away from that
> > position as to move me closer.  (More precisely my expected value of
> > my future expectation must equal my current expectation.)
>
> Robin, this is true, but I fear the way you phrased it may confuse
> people.  They may visualize picking up Gold's book, on Lee's
> recommendation, and being forced to believe that Gold's book, which
> contains many arguments *for* abiotic oil, must necessarily have a
> significant probability of leaving them *less* convinced of abiotic oil
> than they were before they ever heard of Gold's book.
>
> What actually happens is this:
>
> 1)  I assign some small probabiility to abiotic oil, say, 20%.
> 2)  I hear Lee recommending Gold's book.
> 3)  I now assign some probability, say 30%, to Lee's assertion that if I
> read Gold's book, I would assign a greater probability to abiotic oil,
> such as 80%.
> 3a) This involves taking the probability of a probability, which
> involves thorny issues of reflectivity which I'm still trying to work
> through, such as empathizing with your future self and granting credence
> to a purely abstract computation.
> 3b) If you permit the notion of a probability of a probability, it is
> clear that the variance in my expected future probability assignment has
> increased.
> 4) The actual distribution over my future probability assignment now has
> two spikes; a spike at 20% and a spike at 80%.  My *expectation* will
> lie somewhere between these two points.
> 5)  I read Gold's book and find it has no convincing favorable
> arguments.  My opinion is now unchanged relative to what it was at the
> start of the analysis, 20%.  This was always my dominant opinion, and
> has not changed; however my *net expectation* briefly rose and then
> settled back down.

### If you read Gold's book and find no good arguments, shouldn't your
expectation drift below 20%, since the absence of evidence in a
location where it is most likely to be found is a form of evidence for
absence (i.e. the null hypothesis)?

Rafal