[extropy-chat] Indexical Uncertainty

[Robin Hanson]

At 02:37 PM 10/17/2006, Chris Hibbert wrote:
> > We are the sort of creatures who usually are not very uncertain about
> > who we are.   Nevertheless, we are not completely certain either, and
> > so we often have at least small degrees of indexical uncertainty.
> > So once you accept the basic concept, then the question is when and
> > where it is reasonable to apply the concept.
>
>A somewhat plausible example of uncertainty of identity: a standard
>nightmare supposedly has people waking up thinking that the final exam
>is today and they haven't studied.  That's a Monday-me vs. Tuesday-me
>distinction that can matter intensely.  (Or so I've heard.)
>Anyway, back to the uncertainty.  Unless someone is verging on amnesia,
>the only kind of waking confusion that makes sense is momentary
>confusion about what history-of-behavior you have.  ...

The main reason to be interested in and think about indexical uncertainty
is not because people in our world often have large degrees of such
uncertainty.   The reason to be interested is that it opens up a new family
of counterfactuals to reason about.   Postulating and applying rationality
constraints that relate the reasonable beliefs under different counterfactuals
is a powerful way to constrain the beliefs we should find reasonable.

I find the kind of possibilities considered in Doomsday arguments reasonable,
even if I might take issue with assumptions made about reasonable priors, etc.



Robin Hanson  rhanson at gmu.edu  http://hanson.gmu.edu
Associate Professor of Economics, George Mason University
MSN 1D3, Carow Hall, Fairfax VA 22030-4444
703-993-2326  FAX: 703-993-2323