From: Robin Hanson (rhanson@gmu.edu)
Date: Wed Nov 03 1999 - 09:52:26 MST
I've been buzy the last two weeks writing a new paper
(http://hanson.gmu.edu/torustwn.pdf or .ps), and just
caught up with this long and interesting discussion
about miracles, and ETIs all around us.
I share Hal's visceral horror of reverting to religion,
but also share Eliezer's insistence that we entertain
any hypothesis, no matter how horrifying.
The main problem with the "ETIs are all around" theories
is that as a whole they fail to predict much of anything.
The alternative class of theories, that the universe is
mostly dead and uncaring, have in contrast led to many
strong predictions, many of which have been dead on.
Postulating a mostly dead universe has led us to expect that
relatively simple mechanisms underly phenomena, and that
these mechanisms are similar across time and space. While
predictions based on these expectations haven't always been
dead on, on the whole they have been remarkably good.
In the space of all logically imaginable observations, the
dead universe theories have, as a whole, assigned a relatively
high likelihood to data we observed, relative to the data
we did not see. In Bayesian terms, relative to theories which
don't assign as high a likelihood to to observed data,
our posterior that the right answer is in this theory class
should rise.
In contrast, the class of living universe theories has not,
as a whole, assigned a very high likelihood to the data we
actually observe. For every more specific theory that predicted
that, say, the allies would win World War II because God is
on their side, another nearly equally plausible theory in
this class predicted the opposite.
This lack of specific predictions seems to result from
saying "they are all powerful and can get whatever they want",
while also being willing to entertain a very wide range of
ideas about what they could want.
I applaud Robert Bradbury's attempt to work some more robust
and specific predictions out of the live universe class of
theories. I'm not yet convinced he has done so, as it seems
he is so far mostly taking the fact that the universe looks
dead to constrain he theories of a live universe. But I look
forward to his collecting his ideas into a coherent paper
for us to evaluate.
On the topic of web invitations, I see that some think that
making a web page inviting ETIs to visit might make such
visits more likely. But I can equally entertain the idea that
it might make them *less* likely to visit. So I can't support
the effort.
Robin Hanson rhanson@gmu.edu http://hanson.gmu.edu
Asst. Prof. Economics, George Mason University
MSN 1D3, Carow Hall, Fairfax VA 22030
703-993-2326 FAX: 703-993-2323
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