Rich <someone@somewhere.com> wrote in message news:<4096BAF0.9050408@somewhere.com>...

I'm reminded of discussions I had with an ex-roomate
who was into magic. Despite a tower of theories explaining
why magic works (you know, like that it causes the wave-
function to collapse), he was somewhat aggravated when
I suggested that first he needed to show *that* magic
worked. Oddly, for as yet unexplained reasons, he was
never able to show me this, or point to anyone who could.

SETI is in a similar position near as I can tell.

Utterly wrong.  SETI is not about finding extra-terrestrial 
civilizations per se, it is about scientific research into
the abundance and nature of extra-terrestrial civilizations.
Failure to find strong evidence of ETI in any given SETI 
program is not a failure of the program, it is a scientific
*result*.  Sufficiently well constructed and well executed
SETI programs that produce a negative result provide 
critical data defining boundaries on the abundance and 
nature of ETIs.  To obtain hard boundaries on ETI parameters
it will be necessary to perform a wide variety of robust
search programs using a wide assortment of techniques (not 
just searching for radio waves but also searching for 
other incidental signs of ETI activity).  But in order to
eventually conduct ALL those investigations it is necessary 
to conduct each of them.  In other words, the only way to
build something whole and of substance is to build it with
bits and pieces which are each incomplete.  Which is what
we are starting to do now with our limited, incomplete
SETI programs.

Compare this with extra-solar planet studies.  Long before 
the 1990s there had been many extra-solar planet searches.
They all were very limited and they all came up empty.
This placed certain upper limits on the abundance and size
of extra-solar planets, but did not at all rule out the
possible existence of planetary systems below the 
detectability thresholds of those studies.  Indeed, as 
better systems and new search techiques were developed
we started to find a large number of extra-solar planets.
And those searches were good enough to allow us to make
informed estimates of various upper and lower limits and
abundances and such-like.  But they have not yet given us 
the entire picture, and it will take more effort and 
different searches to ferret out the information in other
areas to give us a more complete picture.  Again, we have
to do each search in order to do all of them, and though
each may be incomplete and limited, each provides useful
data which forms an important *part* of the bigger, 
better picture.

Or, compare with estimates of the Hubble constant and the
age of the Universe.  There was a time not too long ago
when the data was so poor that estimates of the age of the
Universe differed by a factor of 10.  Even as recently as
the 1990s estimates ranged over a factor of 2.  Now it's
down to about +/- 20% or so.  But in order to get that 
level of knowledge we had to start at a much poorer level 
and work our way up inch by inch through one investigation
after the next.  This is the nature of science, and SETI is 
just another example of that process.