Yes, agnosticism is a more tenable position to the extent that its
claim is less strong than positive atheism. Atheism, however, does
not presuppose omniscience. This will be in the Virus FAQ, but until
then here's an excerpt from the (excellent) introduction to alt.atheism
FAQ at http://freethought.tamu.edu/news/atheism/intro.html :
"But isn't it impossible to prove the non-existence of something?"
There are many counter-examples to such a statement. For example,
it is quite simple to prove that there does not exist a prime
number larger than all other prime numbers. Of course, this deals
with well-defined objects obeying well-defined rules. Whether
Gods or universes are similarly well-defined is a matter for debate.
However, assuming for the moment that the existence of a God is not
provably impossible, there are still subtle reasons for assuming the
non-existence of God. If we assume that something does not exist, it
is always possible to show that this assumption is invalid by finding
a single counter-example.
If on the other hand we assume that something does exist, and if the
thing in question is not provably impossible, showing that the
assumption is invalid may require an exhaustive search of all possible
places where such a thing might be found, to show that it isn't there.
Such an exhaustive search is often impractical or impossible. There is
no such problem with largest primes, because we can prove that they don't
exist.
Therefore it is generally accepted that we must assume things do not exist
unless we have evidence that they do. Even theists follow this rule most
of the time; they don't believe in unicorns, even though they can't
conclusively prove that no unicorns exist anywhere.
To assume that God exists is to make an assumption which probably cannot
be tested. We cannot make an exhaustive search of everywhere God might
be to prove that he doesn't exist anywhere. So the sceptical atheist
assumes by default that God does not exist, since that is an assumption
we can test.
Those who profess strong atheism usually do not claim that no sort of God
exists; instead, they generally restrict their claims so as to cover
varieties of God described by followers of various religions. So whilst
it may be impossible to prove conclusively that no God exists, it may be
possible to prove that (say) a God as described by a particular religious
book does not exist. It may even be possible to prove that no God described
by any present-day religion exists.
In practice, believing that no God described by any religion exists is very
close to believing that no God exists. However, it is sufficiently different
that counter-arguments based on the impossibility of disproving every kind of
God are not really applicable.
-- David McFadzean david@lucifer.com Memetic Engineer http://www.lucifer.com/~david/ Church of Virus http://www.lucifer.com/virus/