TerraMGP said:
First, not its not the 'rational conclusion' please don't be so arrogant. Agnosticism is because atheism rules out a facet of reality entirely. I don't want to go on and flame but that kind of arrogant thinking is not progressive.
Second Atheism IS a religion as it is a specific view on reality. It is not a Faith residing in a Deity but it is faith in mans limited current conceptualization of reality and an outlook on the way the universe works. By dictionary definition, its a religion.
Atheism is a single existential claim. Or perhaps a handful of related existential claims. No rituals, no cosmology of its own, no inherent moral code. By itself, "there is no god" is too narrow to be a belief system.
Atheism should be on the list because "religion" is commonly a shorthand for "religion or attitude about religious claims". But, based on what I consider the anthropological or historical idea of a religion, I don't think atheism qualifies. Again: too narrow.
Maybe there's enough commonality within "late-20th-century Western atheists who like to quote Voltaire and Dawkins"(*) for that to be a meaningful group with its own set of distinct traditions and, therefore, a borderline religion. Or maybe "teenage gamers who argue prominently about atheism on an Internet forum". But atheism as a whole or atheists in general? I don't think so.
...
On the more, err, religious point about "rational conclusions":
There's an inherent uncertainty to everything, isn't there?
As pragmatic beings who actually have finite lifespans and things to do, humans are capable of prioritizing these uncertainties and dismissing the trivial ones.
Now, clearly it's worthless to answer
every question with "I don't know" (or "We can't ever truly know"). So we must pick and choose our assumptions.
In rough terms, you want to estimate the probability that each potential assumption (including leaving a question un-decided or declaring it absolutely undecidable) is correct and then assign some kind of utility/disutility to being right or wrong about your particular guess.
Any discussion about probabilities and weights would be quite nuanced. A real "calculation", if at all feasible, would clearly be beyond the power of the human mind.
This is why I think you're jumping the gun when you say that "I don't know" is the only "rational" perspective here.
You can arrive at any conclusion "rationally" depending on what information you have(**) -- this is why, if we ever get into a horribly long argument about the proposed existence of any supernatural stuff, I'm probably going to be spending the bulk of my time trying to offer you new input that I think might sway your estimation of which assumption works best.
There is a very real cost to leaving some questions undecided. That's why I say "I have five digits on my right hand" instead of "I believe that I have five digits on my hand but maybe my hand and my entire reality are an illusion" even though I have, perhaps, occasionally entertained the idea that the latter is correct.
So, given my personal experiences and the range of information available to me, I can say with some confidence that "There is no god" is, by a long shot, the claim that most closely approaches truth. In fact, I think it approaches it so closely that I'm willing to just say "There is no god" instead of "I don't know".
In short (ha, ha):
A "rational" Bayesion decision-making process produces different conclusions based on different knowledge.
False uncertainty is just as bad as false certainty.
-- Alex
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* - For the record, I'll pass on those two guys.
** - Here I feel obligated to rip on Thomas Aquinas, because he's my little metaphorical whipping boy for what happens when pretty excellent logic is mixed with poor initial information. What happens is that you get detailed essays about how devils collect semen.
