To put it in the simplest form, I say that knowledge requires evidence, but believing requires no evidence. Evidence is in the province of science. Belief and language is in the province of philosophy.
The philosophers say that they can prove a negative just by thinking logically about it. They require no evidence. By my definition, not requiring evidence is believing. I do not say their belief is valid or not, just that it is only belief, not knowledge. They contend it is in fact knowledge.
I noticed a lot of activity on this thread lately so I thought I'd step in and see what all the fuss was about... Philosophy, of course.
Now, if this were a scientific topic it would be worded something along the lines of "Can a universe come into existence on its own and organize itself in a manner that forms intelligent life and how can we test it?" Then at some point if the answer to that question was yes, then the next question is, "Can the forces that created such a universe be reproduced or manipulated?". We haven't even reach a point that this topic can reasonably be asked.
So, to all the philosophers out there... enjoy a small bit of the playful criticism from one of the most eloquent critics of philosophy.
--Philosophers say a great deal about what is absolutely necessary for science, and it is always, so far as one can see, rather naive, and probably wrong.
--We can't define anything precisely. If we attempt to, we get into that paralysis of thought that comes to philosophers… one saying to the other: "you don't know what you are talking about!". The second one says: "what do you mean by talking? What do you mean by you? What do you mean by know?"
I feel comfortable in saying that I know there is no god because I feel there is sufficient evidence to support that hypothesis and an utter lack of any to the contrary.
For me, sufficient evidence is enough. The lack of concrete proof in this circumstance is irrelevant, unnecessary, and leads to such time-wasting hypothetical pursuits as pondering alternate universes rather than living in the here and now. Life is too damn short to waste daydreaming about "what if."
I realize that evolution does not disprove the existence of god, but it utterly destroys creationism (see Q3 here to understand what I'm getting at). And the notion that a god could steer the process of evolution (as some believers want to believe) is absurd: it's natural (not supernatural) selection, stupid!
But evolution alone doesn't disprove the existence of god (Q5 from the FAQ). Religion takes the final steps toward doing that. Religious texts are so inwardly contradictory (in and of themselves) and so outwardly contradictory (to what science has shown us to be true, for example) that they are preposterous to anyone, of any age, capable of rational thought.
What we're left with if not atheism, then, is deism or spiritualism. The problem I have with these beliefs is explained in my second paragraph: I regard them as glorified daydreaming, no more, no less. My opinion is that those that take the position that "I don't believe in religion but I do believe in god" are clinging to that belief rather than examining the evidence with any degree of real effort. If you want to waste your life doing that, then go right ahead. But for me, reality is too damn interesting to pass by. I'd rather think about what is rather than what I'd like there to be.
Finally, I for one do not "trust scientific fact and reasoning" as OP puts it, and I don't recommend anybody does. I doubt it all the way. Science and scientists have been wrong in the past. They will be wrong again. But there is built-in self-correcting machinery: knowledge evolves. Perhaps the most beautiful thing about science is that it does not require belief in order to work. In fact, I have found that doubting it (this is different than denying it, I should add) makes it work best.
Hypothesizing is a human thing to do; it's part of the thinking process. But remember that theories evolve when there is lack of any contradictory evidence to an hypothesis: they fail to be dis-proven. Neither "god does not exist" nor "god exists" have been disproven concretely, but only one of those statements has any supporting evidence that has withstood intense scrutiny.
I think that belief in science is venomous. I feel that belief is antithetical to the Scientific Method. Beliefs opinions are like assholes. Just the facts, ma'am.
A quick clarification and I'm done. In the last paragraph I was equating belief and trust.
I also wanted to add that it's dangerous to believe in science. That's how frauds (homeopathy anyone?) continue to survive.
... but my edit timer ran out.
Being logically impossible says what definitely can't exist.
I contend that something that is impossible is just a way to say that the Identity (definition) is wrong and, yes, it can't exist. But scientifically your Identity is just a hypothesis. If your hypothesis states that hell cannot exist, how do you go about scientifically proving it? Saying that hell is impossible due to the processes laid out by logic, is saying that science cannot touch where logic treads.
I give up trying to get you folks to see where I am coming from, so I will say this:
Logically (in our thoughts) you can call something impossible meaning it cannot exist, but scientifically (using evidence of the real world) you can never say with 100% certainty that anything doesn't exist.
Will that satisfy you?
I doubt it. I think that your thoughts are more real to you than the real world.