What if we were all wrong?
What if our reasons were flawed.
Would nothing be a fact?
If we have established something as a fact, yet are mistaken, then our methods of arriving at a consensus regarding the evidence supporting the fact are flawed and we must develop a new method. Fortunately we've gone through this process already throughout human history and we have arrived at the scientific method which is the best and most accurate way of determining truth. Short of waxing purely philosophical, and venturing into areas of solipsism, we likely aren't going to come to any better method than we use now.
No we don't.
Unless of course something can change from non fiction to fiction which wouldn't make sense.
As you said. Something believed to be non fiction does not make it non fiction.
Same goes for fiction?
(Refer to your post to moon)
Sure we do. The first mentions of our concept of pixies comes from fictional tales. Perhaps they are loosely based on some observation, however they have existed solely in fiction since their inception. Perhaps some day we will find one, but until that time we must consider them fictional, or at the very least as an unknown entity.
And no, we are not going to change something from non-fiction to fiction, since if it is real then it will always be real. Dinosaurs are not fiction simply because they don't exist anymore, they still are based in fact.
However fiction can become non-fiction. Let's use your pixies as an example. Up until today they have existed solely in fictitious tales. However if I run down to the lab and make one, then they are no longer fiction.
Just like what I said about religion. As of now each religion must be considered fiction as it is unproven. If such a time comes that some religion is proven to be a fact then it will become non-fiction, but until that day we cannot assert that any one is true.
It is still evidence. How much is sufficient is something we could argue about for years. You could watch something one billion times and it could never be sufficient.
It is in a sense, however it is a very fallible source of evidence. Simply because we see something does not mean it is real. People have hallucinations all the time, and also the brain will frequently make up images to explain to itself something which it does not understand. This is why visual evidence must be observable, demonstrable, and repeatable.
If I see a pixie but no one else does I cannot say that I saw one. However if there are 20 of us hanging out, everyone is in a unaltered and cognizant frame of mind and we all see a pixie then there might be something to it. If the pixie tells us to come back tomorrow, and we do and bring 50 friends and we all see the pixie, then it's a safe bet that it's real.
However all of this observation alone is still not sufficient proof to make it a fact. For that we need tangible evidence. A video recording, blood sample, photographs, things of that nature would likely be moving into the territory of proof.
What if you did not believe nor not believe.
Sorry to bring religion into this but like agnostics.
Not exactly sure what you mean by this.
This is as logical as any theory if you think about it.
Also is there an example of when not seeing can be a source of evidence?
Actually the mice idea you are referring to is not a logical hypothesis at all. We already know for a fact when and how mice and cats came to be, and it is not possible that a mouse created the earth or cats.
And yes, not seeing can be a source of evidence, yet it is just as difficult to use as proof as seeing. If one person says something is supposed to be in a place, yet no one sees it, it doesn't mean that it doesn't exist (like God) but it does mean that either the person making the claim doesn't understand the nature of what their pointing out, or that something else is at work which precludes observation.
While not seeing something doesn't mean that isn't there, it typically means that it's far more likely that it's not than is, just like observation alone cannot prove something, but it most certainly tips the scales in favor of that thing being real.
