We are in full agreement with respect to gravity. It's not a fact, which can easily be shown since it is a noun. Gravity makes the Earth rotate around the Sun, is a fact, just as a falling Apple made Newton contemplate about gravity, is a fact. Whether an apple actually fell on his head may be an untrue fact.
Now to your definition of fact:
I hold the view that a "fact" is nothing more or less than a proposition that has been expressed by some person in a language.
Let's look at two propositions expressed by some person in a language:
Ken said: "Lee Harvey Oswald killed John F. Kennedy"
Niels said "Lee Harvey Oswald vermoordde John F. Kennedy"
Note: "vermoordde" is the Dutch equivalence of "killed", and in this particular context has exactly the same meaning.
Obviously the two statements are not equal, one is expressed by a person named Ken, the other by a person named Niels, and they are even expressed in different languages, yet they both make the same factual statement about the killer of John F. Kennedy.
I would say therefore that a fact is nothing more and nothing less than a proposition, irrespective of who said it, and in what language it is stated.
killed(Lee Harvey Oswald, John F. Kennedy) = "Lee Harvey Oswald killed John F. Kennedy" = "Lee Harvey Oswald vermoordde John F. Kennedy"
That said, the statement "Lee Harvey Oswald killed John F. Kennedy" is only a proposition in particular contexts, and within those contexts can even have different truth values.
In the here and now it is a proposition, and we may say it to be true (depending on whether one accepts the official reading or not).The statement is also a proposition, but pertinently a false one in a context between 18 October 1939 and 22 November 1963. Before 18 October 1939, the day Lee Harvey Oswald was born, it is not even a proposition because the term Lee Harvey Oswald is undefined.
Even though a fact is independent of the person stating it and also independent of the language it is stated in, it is not independent of the context in which it is stated.
Sometimes the context in which a proposition is true is kept implicit, but sometimes we want to be very explicit about these contexts and at least have them supported in the database we are going to store facts in.
Since we can derive a database schema from ORM's conceptual model, it would be nice if we could either model these contexts, or at least mark facts as applying to a certain context.
As to your statement about whether organizations believe something to be true, we can easily fix that by saying the CEO of an organization believes something, and if he doesn't personally have any beliefs about a fact, he has delegated that to someone else in the organization. Therefore the highest ranking person holding a certain belief about a fact represents the organization and with that gives the organization a particular belief.