When we think and later express in works can it be anything else but an opinion, a summary of perceived learning and experience? Facts? There are more disproved facts in science than accepted ones. When two or more people are in agreement, do the individual opinions turn into one fact? Repeating something, which has come from a reputable source, is this make it a fact? Is its origin not still the opinion of the person behind the reputable source?
closed as unclear what you're asking by Ram Tobolski, Keelan♦, James Kingsbery, jeroenk, virmaior Apr 24 '15 at 14:40
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It's not super clear what you're asking, but I'll take a stab at it. It looks like you're interested in finding out what makes something a fact. I'll deal with your question directly, and then provide some comments to point you in the right direction.
When we think and later express in [words] can it be anything else but an opinion, a summary of perceived learning and experience?
We can utter sentences without endorsing the propositions expressed by those sentences. Similarly for what we think. So not everything we think or say is an opinion. For instance, suppose I utter "it is raining outside," even though I believe that it is not raining. I can say it, but that doesn't mean I endorse/believe it.
When two or more people are in agreement, do the individual opinions turn into one fact
Not in general. Sharon and I may both hold the opinion that the Earth is flat but that doesn't entail that the Earth is flat. Also your terminology here is a bit weird. Even if someone's opinion is correct it's not as if it 'turns into' a fact - nothing like a transformation of the opinion happens. Rather, opinions express or correspond to facts just when the proposition expressed by the opinion is true (very roughly).
Repeating something, which has come from a reputable source, is this make it a fact?
No. In general the fact (sorry) that a reputable source said P doesn't make it true that P (barring cases where P is a claim about being uttered by a certain person). Even reputable sources can be mistaken about the facts. But it could be that you're warranted in believing what reputable sources tell you, even though those sources can be mistaken. Still, this shouldn't be mistaken for fact-making.
Here's a rough characterization of what makes something a fact. It's not going to satisfy everyone, but it is a decent place to start. First note that we can use sentences to say things about the world - for instance that certain objects stand in certain relations to each other, as when I say "the chair is to the left of the table." According to a popular theory of truth, the statement "the chair is to the left of the table" is true just when the chair is actually to the left of the table. So that statement is false when the chair is to the right of the table, or on top of the table, or whatever. Basically a statement is true when it correctly describes how the world is (again, very roughly). Facts are what we get when our statements are true.