Concerning scientific facts, you're touching on something for which there seem to be two primary philosophies. One is that an observation is a fact. The other is than an observation is tentative and that our confidence in an observation only grows as others replicate the observation with the same result.
The objection to the latter view is that it trivializes discussion by forcing us to give up the very convenient word "fact", and most discussions get by pretty well using the word "fact" for anything not contentious.
An aside: I think evolutionists could get by quite well without insisting that the occurrence of macroevolution is a fact.
--Percy