Here are three examples of recent, epistemic definitions of 'fact':
First, there's this definition in a psychological dictionary:
Fact: An actual occurrence or state of affairs, empirically established and usually consensually validated, distinguished from fictive, confabulated events. The latter may be held as opinion, belief, or theory. (Raymond J. Corsini, The Dictionary of Psychology [Philadelphia, PA: Brunner Mazel, 1999], p. 362)Next, there is the definition that Justin McBrayer quoted in his contribution to the New York Times (March 2, 2015), according to which something can be a fact only if it 'can be tested or proven' (McBrayer, 'Why Our Children Don’t Think There Are Moral Facts', New York Times [March 2, 2015]).
Finally, I obtained (from a source in California) this image of teaching material for a Grade 6 class:
'Fact' is here defined in terms of a consensus among the relevant experts. In this case, the definition requires that a fact be believed (or agreed to) by qualified scientists but doesn't strictly entail that this agreement on the facts should rise to the level of knowledge. Still, given the context, agreement among qualified scientists seems to be what grounds knowledge. (I'll leave aside the difficulties in the conceptions of theory and law in this image.)
I'm baffled by these epistemic conceptions of fact. Surely, it makes perfectly good sense to say, 'We don't know all the facts,' where 'we' refers to all of humanity. That is, there remain facts about our world no one yet knows. But if we adopted an epistemic definition of fact, then any such expression of epistemic humility would involve a self-contradiction; for, given an epistemic definition, the statement that 'Humanity does not yet know all the facts' would be equivalent to saying, 'Humanity does not yet know all the known facts.'
Or consider this uncontroversial expression of epistemic humility: there are facts that no one yet knows. Given the first definition that I quoted, this claim would be equivalent to saying, 'There are empirically established (and therefore known) facts that no one yet knows.' On the second definition, it would be equivalent to saying, 'There are facts that can be tested and proven (and that are therefore known) that no one yet knows.' On the California definition, it would be the same as saying, 'There are things currently agreed on by qualified scientists (and thus known) that no one yet knows.'
Not only do these epistemic definitions render a perfectly sensible claim self-contradictory, but they are inimical to the continued progress of science; for they nullify a primary reason for continuing to pursue scientific investigation. There would be little need, if any, to pursue science if humanity were already in possession of all the facts about the world. The continued pursuit of science presupposes that we don't know all the facts. It assumes that there remain facts about our world and its workings that continue to elude us -- all of us (even the qualified scientists).