I believe the best way to answer this question is to propose a small discussion about "Historical Logic" as established by Edward Thompson in the book "Poverty of Theory - or an Orrery of Errors". In general, that great English historian proposes that the Historical Knowledge is made by a logical method of enquiry that is appropriate to historical materials. To that logical method, he calls "Historical Logic". That logic consists in a dialogue between concept (or the theory of historical analysis, any of the many available to the historian) and the evidence (or the facts, the historical facts). In that way, the historical knowledge has as object the evidences, the facts, that certainly have a real existence. And here is the catch: they're only knowable through vigilant historical procedures - procedures that are part of that dialogue between theory and evidence. In its nature, historical knowledge is provisional and incomplete, selective and limited, and defined by the questions proposed to and by the evidence, but not therefore untrue (that I believe is the core of your question). As Thompson explains: "The object of historical knowledge is 'real' history whose evidence must necessarily be incomplete and imperfect. To suppose that a 'present', by moving into a 'past', thereby changes its ontological status is to misunderstand both the past and the present. The palpable reality of our own (already passing) present can in no way be changed because it is, already, becoming past for posterity. To be sure, posterity cannot interrogate it in all the same ways; to be sure, you and I, as experiencing instants and actors within our present, will survive only as certain evidences of our acts or thoughts. While historians may take a decision to select from this evidence (...), the real object remains unitary". Sorry for the long quote, but in resume it explains quite well the nature of the historical knowledge. Given that the facts (or evidences) are real because the once were part of a present, as our very present is real, the historian can utilize the theories of historical logic in order to access those facts. The selection of the theory will be determined by the facts and vice versa, in a constant dialogue between theory and facts. That's the way real historical knowledge is made, and the very dialogue, made by countless historians over the years, serves as positive proof of history. Finally, to which fact its most adequate theory. As we established, the evidence will determine which theory, method, is best to analyze it. Written texts, letters, works of art, painting, material culture, coins, interviews, tweets, reddit responses on r/ask askhistorians, you name it. If it's based on historical logic, it has no "resolution", you only need the right theory, method to the evidence you are working with. Sorry for the long answer. I hope I have helped in your doubts about that matter and apologies for my bad English, as I'm a Social History post-graduate student from Brazil.