This might be a dumb question but I was just wondering: When historians found or find written texts of ancient, (extinguished), societies, in whatever form (carved in stone, written on paper or parchment, you name it) how can they distinguish if the text tells an actual fact or is just a fictional but realistic sounding story some guy made up?
Example: Let’s imagine some historian finds a text that he dates back to the ancient Greeks and the text is about a philosophical debate between two famous philosophers. How can historians be sure that the debate written in the text actually happened and is not some fictional scenario someone wrote down?
There are ways of cross-checking things. Literary sources are only part of the picture; other pieces of evidence (material stuff like coins, seals, that sort of thing) can help untangle the story. In fact, I'm now reading through Parvaneh Pourshariati's Decline and Fall of the Sasanian Empire: The Sasanian-Parthian Confederacy and the Arab Conquest of Iran, and the bit I'm now at uses a collection of seals to help disentangle a certain debate in Sasanian history. Beyond that, the historical method already takes into account such problems with its very nature. Of course, more can always be said, so if anyone would like to speak further on how historians deal with texts, please go ahead!
For the meantime, as this question has arisen before, I commend to your attention the following posts: