I'm currently reading my way through the novellas on this year's Hugos shortlist and I've just finished Ken Liu's The Man Who Ended History: A Documentary, a fictional contemplation of the horrors of Unit 731. Using the conceit of form of time travel that allows an watch an historical event at the cost of never being able to view the event again, the story considers how past guilt can embarrass and colour the present, and how matters of interpretation and epistemology can spill over and cause real emotional harm to the people involved.
I mention all this as a prelude to quoting one of the principal characters on the subject of history, narrative, truth and morality:
[I]t is not true that just because all narratives are constructed, that they are equally far from the truth. The Earth is neither a perfect sphere nor a flat disk, but the model of the sphere is much closer to the truth. Similarly, there are some narratives that are closer to the truth than others, and we must always try to tell a story that comes as close to the truth as is humanly possible.
The fact that we can never have complete, perfect knowledge does not absolve us of the moral duty to judge and to take a stand against evil.
Not an original sentiment, but nicely expressed nonetheless...