Hello!

I love thinking about concepts like fact, truth, belief, their differences... you can go down some great philosophical rabbit holes. We'll keep it short here, though! To simplify down what you're saying: "why should I believe anything since knowledge evolves over time?"

There is no such thing as an unbiased human. We all are born and raised within societies that instil in us certain beliefs, ideals, and paradigms about the world. There will never be an entirely "objective" history written because no such thing exists, and that's fine! What historians are trained to do is to see those influences, as best as we can, and to account for them in our writings to paint as accurate a picture as possible. Of course, as you pointed out, society changes over time-- and that's fine too! I believe the contention in your question comes from the idea that knowledge is binary: either you're wrong or your right. In reality, our understanding of the world around us is far more like an organism that's constantly evolving: sometimes we may mutate and go down a wrong turn (i.e. eugenics), but on the whole we learn from our past; not just our past history, but past historians! Knowing how Herodotus thought about the world is incredibly valuable for us to understand the time he lived in, and his ideas about the world around him. The fact that we've grown our knowledge base as a species in the two-thousand years since doesn't invalidate his understanding of the world. Same with Carlyle: "Great Man Theory" is 'discredited' in the sense that it's not a theory that modern historians apply (conciously, at least) to their subjects; however, that doesn't mean we've blotted it from history, or that it provides us with no value. Carlyle was quite influential on the popular conception of my field (French Rev!) but that doesn't mean I have to draw a line and say he's either totally right, or totally wrong.

To bring us, then, to modern historians: why should you believe anyone over past writers, if we could be proven wrong in the future? I would say this is a bit of a logical fallacy; for example, would you apply that same question to science? It goes back to knowledge being an evolving, growing, living thing: it will grow, and mutate, and change over time, which is absolutely expected and a great thing! It does not mean then that there are two extremes: absolute "truth" (which I would argue philosophically doesn't exist) or absolute disbelief: "nothing can be known absolutely, so my only reality is my own existence." But finding the middle ground between these two extremes is a worthy cause! If this is something you're interested in, I highly suggest The Art of Thinking by Vincent Ruggerio. It's an excellent book in logic that teaches you how to critically examine and evaluate your own thoughts and biases and those of others. Regardless, here is how I would summarize: a fact can be thought of as a piece of knowledge that has sufficient proof behind it, and a consensus of those trained to understand that proof. Science is where we're more familiar with this: if a physicist tells me that they discovered a Higgs-Boson in that massive collider... thing.... I may not take them as an individual at their word; however, if the scientific community in general agrees with their finding, then excellent! I'm on board. That constitutes our *current* extent of knowledge. We may tweak it as further experiments are done, but that's how knowledge grows. It's quite similar in history: when I post a comment, it's peer-reviewed by the mods and fellow flaired users, in the sense that if I said the French Revolution was started because Louis XVI was secretly in league with a metal company to make money off of guillotine blades, it would be removed pretty quickly for lack of proof. I am fully aware that our understanding of the French Revolution will continue to evolve, but that doesn't mean I should throw up my hands and decide since nothing is knowable, I'll go drink arsenic because who knows, maybe in the future people will recognize it's benefits as a health tonic.

This is such a great topic, and I could go on for a lot longer, but I hope I haven't lost you already. I appreciate where you're coming from with this question, and hope my answer at least provided another perspective from someone being trained in the fine art of history. Have a good one!