The fact that new information exists about the past in general means that we have an incomplete road map about history. There is a necessarily fallibility … if you will.
In The Black Sawn, Nassim Taleb writes:
History is useful for the thrill of knowing the past, and for the narrative (indeed), provided it remains a harmless narrative. One should learn under severe caution. History is certainly not a place to theorize or derive general knowledge, nor is it meant to help in the future, without some caution. We can get negative confirmation from history, which is invaluable, but we get plenty of illusions of knowledge along with it.
While I don't entirely hold Taleb's view, I think it's worth reflecting on. As a friend put it to me recently, “when people are looking into the rear view mirror of the past, they can take facts and like a string of pearls draw lines of causal relationships that facilitate their argument while ignoring disconfirming facts that detract from their central argument or point of view.”
Taleb advises us to adopt the empirical skeptic approach of Menodotus which was to “know history without theorizing from it,” and to not draw any large theoretical or scientific claims.
We can learn from history but our desire for causality can easily lead us down a dangerous rabbit hole when new facts come to light disavowing what we held to be true. In trying to reduce the cognitive dissonance, our confirmation bias leads us to reinterpret past events in a way that fits our current beliefs.
History is not stagnant — we only know what we know currently and what we do know is subject to change. The accepted beliefs about how events played out may change in light of new information and then the new accepted beliefs may change over time as well.