I’m talking about in regards to events having happened. I’m an archivist and work in collections, so I approach through that way. Some things are debated upon to have happened. Recent news article in my town claims that a notable historical figure walked through a park in town. If we have a picture or video of said figure in said park, then the evidence is undeniable. Now let’s add the bias: we have video evidence that a bomb went off in one place, then the video could be used to argue that bombing is bad because of X, Y, Z that is all demonstrated within the video. For the park example, the fact that said historical figure visited the park could be used as an argument why the park needs more funding, which is an argument that the park employees and board members would argue. History is not biased, the people who write about it are. History is either true or false, what is said based on said history is the bias. However, historians go beyond this and argue their own ideas based on said history. The idea that history is only true or false is to prevent ideas like determinism (that events in history were “fated” to happen, which to us in the communist circle is being against metaphysics) which is the historian’s enemy. In another post I was talking about the hypocrisies of a lot of western academia historians, and being deterministic is why. They make history biased because they don’t look at it objectively. They look at history as “how can I make money off of this?” Instead of looking at it as reporting the truth or not.

Edit: added more things to make my argument more clear