Why do people talk about history like it's cut and dry?

Question

When people talk about history they usually have a thought out (somewhat, sometimes) specific opinion on how and what exactly happened. Occasionally people don’t even acknowledge where the information they are referencing came from. Like they had the epiphany themselves.
I look at history as if, for example, 2 people I know have an argument or disagreement outside of my presence. The fact that the argument happened is the only thing that can be relied on. For the most part people aren’t honest enough to tell the whole truth or admit their own guilt, so both sides of the story is frankly ‘he said, she said’. You tend to form your own opinion on a consensus, but you never truly know what the FACTS are.
So the question is, how can people talk about history like they have no doubt that it occurred the way it’s been written in the history books?

Answer 1

RIGHT ON I agree with this on sooooo many levels
and to answer because people are mindless sheep that have No Idea on how to question so they just BELIEVE whatever someone says

Answer 2

There are reasons to believe and reasons to disbelieve. Check the facts as they are presented from other sources. Look at the outcome. Can you find proof that it happened the way it was written. Can you find proof that it didn't happen as written. If you have a specific example, search it from every angle and lean most heavily on reports of the people that were there.