The Old Man

When you see something that the government or an elected official proclaims as true, how do you know that it is not? Look, I get the old joke about their lips move, but more seriously, how do you know that they are not telling you the  truth? For example, if the history books told you that Abe Lincoln "freed" the slaves, or that George Washington was just a slaver, or that Thomas Jefferson was a misogynist and a racist, how would know that it was or was not true? What about things more recent? What if the history books told you that the Vietnam War was just American Imperialism? Or that Richard Nixon was pure evil? That Ronald Reagan was an Alzheimer's riddled occupant of the White House? How would you KNOW that it was untrue, or at least not the full story? A generation from  now, how will your children or grandchildren KNOW that what you believe today wasn't wrong?