Most of what you think you know is bullshit. Not to single you out or anything; most of what we all know is complete bullshit. How would you know if it wasn't? After all, most of everything you know is predicated upon the trust of other people knowing their shit.
Do you actually know that Germany lost WWII? How do you know that we nuked Japan? How do you know that we won WWII? How do you know that the Periodic Table of Elements isn't some grand scam?
A What I am trying to say is that you really only know what you've been told, and that you trust that knowledge. Misplaced trust can be a very bad thing, indeed.