On the Ownership of Knowledge

At what point can you say that you know something? 

Maybe that seems like a weird question...as you might have noticed, I'm a student. This means, like most students I spend a lot of time writing papers.  Long research essays, book reviews, short reflection papers, the length and the subject are pretty irrelevent in that almost always the same thought comes up.  Inevitably there will be something I want to say, maybe a comment about a certain figure's life or beliefs, or a comparison of one historical event to another.  But as I go to type it, I start to worry...the thought "how do I know this?" crosses my mind. "Did I read this somewhere?  Is this someone else's idea that I only think is my own? Or am I safe to assume it would be accepted that I just knew it?"  With the ever present fear of an accusation of plagiarism I start to worry that I cannot speak in an authoritative voice of my own.  I begin to look for other sources who have said something similar so that I can quote them, taking refuge behind the words of another. 

I understand the argument that while I'm an undergrad it is assumed I am an authority on nothing.  I need to at least have a master's before I can begin to have the audacity to speak directly without the shield of protective quotes.  But sometimes it just seems so ridiculous, when as essay begins to look like one long string of quotations from other sources, and my contributions amount to "It is said that, [quotation] which would suggest as so-and-so said [quotation]".  Okay, granted I am exaggerating somewhat for effect, but I think you get what I mean. 

Can we assume that we know things that are a matter of public record and historical fact?  For instance, the dates of World War 2?  1939-1945, as most people are probably aware.  Certainly you could open any one of hundreds of books on the war and find those dates in them.  Are those dates intellectual property of someone else?  Or is it fair to say that I know them?  What about events that occurred during my lifetime?  If I lived through it, am I allowed to comment on it without referencing someone else?  You see how you can start to chase your own tail around and around over this. 

I know that plagiarism is a constant concern, especially with the ever present internet to steal ideas from, and goodness knows I wouldn't want my hard work and ideas ripped off and attributed to someone else...but sometimes I just get frustrated by how careful I have to be to avoid even the slightest possibility of a hint of unattributed thought in anything I submit. 

Sigh.