We don't need to though. Through good investigative work, people have figured out the answers. Personally, my favourite documentaries on the international banking cartels are the following:
The very first one I saw was in animated format, but don't let its flash graphics and humour fool you, it's good stuff:
Money As Debt - Full Length Documentary - YouTube
It has a Part II and III as well, but the first one was my favourite.
I later saw a documentary it mentioned. It's rather long, but it gets into the historical battle between those who recognize the thievery of our current banking system and those who like things the way they are now:
The Money Masters - YouTube
Finally, I found this one:
The American Dream Film-Full Length - YouTube
It's also a flash type presentation, and certainly has its humour, but I see nothing wrong with some humour when trying to get difficult messages across.