Ok, we could know about some large-scale events where there were lots of witnesses that something happened, maybe even mostly what happened, but I don't see how

Ok, we could know about some large-scale events where there were lots of witnesses that something happened, maybe even mostly what happened, but I don't see how we could know who was ultimately responsible or why. Secret agencies can pin blame on anyone or any country they like, and there's ultimately no way to tell.. especially when double agents, false flag operations, and provocateurs are taken in to account. The intelligence field is the proverbial hall of mirrors, and that a spy agency said something or was in any way involved is my cue to give up any hope of ever figuring out what was really going on.