if only...
An understanding of history, and indeed of current affairs, comes largely from an informed analysis of conflicting information.
The convenience of a smoking gun with a complete set of clear fingerprints may never materialize, but unless you're willing to sit on your hands and hope the universe doesn't club you over the back of the head, you're forced to make decisions based on what you've got.
If you haven't read Peggy Noonan's article, it's well worth a few minutes (thanks for the link, Tom).