If it's an assertion, we can test it. "The sky is blue" is an interpretation that can be re-tested. "My car has a flat" can be tested. If it's something that happened, we can't repeat history, so we're left digging up falsifiable evidence. This is the work of detectives when they solve cases, or historians re-evaluating historic facts. You don't re-test blood you no longer have, you're only able to scrutinize the analysis. You don't test again for genocide, you seek documents, records of communication, money trails, etc.

A super casual modern day example would be an assertion like "Joe must be gay". You never know until you ask him, and that is if he's honest with you. But everyday-life is full of gross approximations based on bias and partial information.

But the key, even in Joe's case, is you have to go back to the real source. If all we can do is talk about Joe, we can never know for sure. Much like celebrities we are so certain are gay, but haven't come out openly yet. So as long as computers can't leave their data centers, there really isn't any amount of data that can prove anything to them. They can't experience the truth, because ultimately the truth rests on experience and experience of evidence.