Bad example: "unobservable" and "we were looking the other way" are not the same thing. Have you scanned the young man's brain activity as you interrogate him?

Bad example: "unobservable" and "we were looking the other way" are not the same thing. Have you scanned the young man's brain activity as you interrogate him? Have you done that with all future technology? By the way, any chances the young man can write? Here's a tricky one: did I ate spaghetti three years ago? You don't know and very probably you'll never know, but it's an empirical question nonetheless, and who knows, maybe tomorrow you'll think of a way to actually find out, or you'll stumble on some evidence you didn't know was there.