Jennifer Cook O’Toole, "The Asperkid’s (Secret) Book of Social Rules"
(Jessica Kingsley Publications, 2012) page 137
Eager to share some juicy gossip, the man asked if Socrates would like to know the story he’d just heard about a friend of theirs. Socrates replied that before the man spoke, he needed to pass the “Triple-Filter” test.
The first filter, he explained, is Truth. “Have you made absolutely sure that what you are about to say is true?” The man shook his head. “No, I actually just heard about it, and …”
Socrates cut him off. “You don’t know for certain that it is true, then. Is what you want to say something good or kind?” Again, the man shook his head. “No! Actually, just the opposite. You see …”
Socrates lifted his hand to stop the man speaking. “So you are not certain that what you want to say is true, and it isn’t good or kind. One filter still remains, though, so you may yet still tell me. That is Usefulness or Necessity. Is this information useful or necessary to me?” A little defeated, the man replied, “No, not really.”
“Well, then,” Socrates said, turning on his heel. “If what you want to say is neither true, nor good or kind, nor useful or necessary, please don’t say anything at all.”
Note that any of the three conditions is enough of a reason to share it.