>>19726364 pb
"can't prove a lie"
means you can't prove a truth by means of a lie.
sorry I wasn't clear.
someone;s lie can't be proven as true.
that's what it means.
One can prove that someone's lied; for instance,
(from the example given, and) the people (Jew Hater shills) can be proved to lie who claim "it's the Jews" behind every tree, every mailbox and every crime.
That's an easy proof, but the lying shill will never admit it.