Saying a lie a 1000 times does not make it true.
Just as 1000 people saying the lie also does not make it true.
And then there's this ...
Liar Paradox
"The first sentence in this essay is a lie.
There is something odd about saying so, as has been known since ancient times. To see why, remember that all lies are untrue. Is the first sentence true? If it is, then it is a lie, and so it is not true. Conversely, suppose that it is not true.
..."
An interesting read, from: https://plato.stanford.edu/entries/liar-paradox/




