Who said "But it isn't, so it ain't. That's logic"?

This quote is attributed to Tweedledee and Tweedledum.

But it isn't, so it ain't. That's logic - Tweedledee and Tweedledum

"But it isn't, so it ain't. That's logic"

Tweedledee and Tweedledum

Character in Through the Looking-Glass

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"We call it a Bread-and-Butterfly."

"If it was so, it might be; and if it were so, it would be; but as it isn't, it ain't. That's logic."

"Contrariwise, if it was so, it might be."

"We must have a bit of a fight, but I don't care about going on long."