When someone is not playing with a full deck, he is either mentally, psychologically or intellectually deficient. The deck referenced in not playing with a full deck is a deck of cards. There is a popular story that the origin of this phrase dates back to the 1500s, when a tax was levied against decks of cards. People would get around the tax by purchasing decks of 51 cards instead of 52 cards, thereby not playing with a full deck. This is a false story originally circulated in a viral email purporting to solve the murky origins of certain idioms. Not playing with a full deck is one of many phrases that emerged in the United States during the 1980s to describe someone “missing something upstairs”. Similar phrases are not firing on all cylinders, two bricks shy of a load, and half a bubble off plumb.
“If she heard you were talking about her as the short woman not playing with a full deck, chances are you weren’t going to work there the next day,” he said. (The Sacramento Bee)
“Anyone who hears about an approaching World’s Fair and says, ‘Hey, that’s the perfect time for me to open a boarding house and rent out [rooms] to women I can kidnap, torture, and kill,’ is not playing with a full deck of cards.” (The Guardian)
This has helped me understand that we all must constantly forgive each other, because like I said before, we’re not playing with a full deck. (The Daily Herald)
She concluded by saying, “If Republicans think they’re going to win this election by demeaning or dividing women, then they’re the ones not playing with a full deck.” (The Wall Street Journal)