I'm trying to find a story from the 40s or 50s, where a futuristic device was delivered to the protagonist's apartment (by a tech from the future).
The protagonist tries to figure out the device, and eventually figures out that it's a sort of mind control device, designed to ensure that every citizen only has "approved" thoughts.
I had thought it was "The Twonky", but the copies online don't match my recollections.
Specifically, it had the idea that "It doesn't matter what people think, as long as they all think the same."
"The Twonky" doesn't have this idea in it.
I believe that it was written by William Tenn, but I'm not at all sure.