Have you heard the one about Mitt Romney at the "Ask Mitt Anything" event? It seems that someone asked him how many counties Massachusetts has. Mitt said "thirteen." An aide corrected him and said "ten." The actual answer is fourteen.
It's true that this displays less ignorance than one might imagine since county-level government in the Bay State is fairly insignificant. The weird thing, though, is that Romney for some reason felt he couldn't admit that he didn't know. Presidents are bound to face topics they don't know anything about (nobody could be knowledgeable about every issue that crosses the Oval Office) and need to respond to ignorance in appropriate ways.
Matthew Yglesias is a former writer and editor at The Atlantic.