Or, "I can't verify my information."
"I don't need to prove that, because it's common knowledge.""That's not worth questioning, because it's common knowledge."
"I don't need to verify that statistic, because it's common knowledge."
I've run across this concept in debates a few times recently - the idea that claiming "common knowledge" is as reliable for informational purposes as citing a specific study or reputable source of information.
No. It really isn't. Here's why:
"Common knowledge" is that you eat 8 spiders in your sleep each year, right?
"Common knowledge" is that the British have horrible teeth, right?
Need a bit more?
"Common knowledge" is that domestic violence and sexual assault are "gendered" crimes.
"Common knowledge" used to be that black people were "less human" than white people and therefore slavery wasn't really a human rights violation.
"Common knowledge" used to be that women couldn't do math, fix a car, or shoot a gun.
Shouldn't we challenge the veracity of "common knowledge" when cited as if it's a reliable source?