“You’re not a doctor!”
This is a fallacy of dismissing an argument by saying that the person making it isn’t qualified to make it. That could be valid. A layperson giving detailed medical advice. Then again, if a person studied the subject for decades but didn’t technically have a medical degree (but knows more than a doctor) then is it a fallacy to take their (medical) argument seriously?
It could manifest as refusing to take good advice or consider an argument because “you’re not a psychologist, how can you give dating advice?”
Whenever you hear or think, “well what do THEY know? What do *I* know?” then this fallacy is in play.
YOU ARE VALID
WE’RE ALL EXPERTS HERE
DISCOUNT NOONE