Masked Man Fallacy

The Masked Man Fallacy — also called the intensional fallacy — occurs when someone assumes that because they know something under one description, they must know it under all descriptions. The classic example: you know your father, but you don't know the masked man at the party. The masked man is your father. Therefore you simultaneously know and don't know the same person — the fallacy arises from confusing knowledge of a thing with knowledge of all its descriptions. In business, this manifests when leaders assume that understanding one dimension of a person, product, or market means they understand it entirely. You know your customer as a buyer, but you don't know them as a user. You know your employee as a performer, but you don't know them as a leader. The fallacy produces false confidence — the certainty that you understand something fully when you've only seen one of its masks.