“Masked man” (fallacy)

Alternative name for the „intensional fallacy“. The name is referring to a logical paradox, first formulated by the Greek philosopher Eubulides of Miletus (4^th century BCE):

You see a man wearing a mask.
Because of the mask, you do not realize that it is your father.
That is, you do not know who the masked man is;
At the same time, you know who your father is.
Therefore, you both know the masked man and yet do not know him at the same time.

In this story, the terms “masked man” and “your father” refer to the same person (i.e. they have the same extension), but they reference it in two different ways, thus leading to a paradox.

For more information, please see: Intensional fallacy.

• Masked-man fallacy on Wikipedia
• The Masked Man Fallacy on Fallacy Files