It’s a paradox If he can come in he can come in if he can’t come in he can, But he can’t come in unless she says he can come in and she said he can come in conditionally if he in fact can come in.

To put it another way:

Condition 1: Entry is permitted on the grounds that Entry is permitted.

Condition 2: Entry is permitted on the ground Entry is permitted.

In Python:

define Entry(permission):
   if Entry(permission) == True:
      permission = True
   else:
      permission = False
Entry(False)