Receptionist: I'm sorry Dr. Crane, you're not on the list, I can't let you in.
Frasier: But I have an invitation.
Receptionist: Yes, but you're not on the list.
Frasier: Yes, but I do have an invitation.
Receptionist: But you aren't on the list.
Frasier: Yes, well, if I were on the list, I wouldn't need an invitation, I'd just say "I'm on the list." Therefore, the invitation supersedes the list.
Receptionist: No, invitations are given out only to those on the list.
Frasier: Ah-ha. But you do concede that I do have a valid invitation?
Receptionist: Yes.
Frasier: Then it naturally follows that I would be on the list.
Receptionist: But you're not.
Frasier: Then how did I get the invitation?
Receptionist: I really don't know. You could have stolen it...
Frasier: Are you accusing me of deception?