Logic and Superman

Lois Lane is journalist. She believes that a Clark Kent will investigate a news story with her.
So the sentence

(1) Lois Lane believes that Clark Kent will investigate a news story with her.

is true

But

(2) Clark Kent = Superman

So the sentence

(3) Lois Lane believes that Superman will investigate a news story with her.

should also be true (because very little is changed, only Clark Kent who is also a Superman is referred to by a different sound)

But (3) is false, because Louis Lane does not know that Superman is Clark Kent

Why do I mention this thrilling, old logical puzzle. See next entry.



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