Re: ... cosmology? KNIGHT & KNAVE

From: Jan Harms <jan.harms.domain.name.hidden>
Date: Fri, 23 Jul 2004 16:15:20 +0200

> (problem 4)
> You get a native, and asks her ........if Santa Claus exists.
> The native answers this: "If I am a knight then Santa Claus exists"
> What can you deduce about the native, and about Santa Claus?

Lets give a name to the sentence:
S="If I am a knight then Santa Claus exists"

1. If the native is a knight, then S is true. If S is true and the native is
a knight, then Santa Claus exists. Therefore, Santa Claus exists.

2. If the native is a knave, then S is false. If S is false (1->0), then the
native must be a knight. So he can't be a knave. So a knave could never say S and be consistent.

Conclusion: The native is a knight and Santa Claus exists.

Jan
Received on Fri Jul 23 2004 - 11:41:34 PDT