Bruno Marchal wrote:
>Let us suppose the native is knave. Then what he said was false. But he
>said "if I am a knight then >Santa Claus exists". That proposition can only
>be false in the case he is a knight and Santa Claus >does not exists.
This only works if you assume his "if-then" statement was shorthand for the
"logical conditional", ->, in formal logic (see
http://en.wikipedia.org/wiki/Logical_conditional )...if you interpret it
some other way, like that it was shorthand for a modal logic idea like "in
every possible world where it is true that I am a knight, it is true that
Santa Claus exists", I don't think it can only be false if he is a knight.
For example, there might be a possible world where he is a knight and Santa
Claus does *not* exist, in which case the statement "in every possible world
where it is true that I am a knight, it is true that Santa Claus exists" is
false.
I think this is why the problem is confusing--for me, possible-world
statements more accurately capture the meaning of "if-then" statements in
ordinary language than the logical conditional.
Jesse
Received on Fri Jul 23 2004 - 15:55:00 PDT