- Contemporary messages sorted: [ by date ] [ by thread ] [ by subject ] [ by author ] [ by messages with attachments ]

From: Bruno Marchal <marchal.domain.name.hidden>

Date: Fri, 23 Jul 2004 22:20:15 +0200

All right. But modal logic are (traditionaly) extension of classical

logic, so that causal implication, or natural language entailment,

when study mathematically are generally defined through

modalities + "material implication".

So in a sense, you confuse yourself by premature anticipation.

I know the "material" implication needs some time to be familiarized with.

Bruno

At 15:45 23/07/04 -0400, Jesse Mazer wrote:

*>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
*

*>
*

http://iridia.ulb.ac.be/~marchal/

Received on Fri Jul 23 2004 - 16:18:27 PDT

Date: Fri, 23 Jul 2004 22:20:15 +0200

All right. But modal logic are (traditionaly) extension of classical

logic, so that causal implication, or natural language entailment,

when study mathematically are generally defined through

modalities + "material implication".

So in a sense, you confuse yourself by premature anticipation.

I know the "material" implication needs some time to be familiarized with.

Bruno

At 15:45 23/07/04 -0400, Jesse Mazer wrote:

http://iridia.ulb.ac.be/~marchal/

Received on Fri Jul 23 2004 - 16:18:27 PDT

*
This archive was generated by hypermail 2.3.0
: Fri Feb 16 2018 - 13:20:09 PST
*