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

Date: Mon, 6 Jun 2005 14:35:54 +0200

Le 06-juin-05, à 01:40, Brent Meeker a écrit :

*> What do you take to be the standard definition of "knows"? Is it "X
*

*> knows Y"
*

*> iff "X believes Y is true" and "Y is true"?
*

That's the one by Theaetetus.

*> Or do you include Gettier's
*

*> amendment, "X knows Y" iff "X believes Y is true" and "Y is true" and
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*> "There is
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*> a causal chain between the fact that makes Y true and X's belief that
*

*> Y"?
*

It could depend of the axiom chosen to describe belief.

For knowability I take the S4 axioms and rules:

1) axioms:

<all classical tautologies>

BX -> X

BX -> BBX

B(X->Y) -> (BX -> BY)

2) Rule:

X X -> Y X

----------- ----- (Modus ponens, necessitation)

Y BX

But in the interview of the Lobian machine I recover the S4 axioms +

Grz, from

defining "knowing X" by "proving X formally and X true" (I apply the

Theaetetus on

formal provability).

I cannot use Gettier's given that I have no notion of causality to

start with. (Recall

I don't have any physical notion to start with).

Bruno

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

Received on Mon Jun 06 2005 - 08:36:57 PDT

Date: Mon, 6 Jun 2005 14:35:54 +0200

Le 06-juin-05, à 01:40, Brent Meeker a écrit :

That's the one by Theaetetus.

It could depend of the axiom chosen to describe belief.

For knowability I take the S4 axioms and rules:

1) axioms:

<all classical tautologies>

BX -> X

BX -> BBX

B(X->Y) -> (BX -> BY)

2) Rule:

X X -> Y X

----------- ----- (Modus ponens, necessitation)

Y BX

But in the interview of the Lobian machine I recover the S4 axioms +

Grz, from

defining "knowing X" by "proving X formally and X true" (I apply the

Theaetetus on

formal provability).

I cannot use Gettier's given that I have no notion of causality to

start with. (Recall

I don't have any physical notion to start with).

Bruno

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

Received on Mon Jun 06 2005 - 08:36:57 PDT

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