Re: Observer-Moment Measure from Universe Measure

From: Bruno Marchal <>
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
> "There is
> 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
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).

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

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