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).



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