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
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/
