On 09 Feb 2011, at 20:29, Brent Meeker wrote:
<snip>
On 2/9/2011 8:02 AM, Bruno Marchal wrote:
I define then knowledge, following Theaetetus by the true opinion
(Bp & p),
You've never said what your answer is to Gettier's example.
I did it, the saturday 29 Jan 2011, according to my computer. Let
me paste it again. It is probably too short. I have a full chapter
on this in "Conscience et Mécanisme". Tell me if you see the point,
or if I should make it clearer:
quote:
Apes fetus can
dream climbing trees but they do that with ancestors climbing the
most
probable trees of their most probable neighborhoods since a long
period.
With classical mechanism, I would say, that to know is to believe
p when
"luckily" p is true,
> So what is your response to Gettier's problem? [Brent Meeker]
The answer is that, with comp, we cannot distinguish reality from
dream. We can know that we are dreaming (sometimes), but we cannot
ever know for sure in a public way that we are awaken.
Another fact related to this is that knowledge, consciousness and
truth are not machine-definable. If we are machine, we can use
those notion in theoretical context only.
In practice, as real life illustrates very often, we never know as
such that we know. We belief we know, until we know better.
The SAGrz logics is a logical tour de force. Here Gödel's theorem
gives sense to Theaetetus. S4Grz, the logic of (Bp & p) formalizes
a notion which is not even nameable by the machine, unless she
postulates comp and relies explicitly on that postulate, or
better, relies on the study of a simpler than herself machine.
In science, or in public, we never know, as such. Knowing is a
pure first person notion. But this does not mean that we cannot
make 3-theory on such pure first person notion, as S4Grz
illustrates particularly well. Same remarks for feelings (Bp & Dt
& p).
Bruno
http://iridia.ulb.ac.be/~marchal/
Hmmm? I guess I thought you hadn't answered because I don't grasp
the relevance of your answer. Gettier points out that one can
believe a true statement for reasons that have nothing to do with
what makes the statement true.
It is a very old argument. It is usually presented with "dreams". In
"Conscience et mécanisme" (C&M), I give this version: a person is
asleep in a flying plane, and dreams that he is flying. The
Theaetetical definition of knowledge forces us to say that he knows
that he is flying, despite the wrong reason.
The answer is that this is an intrinsic defect of the notion of
knowledge, and unless you believe that you can distinguish "I am
awaken" from dreaming, there is no means to ever develop a notion of
knowledge not having that problem. So the critics of the Theatetical
definition of knowledge is based on the (admittedly strong feeling)
that we can know that we are not dreaming. But I show that both comp,
and experimental neurophysiology entails the existence of "contralucid
dreams" (as I define them in C&M). Some drugs can also lead to
contralucidity, apparently.
In his example Bob buys a new car which is blue, but while waiting
for the car to be delivered he borrows a car which also happens to
be blue. Jim sees Bob driving this car and believes that Bob has
bought a new car which is blue. It is a true belief, but only by
accident. So it seems that there is a difference between true
belief and knowledge.
It seems, only.
Gettier proposes that the true belief must be causally connected to
the fact that makes it true in order to count as knowledge.
If such causal connection exist, then comp has to be false.
The analogy in arithmetic would be to believe something, like
Goldbach's conjecture, which may be true but is unprovable.
I guess you mean: might be unprovable. OK.
To sum up: those, like Gettier, who criticizes the true-belief as
knowledge, does believe in a magical (non Turing emulable) connection
between mind and some reality. My point is that such connection is
incompatible with comp, and is hard to sustain with the idea of
dreams, perfect video-game, and many things made possible in the comp
theory.
There is always a part of serendipity in the knowing phenomenon, if
comp is correct. The only thing which can be known and known as such
is consciousness here and now. All the rest are beliefs, well or badly
justified, and sometimes true, but we can never be sure on them. It is
almost obvious if you realize that with comp, knowledge in a
constructed mental state.
Bruno
http://iridia.ulb.ac.be/~marchal/
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