Re: Gettier Problems

From: George Greene (greeneg_at_cs.unc.edu)
Date: 10/22/04 

Date: 22 Oct 2004 12:30:06 -0700

mmortalist" <Reanimater_2000@yahoo.com> wrote in message
news:<h76dnWyOTa3qC-3cRVn-hw@comcast.com>...
> 1. Suppose you're driving through rural Pennsylvania. As a matter of fact,
the
> region you're driving through contains a lot of fake barns:
etc.
> 2. You have a justified belief that someone in your office owns a Ford.

As Barb Knox et al already pointed out, no, especially if there
are a finite number of people in your office, you DON'T have such
a belief. The objects of propositional attitudes are intensional.

> And as it happens it's true that someone in your office owns a Ford.
> However, your evidence for your belief all concerns Nogot,

Believing that Nogot owns a Ford is NOT the same as believing that
"someone" owns a Ford. The fact that Nogot's owning a Ford ENTAILS
that "someone" owns a Ford is NOT relevant. Belief-sets do not
have to be consistent, or complete. If you know P, and P->Q, but
you don't KNOW that P->Q, then you may not know Q. That objection
doesn't apply directly here since you DO know that Nogot's owning
a Ford DOES entail that someone owns a Ford, but that is not the point:
the point IS that your answer to "would you still believe that someone
owned a Ford if you found out that Nogot did not own a Ford?" is NO,
not yes and not "I don't know". CONTEXT, i.e., what OTHER facts you
already know and what new information you can accommodate without
concluding that you are being deceived (or presented with inconsistent
data) MATTERS.

> who as it turns out owns no Ford. Your belief
> that someone in the office owns a Ford is true because someone
> else in the office owns a Ford.

Not exactly. That "someone" owns a Ford is NOT what you believe,
in any case. You actually believe that Nogot owns a Ford.
What this implies about your other beliefs is complicated, not
simple.

> Call this guy Haveit. Since all your evidence concerns Nogot and not
> Haveit, it seems, intuitively, that you don't know that someone in your
office
> owns a Ford. So you don't know, even though you have a justified belief that
> someone owns a Ford, and, as it turns out, this belief happens to be true.
>
> 3. You're in the meadow, and you see a rock which looks to you like a sheep.
etc.

I bitterly resent your attempt to present this as 5 different cases.
All that is actually going on here is that there is a level on which
disjunctions are simply not knowable. You are simply trying to allege
that because, for all P and Q, P -> PvQ, -- and everybody knows this --
believing P must entail believing PvQ, and having a justification for
believing P must entail having a justification for believing PvQ.
Well, it doesn't, not necessarily. Some kinds of new information
are assimilable. The point is simply that P and PvQ are different,
in a way that MATTERS, as objects of propositional attitudes.

> 4. Jill reads in the newspaper that the president of her country has been
> assassinated. In fact, this story is true. However, the president's
associates
> have mounted a campaign to suppress the story, and they've been broadcasting
> false reports on all the television stations that the president is OK, the
> assassin actually only killed a bodyguard.
etc.
It either is or isn't part of Jill's past experience that TV and newspaper
reports contradict each other. CONTEXT MATTERS.

> 5. You see Tom Grabit hide a book underneath his jacket...
> On the basis of this, you form the justified belief that Tom stole a
> library book. As it happens, your belief is true. However, unbeknownst to
you,
> Tom's mother was going around today telling people that Tom was thousands of
> miles away, and that Tom's evil twin John was visiting...
etc.
Tom either has a twin or he doesn't. Upon being presented with
evidence that he did, you would either believe it or you wouldn't.
Without knowing this CONTEXT, it is impossible to determine how
you would or wouldn't revise relevant justifications. In every context
in which you might actually operate, how new information would affect it
is already known. But you are not presenting any of that context in
any of these examples.

All of your examples come down to somebody being justified
in believing P, and therefore justified in believing PvQ, while
P is false and Q is true. This is not 5 different phenomena that can
arise in 5 different ways. It is 1 phenomenon and you ought to just
go back and instantiate/identify P and Q in all 5 of your examples.
There is a sort of violation of duality (between conjunction and
disjunction) at work here: If you know P&Q then you know P & you know Q.
But does knowing PvQ entail that 1) you know P, OR 2) you know Q?
As all these examples show, having a justified true belief that PvQ does
NOT entail having a justified true belief that P, OR having a justified
true belief that Q, if justification operates in the naive way

Relevant Pages

  • Re: Gettier Problems
    ... > barn instead, you would have believed that it was a barn. ... You have a justified belief that someone in your office owns a Ford. ... that would defeat your justification for believing that someone ...
    (sci.logic)
  • Re: Gettier Problems
    ... >> that someone owns a Ford. ... >> Learning of the mother's claim doesn't defeat your justification because ... > The sun rose yesterday ... All knowledge is gained through induction. ...
    (sci.logic)
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