Here's one of the sorts of examples that
Gettier used in his paper.

Suppose you believe Brad, a student
from your online class, owns a porche.
Brad has provided ample evidence at
www.bradsporche.com (occurring at the
end of every one of his messages) which
feature pictures of him standing next to
the car, washing it, buffing it, sititng
behind the wheel, etc. He has even
scanned the title and sales contract,
along with a copy of his late Uncle
Eddie's Will, where he got the $75,000 to
buy it.

You have a justified belief that Brad owns
a Porche. On the basis of this belief, you
form the more general belief "Someone
in my Philosophy 202 on-line class owns
a porche."

However, suppose Brad is a fraud. His
low self-esteem drove him to make this
website so he'd have something to
impress people with. As a matter of fact,
Brad is poor and works at a carwash. His
buddies at the carwash took the pictures
and the scanned documents are clever
forgeries.

But, to complicate matters, another
student, Cecil, DOES own a porche. He
never tells anyone about it because he
feels guilty about being so rich. As a
matter of fact, the reason why he's at LCC
and not Harvard is his rejection of his
family's money and priveledge--all except
his prized porche, which he couldn't bear
to part with.

Now let's consider the belief "Someone
in PHL 202 Online owns a porche". It it
true? Yes, because Cecil owns a
Porsche? Is it justified? Yes, because
even though you don't know about Cecil,
Brad's website is a convincing hoax. Is it
KNOWLEDGE? Gettier says that intuitive,
NO, it is NOT knowledge. So, here's an
example of a true, justified belief which
isn't knowledge.

The problem lies in the fact that the truth
of the belief and the justification don't
hook up in the right way. Your justification
was based on a false belief about Brad
and you didn't even know about Cecil. It's
really just an accident that Cecil happens
to be in the class, making what would
otherwise be a false belief, true. Most
philosophers think that this is a technical
objection and that the definition can be
patched up by adding some further
stipulations about how the truth and the
justification of the belief are related to one
another.

Prof. Borrowdale.