Might be good to look at barn-fancying websites at this point…
Non-inferential versus inferential knowledge
What is knowledge 2016 revison no false lemmas condition
Internalism vs. Externalism
• Internalism - justification is solely
determined by factors that are internal to a
– Q. – ‘What counts as external to a person?’
• Externalism - the internal justification
condition is replaced by an external
knowledge-generating factor. It depends
on additional factors that are external to a
• Devised unusual counter-examples to the JTB
– JTB = iff X has a justified true belief that p, X thereby
knows that p
– Gettier cases = cases in which I have justified true
belief, but claim to knowledge seems peculiar
– ‘cases of lucky true beliefs show that the justification
condition should be either strengthened, added to or
– JTB is proven to be necessary but not sufficient, so
• Either additional condition needed
• or J needs revision somehow
Responses to Gettier
1. add a ‘no false lemmas’ condition (J+T+B+N)
2. strengthen the justification condition:
infallibilism and the requirement for an
impossibility of doubt (Descartes)
3. replace ‘justified’ with ‘reliably formed’ (R+T+B)
4. replace ‘justified’ with an account of epistemic
• To infer = to work one
thing out from another
• A successful argument
is made of a sequence
of linking steps or
• God exists
• And God isn’t a
• So I can trust my
senses (when they are
checked by my intellect)
• They tell me the
external world exists.
• And so the external
world does exist!
Adding an additional condition:
‘No false lemmas or premises’
• A premise is a starting point in an argument or
• A lemma = a subsidiary or intermediate theorem
in an argument or proof
• Gettier problems: here, conclusion is based on
mistaken intermediate theorem, although
conclusion is correct.
• So: ruling out false lemmas would rule out
‘No False Lemmas’ in Standard Form
S knows that P iff
1. 1. S believes that p
2. S is justified in believing p.
3. P is true.
4. S‘s justification is not based on a false premise
S did not infer P from a false lemma
Clark, M., 1963. “Knowledge and Grounds. A Comment on Mr.
Gettier's Paper,” Analysis, 24: 46–48. (also - Armstrong, D. M.,
1973. Belief, Truth, and Knowledge, C.U.P.)
False Lemmas in more detail
• Gettier gets us to agree that
1) ‘…it is possible for a person to be justified in believing a
proposition that is in fact false. ‘
2) ‘for any proposition P, if S is justified in believing P, and P entails
Q, and S deduces Q from P…then S is justified in believing Q.’
• The false lemma in Gettier’s argument
‘P: Jones is the man who will get the job, and Jones has ten coins in
his pocket. Proposition P entails Q: The man who will get the job
has ten coins in his pocket.’
• Here, P is false, although Q is true.
• So ruling out false lemmas would rule out Gettier’s
Why might these images be relevant to
what has just been discussed?
Problems with the
‘No False Lemmas’ condition
• The extra condition deals with cases where S infers that P
based on a false lemma.
• But some knowledge = perceptually direct or non-inferential
– Put another way: you believe what you perceive – you don’t have to infer
what it is that you are perceiving (‘I need a wee’…)
– And if perceptually-based knowledge-claims were rephrased inferentially,
no false lemmas would be involved. (‘It appears to be a duck. I normally
trust my senses. So it is a duck’)
• Which means that Gettier counter-examples can be devised
where you don’t make an inference (so there are no false
lemmas)…yet you still don’t have knowledge.
• Alvin Goldman’s 1975 article ‘Discrimination and Perceptual
Knowledge’ gives the famous ‘Barn County’ example.
The Barn County Example
(Alvin Goldman, 1976)
‘Henry is driving in the country-side with his son. For the boy's
edification Henry identifies various objects on the landscape as
they come into view. "That's a cow…that's a tractor…that's a
silo, that's a barn," etc. Henry has no doubt about the identity of
these objects; in particular, he has no doubt that the last-
mentioned object is a barn, which indeed it is. […] Suppose we
are told that, unknown to Henry, the district he has just entered
is full of papier-mâché facsimiles of barns. […] if the object on
that site were a facsimile, Henry would mistake it for a barn.
Given this new information, we would be strongly inclined to
withdraw the claim that Henry knows the object is a barn. How is
this change in our assessment to be explained?’
What’s the difference between example 1 and 2?
(1) Roderick is pretty clever
(2) Even clever students must
study for hard tests.
(3) But he doesn’t have much
time to study because of
(4) So we can predict that he
won’t do well.
(5) It follows thus he will feel
This is not Roderick
The ‘Barn County’ example, explained
• Remember: Henry is excellent at identifying barns non-
– So if he identifies something as a barn, he knows.
– Yet he’s driving through a strange county where there are many fake barns, and
some real ones.
– So if Henry saw one of the fake ones, he would mistake it for a barn.
– And hence even if Henry actually were to see a real barn, we would not say
that he knows that what he sees is a barn (because he would not be able to
reliably tell which was which, real or fake).
• So our view of whether Henry knows that what he sees is a
real barn has changed.
• ..even though Henry has justified true belief that is not
inferred from any false lemmas.
• So we can immediately conclude: the ‘No False Lemmas’
condition is shown by Barn County to be inadequate…
• Revisit your Gettier counter-example.
• Consider your No False Lemmas
• Does it still stand, or is the knowledge-
claim based on non-inferential knowledge?