Download - What is Knowledge? Do We Have Any Knowledge?
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Introduction to Philosophy
WHAT IS
KNOWLEDGE? (AND DO WE HAVE ANY?)
Professor Duncan Pritchard FRSE [email protected]
www.ppls.ed.ac.uk/people/view/duncan-pritchard-frse
Ren Descartes (1596-1650)
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Structure of the Lecture
Part One: What is Knowledge? Part Two: Do We Have any Knowledge?
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Part One:
What is Knowledge?
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Propositional versus Ability Knowledge
Knowledge-that: Knowing that Paris is the
capital of France. Knowing that the earth
orbits the sun. Knowing that one has
toothache.
Knowledge-how: Knowing how to drive. Knowing how to play
piano. Knowing how to beat the
stock market.
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Two Conditions for Propositional Knowledge
One can know a proposition only if: (i) That proposition is true;
(ii) One believes that proposition.
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Knowing versus Getting it Right
Two Intuitions About Knowledge
The Ability Intuition
Knowledge requires getting it right through
ones ability
The Anti-Luck Intuition
Knowledge requires getting it right in a non-
lucky way
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The Classical Account of Knowledge
One can know a proposition if, only if: (i) That proposition is true;
(ii) One believes that proposition; (iii) Ones belief is justified.
Plato (427-347 BC)
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Gettier Counterexamples
Examples of justified true belief where the true belief in question is just too
lucky to count as knowledge
Edmund Gettier (b. 1927)
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A Gettier-Style Case
The Stopped Clock
You believe that the time is 7.28am. You are justified in believing that the
time is 7.28am. It is true that it is 7.28am.
But you dont know that its 7.28am because, unbeknownst to you, what you are looking at is a stopped clock. A stopped clock, yesterday.
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Another Gettier-Style Case
The Sheep
You believe that there is a sheep in the field. You are justified in believing that there is a sheep in the field.
It is true that there is a sheep in the field. But you dont know that there is a sheep in the field because,
unbeknownst to you, what you are looking at is a big sheep-shaped rock which is obscuring from view a sheep hidden behind.
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A Formula for Inventing Gettier-Style Cases
Step One Take a belief that is formed in such a way that it would usually result in a false belief, but which is
justified nonetheless.
Step Two Make the belief true, albeit for reasons that have
nothing to do with the subjects justification.
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Patching up the Classical Account:No False Lemmas
One can know a proposition if, only if: (i) That proposition is true;
(ii) One believes that proposition; (iii) Ones belief is justified;
(iv) Ones belief is not based on any false assumptions (or lemmas).
Keith Lehrer (b. 1936)
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Two Questions Raised by Gettier-Style Cases
(1) Is justification even necessary for knowledge?
(2) How does one go about eliminating knowledge-undermining luck?
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Part One Conclusions
Knowledge is not justified true belief. Nor is knowledge justified true belief plus
some obvious extra condition. So what is knowledge?
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Part Two
Do We Have any Knowledge?
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Radical Scepticism Radical scepticism is the view that
knowledge (at least of the world around us) is impossible.
Sceptics make use of sceptical hypotheses, scenarios where
everything is as it usually appears to be, but where we are being radically
deceived.
The sceptic says that we cannot rule-out sceptical hypotheses, and thus argues that we are unable to know anything about
the world around us.
Ren Descartes (1596-1650)
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The Brain-in-a-Vat Sceptical
Argument
1. I dont know that Im not a brain-in-a-vat.
2. If I dont know that Im not a brain-in-a-vat, then I dont know very much.
C. So, I dont know very much.
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Brains-in-Vats
Question: Why dont we know that were not brains-in-vats? Answer: Because we cant tell the difference!
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Brains-in-Vats and Everyday Knowledge
So even if we dont know that were not brains-in-vats, so what?
But if you were a brain-in-a-vat, then you wouldnt have hands (since brains-in-vats are handless by
definition). So how do you know that you have hands?(And if you dont know this, what do you know?)
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Epistemic Vertigo
It is certainly part of the human condition that we are fallible
creatures. But perhaps, once we reflect on the matter (and thus reflectively ascend), we realise
that there is more than just fallibility at issue here. Maybe we simply dont know as much as we
typically suppose.
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Part Two Conclusions
Radical scepticism is the view that we know very little, if anything, about the world around us.
Radical scepticism makes use of sceptical hypotheses, which are scenarios indistinguishable from ordinary life but where we are radically in error.
It seems that if we cannot rule-out these hypotheses, then much of what we think we know is under threat.
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Further Reading
I explore these issues about the nature and
extent of knowledge in my introductory textbook, What is This Thing Called Knowledge? (Routledge).
See especially parts 1 & 3.
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Thank You For Listening!
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