Read: The Analysis of Knowledge
THREE KINDS OF KNOWLEDGE
A. Knowledge by acquaintance(Ex1) Plato knew Socrates
(Ex2) Stefan knows Fred Feldman.
(Ex3) Bob Dole knows Bill Clinton.B. Knowledge how (knowledge as a skill or ability)
(Ex1) She knows how to ride a horse.
(Ex2) John knows how to drive a car.C. Knowledge that (propositional knowledge)
(Ex1) He knows that it is a cold Winter day.
(Ex2) She knows that every mother is female.
TRADITIONAL ANALYSIS OF PROPOSITIONAL KNOWLEDGE (KNOWLEDGE AS JUSTIFIED TRUE BELIEF)
JTB (A Traditional Analysis of Knowledge)A person knows that a proposition (or statement) is true if and only if 1) this person believes that this proposition is true; 2) this proposition is in fact true; and 3) this proposition is justified for this person (that is, this person has adequate evidence or warrant for believing that this proposition is true).S knows p if and only if
1) S believes that p;
2) p is true; and
3) S is justified in believing p.(Ex 1) Stefan knows that he was born in Warsaw.
Stefan believes that he was born in Warsaw, he was in fact born in Warsaw, and he is justified in believing so.(Ex 2) Mary knows that she has a sister.
Mary believes that she has a sister, she in fact has a sister, and she is justified in believing so.(~Ex3) Stefan believes that the number of people in this class is even and this belief is true.
Stefan does not know it if he lacks justification. This is merely a lucky guess.(~Ex4) Mark believes that his car is park in front of a mall, and he is justified.
Mark does not know it, if this belief is false (e.g. the car has just been stolen).(~Ex5) Susan has strong evidence that people like her, and it's true that they like her.
She does not know, if she does not form a belief that people like her.
SOME ALLEGED SOURCES OF PROPOSITIONAL KNOWLEDGE
Memory
Testimony of others
Inference
Sense Perception
Inner Sense
Pure Reason
THE EPISTEMIC PRIMACY OF SENSE PERCEPTION
If anyone has propositional knowledge of contingent facts about the external world from any source, then someone has propositional knowledge of contingent facts about the external world by sense perception.
TRADITIONAL SKEPTICISM ABOUT EXTERNAL WORLD
A. A skeptic grants that we know the laws of logic, analytical and conceptual truths, etc.B. She also grants that one knows the current content of one's consciousness (that is, one knows what one senses, feels, perceives, desires, wants, etc.).
C. The skeptic denies, that one knows that there are things to which these feelings, perceptions, beliefs, etc. correspond.
THE THESIS OF THE EXTERNAL WORLD SKEPTIC
"p is a perceptual belief" =def. "p is a belief about the existence or characteristics of the objects external to mind".(Ex1) The table has four legs.
(Ex2) There is a black car parked in front of my house.
(~Ex3) I feel hot, tired, and nervous.
(~Ex4) It seems to me that the table has four legs.EWS No one ever knows any perceptual belief.
That is, the skeptic denies that anyone ever knows any perceptual belief.
(2) THE NAIVE THEORY OF PERCEPTUAL KNOWLEDGE
Read: Sextus Empiricus, The Modes of Suspension of Judgment; Descartes, Meditation One
THE NAIVE ASSUMPTION (NA)
Ideas of material objects are caused by the objects they represent and they accurately represent those objects.
THE NAIVE THEORY (NT)
A person has direct perceptual knowledge that a material object, O, has some sensory quality, F, if and only if
1. she knows that she has an idea representing O having F;
2. based on this idea, she forms a belief that O exists and has F; and
3. NA is true.
SOME ARGUMENTS AGAINST THE NAIVE THEORY (NT)
The Bath House Argument
1) Sextus' idea of the vestibule represents it as warn, but Quintus' idea of the vestibule represents it as cold.
2) If (1), then someone has an idea that does not accurately represent its cause.
3) If someone has an idea that does not accurately represent its cause, then (NA) is false.
4) If (NA) is false, then the Naive Theory is false.
_____________
5) Therefore, the Naive Theory is False. [From (1)-(4)]The Pig in the Mire Argument
1) The pig's idea of the mire is sweet-smelling, but the person's idea of the mire is stinking.
2) If (1), then someone has an idea that does not accurately represent its cause.
3) If someone has an idea that does not accurately represent its cause, then (NA) is false.
4) If (NA) is false, then the Naive Theory is false.
_____________
5) Therefore, the Naive Theory is False. [From (1)-(4)]
Read: Locke, Essay Concerning Human Understanding; Berkeley, Principles of Human Knowledge
JOHN LOCKE
|
1632 |
born in Wrington, Somerset, England |
|
1652 |
Went to Oxford University (1656 -- got a B.A.) |
|
1664 |
Taught moral philosophy at Oxford. |
|
1667 |
Moved in with Earl of Shaftesbury as a personal physician. |
|
1689 |
Published "First Letter on Toleration", Essay Concerning Human Understanding, and two Treatises of Government. |
|
1704 |
Died while being read the Psalms. |
LOCKE'S THEORY OF PERCEPTUAL KNOWLEDGE
The ideas of primary qualities of bodies are resemblances of them, and their patterns do really exist in the bodies themselves, but the ideas produced in us by these secondary qualities have no resemblance of them at all... There is nothing like our ideas [of secondary qualities] existing in the bodies themselves. They are only a power to produce those sensations in us: what is sweet, blue, or warm in idea, is but the certain bulk, figure, and motion of the insensible parts... (p. 156)
PRIMARY VS. SECONDARY QUALITIES
Primary (or Original) Qualities: extension, figure, motion and rest, number, and position.
Ideas caused by primary qualities accurately represent those qualities.Secondary (or Imputed or Sensible) Qualities: looks, smells, tastes, sounds, feels, etc.
Secondary qualities are powers (or dispositions) in bodies caused by the primary qualities of the bodies.
Ideas caused by secondary qualities do not accurately represent those qualities.
LOCKE'S ASSUMPTION AND THEORY OF PERCEPTUAL KNOWLEDGE
(LA ) Ideas of material objects are caused by those objects and accurately represent those objects with respect to their primary qualities.(LT) A person has direct perceptual knowledge that a material object, O, has some sensory quality, F, if and only if
0) F is a primary quality; and
1) she knows (by inner sense) that she has an idea representing O having F;
2) based on this idea, she forms a belief that O exists and has F; and
3) LA is true.
|
1685 |
born in in Kilkenny, Ireland. |
|
1700 |
Entered Trinity College, Dublin. |
|
1709 |
An Essay Towards A New Theory of Vision |
|
1720 |
A Treatise Concerning The Principles of Human Knowledge. |
|
1728-1731 |
Trip to America. Lived in Newport, R.I. |
|
1734 |
Became Bishop of Cloyne in Ireland. |
|
1753 |
Died in Oxford |
ARGUMENTS AGAINST LOCKE'S THEORY
An Argument From Paragraphs 14 and 15
1) The truck appears large to a nearby observer, but small
to a distant observer.
2) If (1), then at least one observer has an idea that does not
accurately represent the truck's extension (that is, one of truck's
primary qualities is misrepresented).
3) If at least one observer has an idea that does not accurately
represent the truck's extension, then both Locke's Assumption and
Locke's Theory of Perception are false.
___________
4) Therefore, Locke's Assumption, and his Theory of Perception are
false. [from (1)-(3)]
An Argument From Paragraph 18
1) We can't know LA by inner sense.
2) We can't know LA by pure reason.
3) If (1) and (2), then we can't know LA.
____________
4) Therefore, we can't know LA. [from (1), (2) & (3)]
5) If we can't know LA, then Locke's Theory of Perception is
false.
____________
6) Therefore, Locke's Theory of Perception is false. [from (4)
& (5)]
BERKELEY'S ARGUMENT AGAINST MATERIALISM
The Three in the Quad (Paragraphs 22 & 23)
1) It's impossible to conceive of an object existing
unperceived.
2) If (1), then all objects depend on perception.
3) If all objects depend on perception, then there are no
material objects.
__________
4) Therefore, there are no material objects. [from (1), (2),
and (3)]
Thomas Reid, Of the Existence of a Material World [H]; Keith Lehrer, Reid Thomas (from the Cambridge Dictionary of Philosophy) [H]
THOMAS REID (1710 - 1796)
|
1710 |
born near Aberdeen, Scotland |
|
1726 |
Graduate from Marishal College, Aberdeen |
|
1737 |
A pastoral charge at New Machar [studies Berkeley's A Treatise Concerning The Principles of Human Knowledge (1720); and Hume's Treatise of Human Nature (1739)] |
|
1751 |
Regent at King's College, Aberdeen |
|
1764 |
An Inquiry into the Human Mind on the Principles of Common Sense |
|
1764 |
Professor of Moral Philosophy, Glasgow |
|
1785 |
Essays on the Intellectual Powers of Man |
|
1788 |
Essays on the Active Powers of Man |
KEITH LEHRER ABOUT REID: "When Chisholm was a department chairperson at Brown he received a telephone call from a man saying that he was a busy man but had time to read one serious book in philosophy and wanted to do so. He said that he was not interested in entertainment but simply wanted to read a book with a greater amount of truth than any alternative. Chisholm, wishing to reflect on the matter, said the man should call back the next day, and he would give him his advice. The next day Chisholm recommended that the caller study Reid. It was a sound judgment." [Thomas Reid (1989)]
REID'S DIAGNOSIS
[Philosophy put forth by Berkeley and Hume] "pretends to
demonstrate, a priori, that there can be no such thing as a material
world; that sun, moon, stars, and earth, vegetables and animal
bodies, are, and can be nothing else, but sensations in the mind, or
the images of those sensations in the memory and imagination; that,
like pain and joy, they can have no existence when they are not
thought of... [Common sense] can conceive no otherwise of
this opinion, that as a kind of metaphysical lunacy, and concludes
that too much learning is apt to make men mad; and that the man who
seriously entertains this belief [that there are no material
things]... surely has a soft place in his understanding, and has
been hurt by much thinking. [Reid, Inquiry...]
The belief of a material world is older, and of more authority, than any principles of philosophy.
FIRST PRINCIPLES
All reasoning must be from first principles; and for first
principles no other reason can be given but this, that, by the
constitution of our nature, we are under necessity of assenting to
them... reason can neither make nor destroy them; nor can it do
anything without them... (p. 209)
A mathematician cannot prove the truth of his axioms, nor can he prove anything, unless he takes them for granted. We cannot prove the existence of our minds, nor even of our thoughts and sensations.
That our thoughts and sensations must have a subject, which we call our-self, is not therefore an opinion got by reasoning, but a natural principle. That our sensations of touch indicate something external, extended, figured, hard of soft, is not a deduction of reason, but a natural principle. (pp. 209-210)
AN ASSUMPTION ABOUT PERCEPTION
(AAP) Ideas of material objects are caused by the objects they represent and they give us defeasible reasons for thinking that those objects have qualities (properties, features) represented by those ideas.
A THEORY
(TAP) A person has perceptual knowledge that a material object, O, has some sensory quality, F, if and only if
1. she knows (by inner sense, introspection) that she has an idea representing O having F;
2. based on this idea, she forms a belief that O exists and has F;
3. her belief is true; and
4. AAP is true.
TWO KINDS OF CERTAINTY
Practical Certainty: A belief (proposition, statement), P, is practically certain for someone if this person has evidence which makes P very plausible for this person.
Absolute Certainty: A belief (proposition, statement), P, is absolutely certain for someone if this person has evidence which excludes a possibility that P is false (i.e., that S is mistaken about P.
Practical certainty may be enough in so far as the ordinary affairs of life are at stake. However, some philosophers (notably Descartes) think absolute certainty is required when we engage in philosophical search after truth.
TRADITIONAL ANALYSIS OF KNOWLEDGE REVISITED
A Skeptical Interpretation of JTB Analysis: A person knows that a proposition (or statement) is true if and only if
1. this person believes that this proposition is true;
2. this proposition is in fact true;
3. this proposition is absolutely certain for this person.An Anti-Skeptical interpretation of JTB theory: A person knows that a proposition (or statement) is true if and only if
1. this person believes that this proposition is true;
2. this proposition is in fact true;
3. this proposition is practically certain for this person.; and
4. ??? [the condition to take care of Gettier's and Gettier-like cases].KNOWLEDGE AND SKEPTICISM--REVIEW
1. Three sorts of knowledge
- knowledge by acquaintance
- knowledge as a skill, and propositional knowledge
- how to recognize what kind of knowledge is attributed to a person by a given statement.
2. The analysis of the traditional concept of knowledge:
- Three conditions which are necessary (i.e. which must be satisfied) for someone to know something; and allegedly sufficient for the traditional analysis.
- Possible objections to this analysis (including Gettier-like objections).
3. The notion of perceptual belief, examples of perceptual and non-perceptual beliefs.
4. External World Skepticism:
- what is granted by a skeptic; why?
- What is skeptical hypothesis?
- That is, what does the skeptic deny; why?
- Which necessary condition for knowing is never satisfied according to the skeptic? ]
How does the skeptic argue for the skeptical claim?
5. Naive Theory of Perception: Naive Assumption; Sextus' objections to this assumption.
6. Locke's Theory of Perception:
- Locke's empiricism
- his distinction between primary and secondary qualities
- Locke's assumption.
7.Berkeley's criticisms of Locke:
- Berkeley's and Descartes' skeptical arguments; do they work against Locke?
- Radical skeptical hypotheses.
8. Berkeley's reply to the skeptic: does it work; why? His arguments against materialism.
9. Thomas Reid's defense of common sense. his views about "First Principles"
10. Knowledge as defeasibly justified true belief. Does this concept of knowledge help to refute skeptic? (Knowledge with practical certainty and with absolute certainty.)
You will be allowed to use one sheet of notes.
Readings: