PHIL 101 DAY 3Epistemology Day 2

Maymester 2007

The Traditional Definition of Knowledge

Knowledge is:

Justified True BeliefWhen I believe that P

P is true

And I have the proper kind of reason to believe P (a Justification),

Then, I Know P

Skepticism

Despite the fact that we ordinarily claim to have knowledge. Many people deny that knowledge is possible.

The people are called “SKEPTICS”

This is a key issue in Descartes Mediation I (see link on schedule)

Skepticism (1)

• Skepticism is the belief that knowledge is not possible, either in general or for some specific area or subject matter

• Why would anyone deny the possibility of knowledge?

(Is this just a wacky problem that philosophers have?)

Skepticism (2)

Classical Skepticism:

Usually starts from disagreement or difference…

A gap between appearance and reality

Different perceptions of the same object

Examples for Classical Skepticism

1. Sea Water –Poisonous to man, healthy for fish

2. Is the water hot? (after being in the cold, after being in the sun?)

3. Is 5’ 11” Larry Tall? Next to 6’ 4” Sam? Next to 4’ 3” Jerry?

4. Is the table flat? – how fine grained do you want to be?

Skepticism (3)

• Skepticism about Justification

More modern forms of skepticism generally take the form of an attack on the possibility that a belief or beliefs can be justified

Skepticism (4)

Justification Skepticisma) Assumes a theory of justificationb) Shows how common knowledge/beliefs

will fail to be justified on that theory

Can be Global or Local

Universal Belief Falsifiers are Possible

Skepticism (5)

• Descartes (Hyperbolic Doubt)(Reading: Http://www.earlymoderntexts.com/pdfbits/dm1.pdf )

Principle of Hyperbolic Doubt

“If I can doubt B, then I will assume that B is false”

Yields certain knowledge. But knowledge is hard or impossible to get!

An Ideal Knowledge test:

Possible Beliefs

TEST

Of all possible beliefs only those we know get called knowledge

The Hyperbolic Doubt Test

All Possible Beliefs

Doubt Test

Beliefs it is possible to doubt

Beliefs you cannot doubt

Hyperbolic Doubt: Pro vs. Con

PRO

1. Ensures certain knowledge

2. Eliminates all false beliefs

3. Test is easy to perform

CON

1. Limits knowledge to certain truths

2. May eliminate some truths

3. Test is too demanding

Does HYPERBOLIC DOUBT draw the line too narrowly?

How does Cartesian Skepticim work?

• The key moves all involve finding some basis upon which to doubt a belief or certain kinds of beliefs.

Useful analogy: The Matrix movies

“ARE YOU IN THE MATRIX RIGHT

NOW?”

Skepticism (6)Descartes’ Main Arguments:

• Fallibility of the senses

- Objects from a distance

- Jaundice

• The Argument from Dreams/Illusions

• The Power of God - needs to be supplemented

• The Evil Demon

Skepticism (7)

• Responses to Cartesian Skepticism

1) Accept Global Skepticism

2) Accept Hyperbolic Doubt and Look for Indubitable Knowledge (e.g. the Cogito)

3) Change our conception of justification.(Is Hyperbolic doubt our standard of justification?)

Transition:If we give up Hyperbolic Doubt we risk the possibility

that false beliefs might get treated as knowledge.

Can we give up Hyperbolic Doubt unless we have an alternative test in mind?

What test should we use?

(…Partially Depends on what kinds of knowledge we accept)

2 Types of Knowledge

• A Priori – Knowledge which does not require experience

• A Posteriori – Knowledge that requires experience

Ask:

1) Is there really an A Priori Knowledge?

2) Is there anything that cannot be known by experience alone?

A Priori Knowledge?

Here are some types of knowledge that people have claimed require a priori knowledge

• Mathematical Truths• Concept of God• Concept of Infinity• Concept of Immortality• Linguistic Meanings

Empiricism

Many people think that knowledge is rooted in sense experience

How much can we know by means of our senses?

READ: Empiricism Section in Rauhut

HUME: Enquiry Sections 1-5, esp. 2-3

(http://www.earlymoderntexts.com/pdfbits/he1.pdf)

Empiricism (2)

Definition of Empiricism:

Empiricism is the view that our knowledge of the world is obtained primarily through our senses.

Historically, this view is closely associated with the three British Empiricists:

• John Locke• Bishop Berkley• David Hume

Empiricism 3

What can we discover with our senses?

1. Basic sensory information (sense data)

2. If we have memory, then we can also discover which experiences are common or uncommon, which tend to go together, and which tend to precede or follow others.

Empiricism 4

David Hume

We will focus on the last of the British Empiricists, David Hume.

According to Hume, the basic unit of empirical information is the IMPRESSION

Empiricism 5Hume’s Picture of “The Understanding”

ALL PERCEPTIONS

IDEAS

IMPRESSIONS

most vivid

Strongest

Copies of Impressions

Less Vivid

Influenced by thought and memory

Empiricism 6

“Nothing in the Mind that was not first in the senses”

Every perception (thought) is either a) an Impression b) b) an idea.

Experience is complex, but we can abstract simple impressions from it.

Empiricism 7

ABSTRACTION is the power of the understanding that allows us to pull out the experience of RED from the impression of the Apple.

IMAGINATION allows us to combine simple ideas into complex ideas

Empiricism 8

Once an impression is perceived it is immediately experienced, but if we reflect upon the impression or make it an object of thought, it becomes an idea.

We have many ideas but they have only a few relations

Empiricism 9Relations of Ideas

Resemblance (Is the experience similar to another?)

Contiguity (Does the experience tend to come with another experience?)

Cause and Effect (Conjunction-Does one experience always come after another)

Empiricism 10

HUME’S FORK

Hume allows that we can know:

a) Matters of fact ( Complex immediate experiences – impressions)

b) Relations of Ideas (How our ideas are related)

The LIMITS of Humean Empiricism (1)

We can have knowledge according to HUME, but it is limited.

Hume’s theory of justification is roughly this:

You are justified in believing that P just in case your belief that P resulted from an immediate impression or reflection upon the relations of ideas.

The LIMITS of Humean Empiricism (2)

We cannot know:

1) That we are identical with ourselves in the past

2) That one event causes another (needs explanation)

3) That God exists

4) That the future will be like the past.(Problem of induction – uniformity of nature assumption)

5) Cannot know laws of nature

Hume the Skeptic?

Ironically, Hume purchases knowledge at the price of forcing us to become skeptics about many things

One option: Berkeley’s Idealism (Esse est Percipi)

Solisipsm

Mathematical Truths, Infinity, etc.

Earlier I suggested that Empiricists need to tell a story about these concepts:

Here it is: All of these are complex relations of ideas created by means of imagination

e.g. Limit + negation = Infinity

Is this story good enough?