Epistemology “Episteme” = knowledge “Logos” = words / study of What does it mean to know something? How do we know things?

Plato’s Cave

Theories of Knowledge

Epistemology “Episteme” = knowledge “Logos” = words What does it mean to know something? How do we know things?

Divisions of Theories of Knowledge

Rationalists Those who believed that all knowledge can be known by the mind inquiring within itself We are born with innate ideas Rene Descartes 1596-1650

Empiricists Those who believe that all knowledge is derived from experience John Locke (1632-1704) George Berkeley (1685-1753) David Hume (1711-1776)

Rene Descartes (1596-1650)

All knowledge can be known through the mind inquiring within itself Rationalist All knowledge can be known through the mind inquiring within itself

Cartesian Theory of Knowledge Meditation One “The Method of Doubt”

In order to discover that which is absolutely true, we try to find that which we absolutely cannot doubt

we must disregard that path to absolute truth If we get deceived once, we must disregard that path to absolute truth

Can we absolutely trust Our Senses? Sight Hearing Touch Taste Smell

NO!

Sight? Mirage

Ringing in our ears after concert Hearing? Ringing in our ears after concert

Touch? Amputation

Taste? Novocain

Smell? Hallucinations

Sometimes they are incorrect Our Beliefs? No! Sometimes they are incorrect

Certain we have bodies? NO! Matrix!

Can you tell that you are dreaming when you are dreaming? Dreams? Can you tell that you are dreaming when you are dreaming?

You usually realize you have been dreaming AFTER You wake up

How do you know for certain that your life is not simply a dream And when you die You simply wake up from this dream

An Evil God? Is there anything this Evil God could not deceive you into thinking you were doing?

Waterskiing

Mountain Climbing

Could this Evil God deceiving you into thinking if you weren’t really thinking?

Wouldn’t you have to be thinking in order to be deceived?

“I think, therefore I am” Cogito Ergo Sum “I think, therefore I am”

Our Essence Is Thinking

When we think about ourselves thinking, we cannot be deceived Can’t be deceived When we think about ourselves thinking, we cannot be deceived Even by an Evil God

This is the only thing we can know for absolutely certain Cogito Ergo Sum

Solipsism the view that the self is all that can be known to exist.

Criterion of Certainty Clear and Distinct Idea We have a clear and distinct idea of something it is true Cogito ergo sum Material Objects and Extension

Standard Formal (1) I think Therefore (2) I am (I exist) Cogito ergo sum

Standard Formal (1) I can’t be sure about my beliefs (2) I can’t be sure about my senses (3) I can’t be sure about my thoughts (4) But when I think about myself thinking, I must exist Therefore (5) I exist

Doesn’t get us very much Problem Doesn’t get us very much

In order to get to objective reality, he must prove two other things

1. That God Exists

2. That God is not a Deceiver

Descartes’ Proof for the Existence of God Where does the idea of God come from?

Our idea of God is greater than we should be able to think of

God is: Perfect Infinite Omnipotent Omniscient Omni-benevolent Eternal

Nothing is our world possesses these qualities

Descartes’ Conclusion The origin of our idea of God is God

That God is not a Deceiver Deception is an imperfection God is perfect Therefore God is not a deceiver

Reality can be trusted most of the time What does this give us? Reality can be trusted most of the time No 100% But most If we are careful

4 Rules that will help us to arrive at approximate truth Discourse on Method 4 Rules that will help us to arrive at approximate truth Make less mistakes

1. Never accept anything as true unless it is self-evident

Divide each problem into as many parts as possible 2. Divide and Conquer Divide each problem into as many parts as possible

Then more to the more difficult 3. Begin with the Easiest Then more to the more difficult

4. Be as Complete as Possible Omit nothing

Innate Ideas Ideas we are born with

1. God’s Existence

2. Metaphysical Truths The Law of Non-Contradiction Something cannot both exist and not exist at the same time

3. Mathematical Truths 1 + 1 = 2