Epistemologists: 2 schools of thought.

 

1. Rationalists
 

·         Trust in a priori reason and introspection.

·         Distrust the senses or sensory knowledge.

·         Some ideas (the most reliable) are innate, born in us.


Ex: Plato, Anselm and Descartes

 

Continental Rationalists: 3 prominent rationalists at the time

René Descartes (French- 1596-1650)
Baruch Spinosa (Portuguese/Dutch 1632-1677)
Gottfried Liebniz (German- 1646-1716)

 

2. Empiricists
 

·         The only way to acquire knowledge is through the senses (nothing is in the mind without first being in the senses)

·         Deny the existence of innate ideas;

·         Share a certain confidence in reason but mostly to be legitimate any idea must trace back to or relate to experience.

 

Ex: Aristotole, St. Thomas Aquinas

 

British Empiricists: 3 prominent empiricists

John Locke (English 1632-1704)
George Berkeley (Irish 1685-1753)
David Hume (Scottish 1711-1776)

 

Epistemology - the branch of philosophy that is concerned with knowledge and justification

 

Descartes was a contemporary - Galileo Galilei (1564 - 1642).  The latter is considered founder of Modern Physics.  Among other things he used the telescope to investigate solar system.

 

Dispute at the time: the nature of the heavens and earth

 

Geocentric theory - earth at center and everything revolves around it (church supported this theory).

Heliocentric theory - sun at center (Copernicus theory)

 

Two views had nearly equal explanatory/predictive power (by the time of Galileo), but Heliocentric theory much more elegant/simple.

Still, the moon DOES orbit earth- on either account.

 

Galileo was commissions to write an analysis thesis comparing the 2 theories.  When he looked as other planets through the newly invented telescope, he found that other planets had moons of their own. Therefore there was nothing exceptional about the moon orbiting the Earth.  In fact the new findings were more consistent with Heliocentric theory. This really removed the last bit of support recommending the Geocentric model over the Heliocentric model.

 

Galileo defended his views in Dialogue Concerning the Two Chief World Systems (1632),  In 1633, Galileo was convicted of "grave suspicion of heresy" based on the book, which was then placed on the Index of Forbidden Books  It was not removed from that list 1835.  He was forced to recant, and lived under house arrest for the rest of his life.

 

This was a HUGE revolution in science/ knowledge in Western culture.  Humans had been wrong, and wrong in some pretty fundamental ways, for thousands of year.  Plus. A lot of other long held beliefs were being over turned.  (e.g. "Objects of different weights fall at different rates of speed."- Aristotle said so; everyone believed he was right.  Galileo proved Aristotle was wrong, and always had been.)

 

Descartes was trying to deal with these the new revolutions.

 

Further, as a mathematician, he was impressed by Greek math (compare to lousy Greek physics and science and medicine)

 

·         Questioned: Why the dissimilarity?

·         Decided it was a question of structure.

o   Math had a foundation and method while science had neither.

·         Sought a foundation for all knowledge: 

 

Quest for Certainty

 

His plan was to build up from a certain, indubitable truth or set of certain truths an edifice of knowledge that would not be vulnerable to the kinds of errors and revolutions plaguing medieval science.

 

2 parts to Descartes

 

1. Methodological Doubt - negative project

2. Reconstruct Knowledge - positive project - everything founded on me then God then higher up reason.

 

Methodological Doubt

 

To find a belief or beliefs that were indubitable, he tried to doubt the beliefs he had.  If he found one he couldn’t doubt, he would have found his certain/ indubitable belief.

 

Set the bar very high- "beyond a shadow of a doubt."

 

3 categories for his beliefs (divided according to the way he came to believe them)

 

1.      beliefs on a basis of authority

2.      beliefs based on own experience

3.      beliefs based on reason

 

Finds each category doubt-able.

 

#1 is doubt-able because they might be lying or mistaken.

 

#2 is doubt-able because My senses are not sufficiently keyed into reality and therefore not sufficiently reliable as dream experience proves.

 

#3 is doubt-able because I cannot be certain that an evil demon does not exist who is so powerful that he could fool even my reason.  If such a being is possible (and there is no reason to suppose he isn’t) then I could be wrong when I draw conclusions based on reason.

 

Is ANYTHING indubitable.

 

Might he even be wrong in thinking that he exists?  My the evil demon fool him even about the reality of his own existence?

 

Tries to doubt his own existence:

 

“I doubt that I…

 

Impossible

 

In the very act of doubting- or any kind of thinking, I know that I am.

 

Or famously:

 

"Cogito ergo sum."

 

"I think therefore I am"

 

Not an argument, but rather known because it is a “clear and distinct” idea before the mind’s eye.

 

But... Where to from there?   He seems stuck in Solipsism, which was NOT the plan remember.

 

Solipsism- belief that one is the only thing that exists in the universe and everything else is part of imagination

 

Descartes Rationalist Re-Construction of Knowledge

 

1. I'm a thinking thing (at least a mind).

 

Descartes Theory of Mind:

 

Descartes claims that the mind is different from the body.  One can doubt one has a body but one cannot doubt one has a mind.  This, he thinks, proves that the two are distinct.

 

Note: But this may not be a very good argument.  I don’t doubt that Peter Parker is meeting me for tea this afternoon, but I do doubt that Spiderman is meeting me for tea.  Does this prove that Peter Parker is not Spiderman?

 

But he gives other reasons for thinking that mind and body are distinct.  The general point he makes is that “mental things” have properties that “physical things” do not have and vise verse. 

 

The mind is immaterial-not a body, no location, private, incorrigible.
There are 2 kinds of substances –besides God (mind/body dualist)

1. material
2. immaterial (mental)
They are radically different.

Dualism has problems when it comes to theory of mind;

How does what is immaterial interact with what is material?  Objection: where does the mind touch the body?; If really immaterial “you” don't exist anywhere and yet somehow the dualist believe that “your” mind is making “your” body move around and responds to its “sensations.”


Descartes wants to get rid of the possibility of an Evil demon so that he doesn't have to worry about

Only one thing is Big and Good enough to do the job: God.  He therefore attempts to prove that God exists.

He knows that he is a thinking being; therefore he is a thing with thoughts and one happens to be the thought of God.

 

Argument of existence of God

 

Number

Proposition

Justification

1.       

I have the idea of a perfect being.

Given by introspection

2.       

I have a perfect idea.

Follows from #1

3.       

An effect cannot be greater than its cause.

Metaphysical or physical principle

4.       

I am not perfect.

Given by introspection

5.       

I cannot be the cause of my perfect idea.

3 & 4

6.       

Only a perfect being can cause a perfect idea.

3

7.       

A perfect being exists.

2&6

8.       

God exists

7

 

Trying to go from the fact that he has an idea of God to certain knowledge that God exists. Since I have this idea the only thing that can explain this idea is God.

 

This means:

 

1. There is no evil demon because  God is a good, etc. Therefore we can trust reason (logic and math).

 

2. Because God is good and we have been created by Him, made for the world and the world for us, we CAN trust our senses so long as we do not extend our will to believe beyond what the evidence warrants.

 

Note: He never attempts to restore authority as a mode of justification.  Individual authority replaces institutional authority.  Radical idea to Thomistic Scholasticism.  Ushering in the Modern Era.  Descartes is called the first Modern Philosopher.

 

Out trust in our own mind and in our own senses depends on trust in an benevolent God.  If we didn't live in a divinely governed benevolent universe we would have no reason to trust our mind or to trust our senses.  If you give up on God you have to give up of your own ability to Know.  Absent the notion of God on what grounds can you trust your reasons or your senses?

 

Problems:

 

3 major problems with Descartes argument

 

1. Do you really have a perfect idea of God or perhaps do you have an imperfect idea of a perfect being? If the idea is imperfect then it wasn't caused by God.  He could have come up with it.

 

2. “An effect cannot be greater than its cause.”  This is either a physical or a metaphysical principle.  But If he is doubting his senses why is he using a physical principle? If he is doubting his reason why is he using a metaphysical principle.

 

3. It’s an Argument.  But, if doubting reason one cannot use reason to justify reason.  That’s begging the question. (Circular)

Was looking for something basic principle to explain all.