Phil 102 Descartes 1(1)

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The Enlightenment

An Experiment on a Bird in the Air Pump, by Joseph Wright

of Derby, 1768,

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Knowledge of the External World

This lecture will help youunderstand:

• The Age of Enlightenment – Scientific Revolution (Galileo,

Kepler, and Newton) – French Encyclopedists

– Democracy and Liberalism

• Descartes’ “Geometrical”

Method• Metaphysical Doubt and the

Hypothesis of the Evil Genius

Rene Descartes

(1596-1650)

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Question 1:

What time, place, and person is most associatedwith “the Enlightenment”?

A. 6th century BC (India—the Buddha)

B. 6th century (China--Confucius)

C. 18th century (Europe--Newton)

D. 19th century (United States--Edison)

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The Enlightenment

– The Enlightenment (English) – Lumières (French)

– Aufklärung (German)

– Note the importance of the

metaphor of “light.”

Nature and Nature’s laws lay

hid in night:

God said, Let Newton be! And

all was light! (Alexander Pope

1688 – 1744)

The Alchemist in Search of the

Philosopher's Stone, by Joseph

Wright, 1771

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The Orrery

( mechanical model

of the solar system),

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Revolutionary

• This era begins in the 17th century and

continues into the 18th century.

• The Enlightnment is revolutionary in every

sense of the word.

1. Driving force behind the two great political

revolutions at the end of the 18th century.

2. Time of revolutionary ideas and liberal and

progressive thinking in the sciences . . . .

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The Scientific Revolution

– For the long centuries of the Middle Ages (500-

1350 AD) there was hardly any advance in

scientific knowledge. During this period there was

little scientific inquiry and experimentation.Rather, students of the sciences simply read the

works of the alleged authorities and accepted

their word as truth.

– However, during the Renaissance this doctrinalpassivity began to change, beginning with Nicolas

Copernicus . . .

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Heliocentricity

Nicolaus Copernicus

(1473-1543)

Polish astronomer who

advanced the theorythat the earth andother planets revolvearound the sun,

disrupting thePtolemaic system ofastronomy.

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Johannes Kepler (1571-1630)

• Johannes Kepler (1571-1630) provedthat Mars moved in an elliptical orbit.He went on to conclude that allplanets move in ellipses, with thesun at one focus. This became known

as Kepler's first law of planetarymotion.

• However, it did not offer an effectivemodel of the solar system based onobservational data.

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Galileo Galilei (1564-1642)

• Galileo Galilei, who in

1630 published his

Dialogue on the Two

Chief Systems of the

World , in which he

supported the

Copernican, orheliocentric theory of

the universe.

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Isaac Newton (1642-1727)

• English mathematician and

scientist who invented

differential calculus and

formulated the theories ofuniversal gravitation,

terrestrial mechanics, and

color. His treatise on

gravitation was presented in

Principia Mathematica

(1687).

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• Gradually, as scientists and philosophers cameto discover more and more scientific andmechanical laws which could explain thenatural world, the old theological discussions

seemed out of date or passé.• Now it was now science, philosophy and

reason that could provide the tools necessaryto ensure progress and improvement of the

human condition.

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Encyclopédie

• Encyclopédie is famous for itsanticlericalism, its devotion to science,

its faith in the power of reason to bring

about societal change, and its

optimistic tone.

• Greatest expression of the idea of

progress ever written down.

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Les Philosophes

• Denis Diderot (1713-1784) was the main editor.

• Jean le Rond D’Alembert (1717-1783)

• Voltaire (pen name of François-Marie Arouet)

(1694-1778)

• Jean-Jacques Rousseau (1712-1778)

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“Optimism”

• If there is one word that could best

characterize the Enlightenment of the 17th

and 18th centuries, it is “optimism,” the belief

in progress, and the possibility of “man”

securing the means to his own salvation.

Human beings would do this not with God's

help but through their own reason andintellect.

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• In his essay, “Answering theQuestion: What is

Enlightenment?” Kant said the

Enlightenment was:

• “Mankind’s final coming of

age, the emancipation of the

human consciousness from an

immature state of ignorance

and error.”

Immanual Kant

(1724-1804)

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Universal Reason

• Everybody was to benefit from the

Enlightenment, because everybody was

considered to possess an innate, virtually

equal capacity for rational thinking.

• All that is required is the proper education

and political institutions to allow people to

realize their rational capacities and natures,and make for a better world.

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Democracy and Liberalism

• This optimistic faith in science, reason,freedom, progress and universal education is afundamental principle of American democraticthinking.

• It is the time of the emergence of Westerndemocracy, more than two thousand yearsafter the early experiment in Attic Greece.

• The framers of the American constitution—

people like Benjamin Franklin, ThomasJefferson, James Madison—were all “childrenof the Enlightenment.”

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René Descartes (1596-1650)

• Meditations on

First Philosophy

(1641)

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Error and Errancy

• According to Descartes, philosophy had strayed

from the path of certainty and true knowledge

in the Middle Ages.

• This is because it lacked any firm foundation or

method by which it would be possible to attain

knowledge with the certainty and accuracy and

precision of mathematics.

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Follow the Leader: Geometry

• If philosophy is to arrive at knowledge, then it

must follow the example of mathematics and

geometry, which proceeds by a strict method

of deduction and proof.

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Rationalism

• Rationalism (from Latin, ratio, reason)—

sometimes called “innatism.” Belief that reason is

the prime source of knowledge, and that it is

possible to know things prior to experience.

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Empiricism

• Empiricism (from Gk, empeiria, experience)—

the view that all knowledge derives from

experience, and that all ideas can be traced

back to the senses (sight, touch, hearing, etc.).

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A Fresh Start

• As one of the first

thinkers of the

Enlightenment, René

Descartes’ (1596-1650)philosophical goal was to

make a fresh start and

putting philosophy backon track again.

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“It is now some years since I detected howmany were the false beliefs that I had frommy earliest youth admitted as true, andhow doubtful was everything I had since

constructed on this basis; and from thattime I was convinced that I must once andfor all seriously undertake to rid myself ofall the opinions which I had formerlyaccepted, and commence to build anewfrom the foundation, if I wanted to

establish any firm and permanentstructure in the sciences. But as thisenterprise appeared to be a very greatone, I waited until I had attained an age somature that I could not hope that at any

later date I should be better fitted toexecute my design. This reason caused meto delay so long that I should feel that Iwas doing wrong were I to occupy indeliberation the time that yet remains tome for action.” (IP 205)

Edifice of Knowledge

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Descartes’ Method

• By “method” Decartes means reliable rules

which are easy to apply and such that if one

follows them exactly one will never take

what is false to be true.

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Mathesis Universalis“The long chains of simple and easy reasonings by

means of which geometers are accustomed to reach theconclusions of their most difficult demonstrations, hadled me to imagine that all things, to the knowledge ofwhich man is competent, are mutually connected in thesame way, and that there is nothing so far removed from

us as to be beyond our reach, or so hidden that wecannot discover it, provided only we abstain fromaccepting the false for the true, and always preserve inour thoughts the order necessary for the deduction ofone truth from another.” (Discourse on Method ) (IP 204)

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Sub-method

– “methodological doubt”

– “metaphysical doubt”

– “hyperbolic doubt”

– “radical doubt”

– “radical skepticism”

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Method of Doubt

• This method is merely part—albeit an

important part—of Descartes’ more general

“mathematical method.”

• Doubt is his way of arriving at simple, self-

evident starting point or foundation on which

the world of knowledge is to be built anew.

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Demolition: “Upheaval of my

former opinions”

“To-day, then, since very opportunely for the planI have in view I have delivered my mind from

every care [and am happily agitated by no

passions] and since I have procured for myself anassured leisure in a peaceable retirement, I shall

at last seriously and freely address myself to the

general upheaval of all my former opinions.” (IP

205)

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Archimedean Point

“Archimedes, in order that hemight draw the terrestrialglobe out of its place, andtransport it elsewhere,demanded only that onepoint should be fixed andimmoveable; in the same wayI shall have the right toconceive high hopes if I am

happy enough to discover onething only which is certainand indubitable.” (IP 223)

Science

And

Knowledge

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• “ Indubitable” : not susceptible to doubt

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Objects of Doubt

Sense perception(Illusion)

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Duck or Rabbit?

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Fooled ya!

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“All that up to the present time I have

accepted as most true and certain I have

learned either from the senses or through the

senses; but it is sometimes proved to me thatthese senses are deceptive, and it is wiser not

to trust entirely to anything by which we have

once been deceived” (IP 205-206).

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Objects of Doubt

• Sense perception (Illusion)

• Sense perception (dreams)

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Objects of Doubt



• The components of dreams

themselves

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Objects of Doubt



• The components of dreams themselves

• Universals, Definitions, and

Mathematical truths, etc.

2 + 3 = 5?

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“For whether I am awake or asleep, two and

three together always form five, and the

square can never have more than four sides,

and it does not seem possible that truths soclear and apparent can be suspected of any

falsity [or uncertainty].” (IP 207)

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The Evil Genius

“I shall then suppose,

not that God who is

supremely good and the

fountain of truth, butsome evil genius not

less powerful than

deceitful, has employed

his whole energies indeceiving me” (IP 208)

Q ti 2

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Question 2:If Descartes were alone today, rather than the

evil genius, he would used the example of whichmovie to illustrate his point?

A. InterstellarB. Harry Potter

C. E.T.

D. The Matrix

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The Matrix . . . .

Documents

Phil 102 Descartes 1(1)