4 Descartes, Rationalism and the Enlightenment

René Descartes!(1596 - 1650)!

“The Father of Modern Philosophy”"

“There are only six simple and primitive passions, i.e. wonder, love, hatred, desire, joy, and sadness. All the others are composed of some of these six, or are species of them.”

René Descartes, On the Passions of the Soul (1649)"

Discourse on the Method (1637)

Meditations on First Philosophy

(1641)

methodological skepticism

1.  If there are propositions that can potentially be false, then we should temporarily assume that they are false."

2.  We should accept as true only those propositions of which we can have absolute certainty."

3.  The propositions of which we have absolute certainty should become the foundation of our knowledge."

knowledge"

Galen (129 – 199)! Andreas Vesalius (1514 – 1564)"

Reading from Galen, early

1500s"

knowledge"

Meditation I!

“Of The Things of Which We May Have Doubt”"

“adventitious knowledge”

Knowledge acquired through the senses."

“clear and distinct knowledge”

Knowledge that cannot be doubted."

“dualism”

Meditation II!

“Of the Nature of the Human Mind; and That It Is More

Easily Known Than the Body”"

“The Wax Argument”

How do we recognize a piece of wax?!

!  By its touch."!  By its shape."!  By its color."!  By its temperature."

We recognize wax by the features we learn through our senses.!

!  Wax can change shape."!  Wax can feel different."!  Wax can change color."!  Wax can change temperature."

Yet we still recognize that it is the same wax.!

The sensory features of wax can change.!

1. The features of wax that we experience through our senses can change."

2. If a piece of wax changes its features, we can still identify it as the same piece of wax."

3. Therefore, the identity of the wax is determined by something other than its sensory features."

1. The brain is responsible for processing sensory information."

2. Therefore, the brain is not responsible for our ability to identify wax."

3. The mind is responsible for our ability to identify wax."

“mind/body dichotomy”!

“But what then am I? A thinking thing.”

a priori knowledge: independent of empirical experience!

a posteriori knowledge: dependent on empirical experience

Meditation III!

“Of God: That He Exists”"

Ontological Argument

An argument that tries to prove the existence of God through

intuition and reason alone (not through empirical means)."

Ontological Argument!

1.  God is, by definition, the greatest conceivable being."

2.  An existent being is greater than a non-existent being."

3.  Therefore God, by definition, exists."

Descartes’s Ontological Argument!

“Certainly, the idea of God, or a supremely perfect being, is one that I find within me just as surely as the idea of any shape or number.” [Meditation V]"

Descartes’s Ontological Argument!

“From the fact alone that I cannot conceive of God except as existing, it follows that existence is inseparable from him, and consequently that he does, in truth, exist.” [Meditation V]"

1. It is impossible to conceive of a circle except as round."

2. It is impossible to conceive of the number 2 except as an even number."

3. It is impossible to conceive of God except as a perfect being."

1.  God is a perfect being."2.  A necessary being is more perfect

than an unnecessary being."3.  An existent being is more perfect

than a non-existent being."4.  Therefore, God necessarily exists."

Isaac Newton"(1643 - 1727)!