René Descartes,MeditationsIntroduction to Philosophy

Jason M. Chang

Learning Outcomes

1. Background

2. Descartes’ project in the Meditations

3. Descartes’ method

4. “Cogito, ergo sum”

5. The appearance/reality gap

Background

• Biography

• Meditations on First Philosophy (1647)

Rene Descartes 1596-1650

Background

• Historical context

o Scientific revolution

o Expansion of human knowledge

Descartes’ project in the Meditations

Descartes project

Background

• Knowledge = justified true belief

• Foundationalism

o Definition

o Example1, Example 2

x

yz

I know that x + y = 90 degrees

Z = 90

x + y + 90 = 180

x + y = 90

x + y + z = 180

FOUNDATIONAL BELIEFS

C3 is 3

C2 = 1

C1 = 2A2 and B2 are

combo of 2 and 3

A1 = 1

B1 = 3

B2 = 2A1 = 3

B3 = 1A3 = 2Ken Ken Puzzle

Descartes project

• Problem of doubtful beliefs

• Descartes’ question

o What can serve as a foundation for scientific truths?

• Aim of MeditationsPublished in 1647

Descartes’ method

Descartes’ method

What scares Descartes

“It is now some years since I detected how many were the false beliefs that I had from my earliest youth admitted as true, and how doubtful was everything I had since constructed on this basis.”

Descartes’ method

Descartes’ method

• “If in doubt, throw it out”

• Method of “Cartesian doubt”

o What it iso Its aimo Methodological NOT genuine doubt

Are there any beliefs that cannot be doubted that can serve as a foundation for scientific knowledge?

Descartes’ method

Descartes’ method

Candidate #1: Beliefs derived from senses

• Senses are deceptive

• The dream argument

Descartes’ method

Descartes’ Dream Argument

(P1) I often have perceptions when I am dreaming like the ones I have now.

(P2) There is no definite signs to distinguish between dream experience and waking experience.

Therefore,

(C) It is possible that I am dreaming right now and that my perceptions are false.

Descartes’ method

Candidate #2: Beliefs derived from reason

• Evil demon argument

Descartes’ method

Descartes’ Evil Demon Argument

(P1) It is possible that an evil demon is deceiving me when I reason to conclusions.

Therefore,

(C) It is possible that the conclusions I derive from reason are false.

Descartes seems to have shown that there are no indubitable beliefs that can serve as a foundation for science.

Descartes’ method

Descartes’ method

What this means

• Wrong interpretation

• Right interpretation

o No solid foundation for knowledge

o Beliefs from science no better than beliefs from faith

o Skepticism (???)

“Cogito ergo sum”

“Cogito, ergo sum”

• Translation

• The passage

“Let [the evil demon] deceive me as much as he will, he can never cause me to be nothing so long as I think that I am something. So that after having reflected well and carefully examined all things, we must come to the conclusion that this proposition; I am, I exist, is necessarily truth each time that I pronounce it or that I mentally conceive of it.”

“Cogito, ergo sum”

• Descartes’ reasoning

(P1)  Even if we assume that there is a deceiver, from the very fact that I am deceived it follows that I exist.

(P2) More generally, whenever I think (e.g., feel, sense, imagine, reason), it is affirmed I exist.

(P3) I think.

Therefore,

(C) I exist.

“Cogito, ergo sum”

• Others things that cannot be doubted

o Experience claims vs. Reality claims

o Experience claims cannot be doubted

The appearance/reality gap

The appearance/reality gap

How can we know that objects as they appear to us is how objects

really are?

The appearance/reality gap

Clear and distinct ideas

• “Myself as an existing thing” is clear and distinct

• Ideas and perceptions that are clear and distinct are true

• I have a clear and distinct idea of perfection

The appearance/reality gap

Descartes’ argument for God

(P1) The idea of perfection must have a cause.(P2) I am an imperfect being.(P3) It is impossible for an imperfect being to be the source of the idea of perfection.So,(P4) I cannot be the source of the idea of perfection.

Therefore,

(C) The source of the idea of perfection must be a Perfect Being (God).

The appearance/reality gap

Descartes’ argument bridging the gap

(P1) God, who is perfect, cannot be a deceiver.

So,

(P2) God would not mislead me when I perceive something clearly and distinctly.

Therefore,

(C) Whenever I perceive something clearly and distinctly, it must be true.

The appearance/reality gap

Part of Descartes’ legacy

How can we know that objects as they appear to us is how objects

really are?