Epistemology Section 1

• What is knowledge?

• Why are knowledge claims a problem in Philosophy?

• Can knowledge claims be justified?

Epistemology Section 1

• What is knowledge?– The distinction between knowing ‘how’ and

knowing ‘that’.– Tripartite theory (justified, true, belief)– The difference between knowledge, belief and

certainty

Epistemology Section 1

• Why are knowledge claims a problem in Philosophy?– The difference between appearance and reality (Plato’s

simile of the cave’ / Matrix)

– Problems with the Tripartite theory• Accidental correctness (Gettier)

• The problem of justification (challenge of scepticism)– Infinite regress of justification

– Unreliability of the senses

– Limitations of reason

Epistemology Section 1

• Can knowledge claims be justified? (Responses to scepticism)– Rationalism (e.g. Descartes, Plato)

• Innate ideas

• Senses are unreliable

• Self-evident truths can be grasped by the mind without reference to the senses

• Reason is the most reliable source of knowledge about the world

Epistemology Section 1

• Can knowledge claims be justified? (Responses to scepticism)– Problems with rationalism …

• Can only give us indirect knowledge about concepts

• A priori truths tell us nothing important about the world

• Problems with innate ideas

Epistemology Section 1

• Can knowledge claims be justified? (Responses to scepticism)– Empiricism (e.g. Hume, Aristotle)

• The mind as tabula rasa

• Experience as the source of all ideas (concepts)

• Reason can only give logical connections between ideas not knowledge about the world

• Only experience gives us knowledge about the world.

Epistemology Section 1

• Can knowledge claims be justified? (Responses to scepticism)– Problems with Empiricism

• The difference between appearance and reality

• How do we do that our mental representation correspond to reality?

• How can we deal with the problem of radical doubt?

Epistemology Section 2

• Option A: Descartes’ Rationalism

Or

• Option B: Hume’s Empiricism

Descartes’ Rationalism

1. Searching for a reliable foundation for knowledge

2. Reason as the foundation of knowledge:

3. Refuting sceptical arguments:

Descartes’ Rationalism1. Searching for a reliable foundation for

knowledge.– Aim of the Meditations …– How is Descartes going to achieve his aim?

(Sceptical Method)• Authorities as a foundation of knowledge?• A posteriori truths as a foundation of knowledge?• A priori truths as a foundation of knowledge?

Descartes’ Rationalism1. Searching for a reliable foundation for

knowledge.– A posteriori truths as a foundation of knowledge?– Mistrust of the senses Med. I

• Failed me in the past …• Perceptual illusions …

– Maybe I’m mad?– The Dream argument Med. I

• Hypothetical possibility• Extreme argument against a posteriori knowledge• Maths / external world survive

Descartes’ Rationalism1. Searching for a reliable foundation for

knowledge.– A priori truths as a foundation of knowledge?– The Evil Genius argument Med. I

• Hypothetical possibility• Extreme argument against a priori knowledge• Makes sure he avoids slipping back into old habits• Allows him to ‘turn his will in the opposite direction’• If anything survives this he can truly say that he has found

certainty – Everything is lost …

Descartes’ Rationalism

2. Reason as the foundation of knowledge:– The Cogito Med. II

• Non-analytical self-evident truth

• It’s a self-authenticating statement (true every time it is conceived by the mind)

• It’s self-contradictory to say “I don’t exist”

• Survives even the demon argument

• ‘Thinking’ survives whereas nothing based on sense experience does

• Opens the way to his mind/body dualism

• It is the one indubitable certainty that can act as a foundation for all others.

Descartes’ Rationalism

2. Reason as the foundation of knowledge:– God as the guarantor of clear and

distinct perceptions Med. III• Clear and distinct perception / rule

• Trademark argument for God’s existence

• The idea of God includes the notion that he is benevolent

• If God is good he would not deceive us

• Clear and distinct perceptions must be true since a good God wouldn’t allow this level of deception

Descartes’ Rationalism

3. Refuting sceptical arguments: Med. VI

– God is no deceiver therefore material reality exists– Errors in sense perception can be recognised and

corrected – Refuting the dream argument

Descartes’ Rationalism

3. Refuting sceptical arguments:– God is no deceiver therefore material reality exists

Med. VI

• Strategy relies on clear and distinct rule / proof that God exists and is good.

• Physical objects: – are not subject to Descartes’ will

– are extended whereas the mind is unextended

– These objects can’t originate, therefore, in the imagination …

– Where then do they come from?

Descartes’ Rationalism

3. Refuting sceptical arguments:– God is no deceiver therefore material reality exists

Med. VI

• We passively receive ideas of outside objects, so there must be an external cause to the ideas.

• The only possible cause of these ideas are the external objects themselves, or God, or the demon.

• God exists and is good, therefore, he wouldn’t allow us to think these ideas were caused by external objects unless they actually existed

Descartes’ Rationalism

3. Refuting sceptical arguments:– Errors in sense perception can be recognised and

correctedMed.

VI• Strategy relies on clear and distinct rule / proof that

God exists and is good.

• Difference between the imagination and the intellect– Imagine a chiliagon

– Use the intellect to understand a chiliagon

– Imagination and the intellect are distinct faculties of the mind

» Imagination deals with images of material things

» Intellect deals with a priori truths

Descartes’ Rationalism3. Refuting sceptical arguments:

– Errors in sense perception can be recognised and correctedMed.

VI• There is an outside world but is it like that reported by my senses?

– Primary / Secondary qualities

– Secondary (apparent) qualities (colour, smell, taste)

» Originate in sensation

» Subject matter of the imagination

» Obscure and confused perception (prone to error)

» Do not exist in the object (appear only in the perceiving mind)

– Primary (or real) qualities (shape, position, size, number)

» Subject matter of mathematics

» Understood in the intellect

» Perceived clearly and distinctly

» Exist in the objects (inherent features of matter itself)

Descartes’ Rationalism3. Refuting sceptical arguments:

– Errors in sense perception can be recognised and correctedMed.

VI• For example

– ‘Grass is green’, we should say ‘Grass stimulates sensations of green in us’

– ‘The tower is small’ – we should say ‘the tower simply appears small and my memory and other faculties can confirm its true size’.

• God equips us with various faculties: Reason, the senses, memory.

• I now see it is ‘…impossible that there could be any falsity in my opinions which couldn’t be corrected by some faculty supplied by God’.

• Some things which my senses appear to be telling me are in fact a misjudgement of reason

• However, with a careful use of clear reasoning we can correct the errors in sense perception.

Descartes’ Rationalism

3. Refuting sceptical arguments:– Refuting the dream argument Med. VI

Problems with Descartes’ Rationalism

• Problems with the sceptical method …

• Problems with the cogito …

• Descartes’ arguments rely on a good God

• Descartes’ appeal to the clear and distinct rule– What might seem clear and distinct might not be

true at all– Logical error …

• Cartesian circle …