Transcript
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LECTURE 15: CERTAINTY

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TODAY’S LECTURE

In Today’s Lecture we will:In Today’s Lecture we will:

1.1.Review Hume’s radical empiricism and its consequencesReview Hume’s radical empiricism and its consequences

2.2.Outline and investigate Kant’s theory of knowledge: Outline and investigate Kant’s theory of knowledge: Transcendental Transcendental IdealismIdealism

3.3.Discuss whether Kant’s theory overcomes Hume’s radical empiricismDiscuss whether Kant’s theory overcomes Hume’s radical empiricism

4.4.Conclude our investigation into the theory of knowledgeConclude our investigation into the theory of knowledge

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RECAP: DAVID HUME

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DAVID HUME

David Hume’s PhenomenalismDavid Hume’s Phenomenalism

All knowledge is derived from and limited to appearancesAll knowledge is derived from and limited to appearances

Appearances are presented to us in our perceptionsAppearances are presented to us in our perceptions

Perceptions can be divided between Perceptions can be divided between

1.1. ImpressionsImpressionsLively, Vivid SensationsLively, Vivid Sensations

2.2. IdeasIdeasPale impressions / copiesPale impressions / copies

All ideas are derived from impressionsAll ideas are derived from impressions

All the mind possesses is a collection of perceptionsAll the mind possesses is a collection of perceptions

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DAVID HUME

David Hume’s PhenomenalismDavid Hume’s Phenomenalism

There are two types of knowledge:There are two types of knowledge:

1.1. Relations of IdeasRelations of IdeasIdeas that are intuitively or demonstratively certainIdeas that are intuitively or demonstratively certain

E.g. Geometry, Arithmatic, Logic, Algebra etc.E.g. Geometry, Arithmatic, Logic, Algebra etc.

2.2. Matters of FactMatters of FactIdeas that pertain to the worldIdeas that pertain to the world

E.g. The sun will rise tomorrow, This chair is red, etc.E.g. The sun will rise tomorrow, This chair is red, etc.

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DAVID HUME

David Hume’s attack against abstract knowledgeDavid Hume’s attack against abstract knowledge

Empirical (all) knowledge can only be either:Empirical (all) knowledge can only be either:

Necessarily true but not informativeNecessarily true but not informativeOrOr

Informative but not certainInformative but not certain

All ideas are derived from appearancesAll ideas are derived from appearances

Any idea we have that is NOT derived from appearances should be Any idea we have that is NOT derived from appearances should be abandonedabandoned

When we run over libraries, persuaded of these principles, what havoc must we make? If we take in our hand any volume, of

divinity or school metaphysics, for instance; let us ask, “Does it contain any experimental reasoning concerning matter of fact and existence?” No. Commit it then to the flames: for it can

contain nothing but sophistry and illusion.

(David Hume, Textbook, p.225)

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DAVID HUME

According to Hume we must abandon the following abstract concepts:According to Hume we must abandon the following abstract concepts:

oThe concept of causationThe concept of causationWe never perceive a necessary cause; only succession and We never perceive a necessary cause; only succession and

contiguitycontiguity

oThe selfThe selfWhen we reflect we never find a thinking thing; only many different When we reflect we never find a thinking thing; only many different perceptionsperceptions

oThe concept of substanceThe concept of substanceWe never perceive substanceWe never perceive substance

Furthermore:Furthermore:

All scientific knowledge is informative but not certainAll scientific knowledge is informative but not certain

We must recognize how limited our perceptions are and limit our We must recognize how limited our perceptions are and limit our knowledge accordinglyknowledge accordingly

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KANT

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IMMANUEL KANT

Outline:

Lived 1724-1804

Represents an important turning point in epistemology

Wrote the Critique of Pure Reason in response to Hume’s radical empiricism

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IMMANUEL KANT

Prelude to Kant’s theory of knowledge:Prelude to Kant’s theory of knowledge:

Kant was heavily influenced by Hume’s radical empiricismKant was heavily influenced by Hume’s radical empiricism

““I openly confess my recollection of David Hume was the very thing I openly confess my recollection of David Hume was the very thing which many years ago first interrupted my dogmatic slumber and gave which many years ago first interrupted my dogmatic slumber and gave

my investigations in the field of speculative philosophy a quite new my investigations in the field of speculative philosophy a quite new direction”direction”

(Textbook, p.232)(Textbook, p.232)

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IMMANUEL KANT

Kant maintains the following:Kant maintains the following:

Kant rejects the empiricist claim that the mind is a ‘blank-slate’Kant rejects the empiricist claim that the mind is a ‘blank-slate’

He also rejects the rationalist claim that we possess innate ideasHe also rejects the rationalist claim that we possess innate ideas

Unlike Hume Kant claims we can be Unlike Hume Kant claims we can be certaincertain that: that:

Every event must have a causeEvery event must have a cause

Substance existsSubstance exists

The self existsThe self exists

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KANT’S THEORY OF KNOWLEDGE

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A PrioriA Priori

Independent of sensesIndependent of senses

UniversalUniversal

CertainCertain

A PosterioriA Posteriori

Derived from sense Derived from sense experienceexperience

SpecificSpecific

Not certainNot certainKANT’S THEORY OF KNOWLEDGE

A PrioriA Priori

Independent of sensesIndependent of senses

A PosterioriA Posteriori

Derived from sense Derived from sense experienceexperience

AnalyticAnalytic

True by definitionTrue by definition

No relevance to realityNo relevance to reality

SyntheticSynthetic

Not logically certainNot logically certain

Kant’s understanding of ‘knowledge’

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KANT’S THEORY OF KNOWLEDGE

Activity: List any knowledge that corresponds to the following Activity: List any knowledge that corresponds to the following categories:categories:

Synthetic Synthetic a posteriori a posteriori KnowledgeKnowledgeThe room is redThe room is redThe moon is 2159 miles in diameterThe moon is 2159 miles in diameter

Analytic Analytic a priori a priori knowledgeknowledgeAll bachelors are unmarried menAll bachelors are unmarried menA triangle is a three sided closed shapeA triangle is a three sided closed shape

Analytic Analytic a posteriori Knowledgea posteriori Knowledge

Informative but not certain

Certain but not informative

Analytic a posteriori knowledge is not possible!

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KANT’S THEORY OF KNOWLEDGE

The search for synthetic The search for synthetic a priori a priori knowledgeknowledge

Kant wants knowledge which is certain, not derived from experience, Kant wants knowledge which is certain, not derived from experience, and still informativeand still informative

It must be both It must be both SyntheticSynthetic and and a prioria priori

Informative, not just Informative, not just true by definitiontrue by definition

Necessary & UniversalNecessary & Universal

For Example:

Every event has a causeSubstance existsThe Self exists

The big question is whether such knowledge exists!

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KANT’S THEORY OF KNOWLEDGE

Traditional theories of knowledge

Traditional theories of knowledge are concerned with asking whether our idea of the apple corresponds to the apple itself

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KANT’S THEORY OF KNOWLEDGE

Kant’s Copernican Revolution

Instead of asking how our knowledge conforms to objects in the world;

Kant asks how objects in the world must conform to us

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KANT’S THEORY OF KNOWLEDGE

Kant’s theory of knowledgeKant’s theory of knowledge

Synthetic Synthetic a priori a priori (SAP) knowledge is not (SAP) knowledge is not derived derived from experiencefrom experience

SAP is the SAP is the basisbasis for experience for experience

SAP defines SAP defines howhow we experience we experience

Our minds possess innate structures called ‘categories of the Our minds possess innate structures called ‘categories of the understanding’understanding’

UnityUnityPluralityPluralityTotalityTotalityRelations of substance and characteristics of substanceRelations of substance and characteristics of substanceRelations of cause and effectRelations of cause and effectRelations of reciprocityRelations of reciprocity

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KANT’S THEORY OF KNOWLEDGE

Space and TimeSpace and Time

Space and Time are both Space and Time are both a priori a priori conditions for all experienceconditions for all experience

ALL objects must be in space and time to be experiencedALL objects must be in space and time to be experienced

Kant maintains that space and time are contributed by our mindsKant maintains that space and time are contributed by our minds

We can have no knowledge of an object which is not in space or timeWe can have no knowledge of an object which is not in space or time

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KANT’S THEORY OF KNOWLEDGE

Kant’s disagreement with Hume:Kant’s disagreement with Hume:

Hume maintained that belief in the following is irrational:Hume maintained that belief in the following is irrational:

CausalityCausalityThe selfThe selfSubstanceSubstance

For Kant these concepts are not only certainly true; They For Kant these concepts are not only certainly true; They must must be true!be true!

They are They are universaluniversal and and necessarynecessary for experience for experience

If they were not true then we would not be able to have experienceIf they were not true then we would not be able to have experience

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KANT’S THEORY OF KNOWLEDGE

Summary:Summary:

Unlike Hume Kant maintains that we can have knowledge which is both Unlike Hume Kant maintains that we can have knowledge which is both informative and certain: informative and certain:

Synthetic a priori knowledgeSynthetic a priori knowledge

Such knowledge is universal and necessarySuch knowledge is universal and necessary

Without it experience would not be possibleWithout it experience would not be possible

Kant’s Copernican revolution makes humans, not the world, the central Kant’s Copernican revolution makes humans, not the world, the central focus of epistemologyfocus of epistemology

Our minds create the conditions necessary to experience the worldOur minds create the conditions necessary to experience the world

Space and TimeSpace and TimeCategories of the UnderstandingCategories of the Understanding

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CONCLUSION TO TOPIC

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TOPIC CONCLUSION

Rationalists

Plato

Descartes

Chomsky

Empiricists

Aristotle

Aquinas

Locke

Hume

Kant’s Transcendental

Idealism


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