lecture 15: certainty

LECTURE 15: CERTAINTY

TODAYS LECTUREIn Todays Lecture we will:

Review Humes radical empiricism and its consequences

Outline and investigate Kants theory of knowledge: Transcendental Idealism

Discuss whether Kants theory overcomes Humes radical empiricism

Conclude our investigation into the theory of knowledge

RECAP: DAVID HUME

DAVID HUMEDavid Humes Phenomenalism

All knowledge is derived from and limited to appearances

Appearances are presented to us in our perceptions

Perceptions can be divided between

ImpressionsLively, Vivid Sensations

IdeasPale impressions / copies

All ideas are derived from impressions

All the mind possesses is a collection of perceptions

DAVID HUMEDavid Humes Phenomenalism

There are two types of knowledge:

Relations of IdeasIdeas that are intuitively or demonstratively certain

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

Matters of FactIdeas that pertain to the world

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

DAVID HUMEDavid Humes attack against abstract knowledge

Empirical (all) knowledge can only be either:

Necessarily true but not informativeOrInformative but not certain

All ideas are derived from appearances

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

DAVID HUMEAccording to Hume we must abandon the following abstract concepts:

The concept of causationWe never perceive a necessary cause; only succession and contiguity

The selfWhen we reflect we never find a thinking thing; only many different perceptions

The concept of substanceWe never perceive substance

Furthermore:

All scientific knowledge is informative but not certain

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

KANT

IMMANUEL KANTOutline:

Lived 1724-1804

Represents an important turning point in epistemology

Wrote the Critique of Pure Reason in response to Humes radical empiricism

IMMANUEL KANTPrelude to Kants theory of knowledge:

Kant was heavily influenced by Humes radical empiricism

I openly confess my recollection of David Hume was the very thing which many years ago first interrupted my dogmatic slumber and gave my investigations in the field of speculative philosophy a quite new direction

(Textbook, p.232)

IMMANUEL KANTKant maintains the following:

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

He also rejects the rationalist claim that we possess innate ideas

Unlike Hume Kant claims we can be certain that:

Every event must have a cause

Substance exists

The self exists

KANTS THEORY OF KNOWLEDGE

A Priori

Independent of senses

Universal

CertainA Posteriori

Derived from sense experience

Specific

Not certainKANTS THEORY OF KNOWLEDGEA Priori

Independent of senses

A Posteriori

Derived from sense experience

Analytic

True by definition

No relevance to realitySynthetic

Not logically certainKants understanding of knowledge

KANTS THEORY OF KNOWLEDGEActivity: List any knowledge that corresponds to the following categories:

Synthetic a posteriori KnowledgeThe room is redThe moon is 2159 miles in diameter

Analytic a priori knowledgeAll bachelors are unmarried menA triangle is a three sided closed shape

Analytic a posteriori Knowledge

KANTS THEORY OF KNOWLEDGEThe search for synthetic a priori knowledge

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

It must be both Synthetic and a priori

Informative, not just true by definitionNecessary & UniversalThe big question is whether such knowledge exists!

KANTS THEORY OF KNOWLEDGETraditional theories of knowledge

KANTS THEORY OF KNOWLEDGEKants Copernican Revolution

KANTS THEORY OF KNOWLEDGEKants theory of knowledge

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

SAP is the basis for experience

SAP defines how we experience

Our minds possess innate structures called categories of the understanding

UnityPluralityTotalityRelations of substance and characteristics of substanceRelations of cause and effectRelations of reciprocity

KANTS THEORY OF KNOWLEDGESpace and Time

Space and Time are both a priori conditions for all experience

ALL objects must be in space and time to be experienced

Kant maintains that space and time are contributed by our minds

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

KANTS THEORY OF KNOWLEDGEKants disagreement with Hume:

Hume maintained that belief in the following is irrational:

CausalityThe selfSubstance

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

They are universal and necessary for experience

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

KANTS THEORY OF KNOWLEDGESummary:

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

Such knowledge is universal and necessary

Without it experience would not be possible

Kants Copernican revolution makes humans, not the world, the central focus of epistemology

Our minds create the conditions necessary to experience the world

Space and TimeCategories of the Understanding

CONCLUSION TO TOPIC

TOPIC CONCLUSION

RationalistsPlatoDescartesChomsky

EmpiricistsAristotleAquinasLockeHume