Lecture 15: Certainty
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Transcript of Lecture 15: Certainty
LECTURE 15: CERTAINTY
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
RECAP: DAVID HUME
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
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.
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)
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
KANT
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
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)
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
KANT’S THEORY OF KNOWLEDGE
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’
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!
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!
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
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
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
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
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
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
CONCLUSION TO TOPIC
TOPIC CONCLUSION
Rationalists
Plato
Descartes
Chomsky
Empiricists
Aristotle
Aquinas
Locke
Hume
Kant’s Transcendental
Idealism