LECTURE 14: HUME’S RADICAL EMPIRICISM

TODAY’S LECTURE

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

1.1.Recap our investigation into empiricist theories of knowledgeRecap our investigation into empiricist theories of knowledge

2.2.Briefly consider the problem of correspondence and Berkeley’s Briefly consider the problem of correspondence and Berkeley’s arguments against Locke’s theory of knowledgearguments against Locke’s theory of knowledge

3.3.Become introduced to the radical empiricism of David HumeBecome introduced to the radical empiricism of David Hume

4.4.Critique and discuss Hume’s theory of knowledge and its implications Critique and discuss Hume’s theory of knowledge and its implications on philosophy, metaphysics, & science.on philosophy, metaphysics, & science.

RESPONSES TO LOCKE

RESPONSES TO LOCKE

Experience

Sensation Reflection

Simple Ideas

Complex Ideas

Passive

Active

Locke’s Theory of Knowledge

Water itself Idea of the water

The idea of the water The idea of the water corresponds corresponds to a real objectto a real object

MindReality

Epistemological dualism

Inner Experience

External Experience

Water itself

Idea of the water1.

2.3.

RESPONSES TO LOCKE

The Problem of CorrespondenceThe Problem of Correspondence

RepresentationalRepresentational theories of perception maintain that everything we theories of perception maintain that everything we know is an idea in the mind that represents or corresponds to something know is an idea in the mind that represents or corresponds to something

outside of the mindoutside of the mind

Problem:Problem:

How do we know if our ideas of an object accurately correspond to the How do we know if our ideas of an object accurately correspond to the object itself?object itself?

All we have are ideas of objectsAll we have are ideas of objects

We cannot have knowledge of anything that is not an ideaWe cannot have knowledge of anything that is not an idea

Therefore, we cannot have knowledge of an object apart from an ideaTherefore, we cannot have knowledge of an object apart from an idea

Therefore, we can never know if our ideas of water correspond to the Therefore, we can never know if our ideas of water correspond to the water itselfwater itself

Berkeley’s Response to Locke

Water itself Idea of the water

Berkeley argues that there is nothing Berkeley argues that there is nothing more more to an object than the to an object than the qualities we perceive (the idea)qualities we perceive (the idea)

We can never perceive the causes of things we perceiveWe can never perceive the causes of things we perceive

MindReality

Epistemological dualism

Inner Experience

External Experience

Water itself

Idea of the water1.

2.3.

Berkeley’s theory of Reality

Mind

Idea of the water

Ideas exist only in mindsAll things are ideas

Therefore, all things exist only in minds

RESPONSES TO LOCKE

Berkeley’s Arguments for IdealismBerkeley’s Arguments for IdealismEsse est Percepti Esse est Percepti

(To be is to be perceived)(To be is to be perceived)

All objects (chair, water etc.) are sensible thingsAll objects (chair, water etc.) are sensible things

A sensible thing is a collection of qualities that we perceiveA sensible thing is a collection of qualities that we perceive

There is nothing more to any object than the sum of its qualitiesThere is nothing more to any object than the sum of its qualities

All sensible qualities exist only as ideasAll sensible qualities exist only as ideas

Therefore, objects only exist in mindsTherefore, objects only exist in minds

Nothing exists independently of a perceiving mindNothing exists independently of a perceiving mind

The idea of a substratum (substance/matter) that is the cause of ideas, but free from qualities is incoherent. This is because we cannot:

a)have an idea of something that cannot be experiencedb)perceive the causes of what we perceivec)conceive of anything without qualities.

RESPONSES TO LOCKE

In SummaryIn Summary

Locke’s theory of knowledge faces the following problems:Locke’s theory of knowledge faces the following problems:

1.1.The problem of correspondenceThe problem of correspondence

We can never be sure whether our ideas of an object correspond to We can never be sure whether our ideas of an object correspond to the object itselfthe object itself

There is an epistemological gap between our knowledge of an object There is an epistemological gap between our knowledge of an object and the object itselfand the object itself

2.2.Berkeley’s CriticismsBerkeley’s Criticisms

We are never able to have an idea of anything that cannot be We are never able to have an idea of anything that cannot be perceivedperceived

The idea of physical substance is incoherentThe idea of physical substance is incoherent

All that we can be sure of is that minds and ideas in minds existAll that we can be sure of is that minds and ideas in minds exist

We can never have access to the object itselfWe can never have access to the object itself

DAVID HUME

DAVID HUME

David Hume:David Hume:

oLived 1711-1776Lived 1711-1776

oOne of the ‘great’ British empiricistsOne of the ‘great’ British empiricists

oAdvocated a Advocated a Radical Radical form of form of empiricismempiricism

oMade important contributions to Made important contributions to Metaphysics, Epistemology, Philosophy Metaphysics, Epistemology, Philosophy of Religionof Religion

oHume’s radical empiricism has Hume’s radical empiricism has important consequences for the important consequences for the investigation into philosophy, religion investigation into philosophy, religion and scienceand science

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 bases of knowledge:There are two bases 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

What’s so radical about Hume’s radical empiricism?What’s so radical about Hume’s radical empiricism?

Aristotle, Aquinas, & Locke all argue that we can have certain Aristotle, Aquinas, & Locke all argue that we can have certain knowledgeknowledge

For example; For example;

This is a chairThis is a chairThe chair is The chair is really really redredThe chair existsThe chair exists

But! Hume argues that these thinkers fail to follow empiricism to its But! Hume argues that these thinkers fail to follow empiricism to its rationalrational conclusions conclusions

Hume: If all knowledge comes from perceptionHume: If all knowledge comes from perception

EitherEitherOur ideas are certain but not informativeOur ideas are certain but not informative

OrOrOur ideas are informative but not certainOur ideas are informative but not certain

IMPLICATIONS OF HUME’S RADICAL EMPIRICISM

IMPLICATIONS

The limits of knowledge:The limits of knowledge:

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

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

Relations of ideas can give us certain knowledge

They don’t teach us anything new

They have no bearing or relevance on reality

For Example:

Socrates is a manAll men are mortalTherefore Socrates is mortal

Doesn’t teach us anything new

Has no relevance upon reality

Certain

IMPLICATIONS

The limits of knowledge:The limits of knowledge:

2. Matters of Fact2. Matters 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.

Matters of fact can teach us new things about the Matters of fact can teach us new things about the worldworld

But they can never be certainBut they can never be certain

It is always possible that they can be rendered falseIt is always possible that they can be rendered false

Entirely dependent on perceptionsEntirely dependent on perceptionsFor Example:

Earth days are now 1.26 nanoseconds faster

Teaches us something new about the world

Cannot be certain

IMPLICATIONS

Hume’s attack on the principle of substance:Hume’s attack on the principle of substance:

It is natural to It is natural to believebelieve::

Descartes/Locke: There exists both mental and physical substanceDescartes/Locke: There exists both mental and physical substance

Berkeley: Physical substance does not exist but mental substance Berkeley: Physical substance does not exist but mental substance (mind) does(mind) does

Hume’s challenge:Hume’s challenge:

Do we ever perceive substance? No.Do we ever perceive substance? No.

Therefore, we cannot Therefore, we cannot rationally rationally claim that substance existsclaim that substance exists

Hume: Sense impressions have priority over ideasThere are no ideas without sense impressions

IMPLICATIONS

Hume’s attack on the principle of the ‘Self’:Hume’s attack on the principle of the ‘Self’:

It is natural to It is natural to believebelieve::

Berkeley/Locke/Descartes: That there is a thinking Berkeley/Locke/Descartes: That there is a thinking thing, thing, a ‘self’, a ‘self’, ego, etc. ego, etc.

Hume’s challenge:Hume’s challenge:

Do we ever perceive a self? No. Only many perceptionsDo we ever perceive a self? No. Only many perceptions

Therefore, we cannot Therefore, we cannot rationally rationally claim that the self existsclaim that the self exists

Hume: Sense impressions have priority over ideasThere are no ideas without sense impressions

IMPLICATIONS

Hume’s attack on the principle of ‘Causality’:Hume’s attack on the principle of ‘Causality’:

It is natural to It is natural to believebelieve::

That every event has a cause / Causal connectionThat every event has a cause / Causal connection

Hume’s challenge:Hume’s challenge:

Do we ever perceive a necessary connection? No.Do we ever perceive a necessary connection? No.

We perceive that A occurs, then B occurs; We perceive that A occurs, then B occurs; but we don’t perceive the necessary connection where A but we don’t perceive the necessary connection where A causescauses B B

All we perceive is contiguity (things close together) and succession; All we perceive is contiguity (things close together) and succession;

We never perceive causation!We never perceive causation!

Therefore, we cannot Therefore, we cannot rationally rationally claim that every event has a causeclaim that every event has a cause

Hume: Sense impressions have priority over ideasThere are no ideas without sense impressions

IMPLICATIONS

Examples against causation:Examples against causation:

At age 1 a child begins to: At age 1 a child begins to:

oFeed themselvesFeed themselvesoWalk by themselvesWalk by themselvesoLearns simple wordsLearns simple wordsoReceives their Measles, Mumps, Rubella Receives their Measles, Mumps, Rubella vaccinationsvaccinationsFor Example:

A child (A) receives their MMR vaccinations, then (B) begins to feed themselves

A B

But! A did not cause B.

IMPLICATIONS

Implications for modern scientists:Implications for modern scientists:

1.1.All scientific theories must be limited to what can be observed or All scientific theories must be limited to what can be observed or observed in principleobserved in principle

2.2.All scientific claims are eitherAll scientific claims are eitheri.i. Relations of ideasRelations of ideas

E.g. All mammals are warm bloodedE.g. All mammals are warm bloodedOrOr

ii.ii. Matters of factMatters of factE.g. The Earth day is now 1.26 nanoseconds fasterE.g. The Earth day is now 1.26 nanoseconds faster

3.3.Scientific claims/’laws’/theories cannot be certain (only likely or Scientific claims/’laws’/theories cannot be certain (only likely or unlikely)unlikely)

It is always possible that a scientific claim can be proved false It is always possible that a scientific claim can be proved false because of future observationsbecause of future observations

Popper: Scientific theories must be falsifiable (Principle of Falsifiability)

For example: Theories of the subconscious cannot be observed or falsified; therefore they are not scientific

SUMMARY

Summary:Summary:

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 perceptionsAll ideas are derived from perceptions

Any idea we have that is NOT derived from perceptions should be Any idea we have that is NOT derived from perceptions 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)