Lecture 14: Hume’s Radical Empiricism

1. Lecture 14: Hume’s Radical Empiricism

2. In Today’s Lecture we will: Recap our investigation into empiricist theories of knowledge Briefly consider the problem of correspondence and Berkeley’s arguments against Locke’s theory of knowledge Become introduced to the radical empiricism of David Hume Critique and discuss Hume’s theory of knowledge and its implications on philosophy, metaphysics, & science. Today’s Lecture

3. Responses to Locke

4. Locke’s Theory of Knowledge: • All ideas (knowledge) comes from experience • There are two forms of experience: • Sensation (Outer) • Reflection (Inner) • All ideas are either from inner experience or outer experience • There are no innate ideas, only innate faculties Responses to Locke Experience Sensation Reflection Simple Ideas Complex Ideas Passive Active

5. Locke’s Theory of Knowledge Idea of the water Water itself Reality Mind The idea of the water corresponds to a real object

6. Epistemological dualism Idea of the water Inner Experience External Experience 1. 3. 2. Water itself

7. The Problem of Correspondence Representational theories of perception maintain that everything we know is an idea in the mind that represents or corresponds to something outside of the mind Problem: How do we know if our ideas of an object accurately correspond to the object itself? All we have are ideas of objects We cannot have knowledge of anything that is not an idea Therefore, we cannot have knowledge of an object apart from an idea Therefore, we can never know if our ideas of water correspond to the water itself Responses to Locke

8. Berkeley’s Response to Locke Idea of the water Water itself Reality Mind Berkeley argues that there is nothing more to an object than the qualities we perceive (the idea) We can never perceive the causes of things we perceive

9. Epistemological dualism Idea of the water Inner Experience External Experience 1. 3. 2. Water itself

10. Berkeley’s theory of Reality Idea of the water Ideas exist only in minds All things are ideas Therefore, all things exist only in minds Mind

11. Berkeley’s Arguments for Idealism EsseestPercepti(To be is to be perceived) All objects (chair, water etc.) are sensible things A sensible thing is a collection of qualities that we perceive There is nothing more to any object than the sum of its qualities All sensible qualities exist only as ideas Therefore, objects only exist in minds Nothing exists independently of a perceiving mind Responses to Locke The idea of a substratum (substance/matter) that is the cause of ideas, but free from qualities is incoherent. This is because we cannot: have an idea of something that cannot be experienced perceive the causes of what we perceive conceive of anything without qualities.

12. In Summary • Locke’s theory of knowledge faces the following problems: • The problem of correspondence • We can never be sure whether our ideas of an object correspond to the object itself • There is an epistemological gap between our knowledge of an object and the object itself • Berkeley’s Criticisms • We are never able to have an idea of anything that cannot be perceived • The idea of physical substance is incoherent • All that we can be sure of is that minds and ideas in minds exist • We can never have access to the object itself Responses to Locke

13. David Hume

14. David Hume • David Hume: • Lived 1711-1776 • One of the ‘great’ British empiricists • Advocated a Radical form of empiricism • Made important contributions to Metaphysics, Epistemology, Philosophy of Religion • Hume’s radical empiricism has important consequences for the investigation into philosophy, religion and science

15. David Hume • David Hume’s Phenomenalism • All knowledge is derived from and limited to appearances • Appearances are presented to us in our perceptions • Perceptions can be divided between • Impressions • Lively, Vivid Sensations • Ideas • Pale impressions / copies • All ideas are derived from impressions • All the mind possesses is a collection of perceptions

16. David Hume • David Hume’s Phenomenalism • There are two bases of knowledge: • Relations of Ideas • Ideas that are intuitively or demonstratively certain • E.g. Geometry, Arithmatic, Logic, Algebra etc. • Matters of Fact • Ideas that pertain to the world • E.g. The sun will rise tomorrow, This chair is red, etc.

17. What’s so radical about Hume’s radical empiricism? • Aristotle, Aquinas, & Locke all argue that we can have certain knowledge • For example; • This is a chair • The chair is really red • The chair exists • But! Hume argues that these thinkers fail to follow empiricism to its rational conclusions • Hume: If all knowledge comes from perception • Either • Our ideas are certain but not informative • Or • Our ideas are informative but not certain David Hume

18. Implications of Hume’s Radical Empiricism

19. The limits of knowledge: • Relations of Ideas • Ideas that are intuitively or demonstratively certain • E.g. Geometry, Arithmetic, Logic, Algebra etc. Implications 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 man All men are mortal Therefore Socrates is mortal Doesn’t teach us anything new Has no relevance upon reality Certain

20. The limits of knowledge: • 2. Matters of Fact • Ideas that pertain to the world • E.g. The sun will rise tomorrow, This chair is red, etc. Implications Matters of fact can teach us new things about the world But they can never be certain It is always possible that they can be rendered false Entirely dependent on perceptions For Example: Earth days are now 1.26 nanoseconds faster Teaches us something new about the world Cannot be certain

21. Hume: Sense impressions have priority over ideas • There are no ideas without sense impressions Implications • Hume’s attack on the principle of substance: • It is natural to believe: • Descartes/Locke: There exists both mental and physical substance • Berkeley: Physical substance does not exist but mental substance (mind) does • Hume’s challenge: • Do we ever perceive substance? No. • Therefore, we cannot rationally claim that substance exists

22. Hume: Sense impressions have priority over ideas • There are no ideas without sense impressions Implications • Hume’s attack on the principle of the ‘Self’: • It is natural to believe: • Berkeley/Locke/Descartes: That there is a thinking thing, a ‘self’, ego, etc. • Hume’s challenge: • Do we ever perceive a self? No. Only many perceptions • Therefore, we cannot rationally claim that the self exists

23. Hume: Sense impressions have priority over ideas • There are no ideas without sense impressions Implications • Hume’s attack on the principle of ‘Causality’: • It is natural to believe: • That every event has a cause / Causal connection • Hume’s challenge: • Do we ever perceive a necessary connection? No. • We perceive that A occurs, then B occurs; • but we don’t perceive the necessary connection where A causes B • All we perceive is contiguity (things close together) and succession; • We never perceive causation! • Therefore, we cannot rationally claim that every event has a cause

24. Examples against causation: • At age 1 a child begins to: • Feed themselves • Walk by themselves • Learns simple words • Receives their Measles, Mumps, Rubella vaccinations Implications For Example: A child (A) receives their MMR vaccinations, then (B) begins to feed themselves A B But! A did not cause B.

25. Implications for modern scientists: • All scientific theories must be limited to what can be observed or observed in principle • All scientific claims are either • Relations of ideas • E.g. All mammals are warm blooded • Or • Matters of fact • E.g. The Earth day is now 1.26 nanoseconds faster • Scientific claims/’laws’/theories cannot be certain (only likely or unlikely) • It is always possible that a scientific claim can be proved false because of future observations Implications 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

26. Summary: Empirical (all) knowledge can only be either: Necessarily true but not informative Or Informative but not certain All ideas are derived from perceptions Any idea we have that is NOT derived from perceptions should be abandoned Summary 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)