Introduction to Philosophy Course: Descartes and Hume

Six Lectures on the Philosophy of Descartes

Recommended Reading: Text and Commentaries The only Cartesian text you must read for this course is the Meditations on First Philosophy, although the Discourse on Method is also recommended. Both are available together in cheap editions from Hackett and Penguin. These are perfectly acceptable, although students wanting more than just the basics may prefer to buy the Selected Philosophical Writings, ed. John Cottingham (CUP, 1988), which contains more of Descartes' philosophy. Unfortunately, it is also significantly more expensive. You should also make an effort to read at least one of these commentaries, listed in approximate order of ascending difficulty.

1. Tom Sorell, Descartes, Oxford, OUP, 1987. (A Past Masters volume - short, quick, and easy).

2. John Cottingham, Descartes, Oxford, Blackwell, 1986. (Perhaps the best general introduction to D & his ideas).

3. Gary Hatfield, Descartes and the Meditations, London, Routledge, 2003. Excellent new introduction, ideal for students.

4.Margaret Wilson, Descartes, London, Routledge, 1978. (A good commentary, spelling out D's main arguments with great clarity).

5. Anthony Kenny, Descartes. A Study of his Philosophy, Bristol, Thoemmes, 1993. (Exegesis and acute critical commentary)

6. Georges Dicker, Descartes: An Analytical and Historical Introduction, OUP, 1993. Includes the bulk of the text of the Meditations, plus detailed critical analysis of Descartes' arguments).

7. John Cottingham, A Descartes Dictionary, Oxford, Blackwell, 1993. (An invaluable reference work, ideal for looking up key words and phrases in Descartes).

8. Marjorie Grene, Descartes, Harvester, Sussex, 1985. (Good on Descartes' relations with important critics such as Gassendi and Arnauld).

9. Bernard Williams, Descartes. The Project of Pure Enquiry, Penguin, 1978. (A bit of an oddball, this - a major modem philosopher attempting a reconstruction of Descartes in a modem 'analytic' idiom. Worth the effort, but by no means easy).

10. John Cottingham, ed, The Cambridge Companion to Descartes, CUP, 1992. (Good collection of overview articles on various aspects of D's philosophy).

11. Amelie Rorty, ed, Essays on Descartes' Meditations, University of California Press, 1986. (Excellent collection of articles, but not really for the beginner).

12. Harry Frankfurt Demons, Dreamers, and Madmen, Indianapolis, 1970. (Fascinating, and great fun, but not really a work for the beginner).

13. Peter Markie, Descartes' Gambit, Cornell, 1986. (Interesting defence of some of Descartes' moves linking epistemology to metaphysics).

14. Edwin Curley, Descartes Against the Sceptics, Harvard Press, 1978. (Scholarly treatment of Descartes' relation to scepticism).

Lecture 1: Argument Outline

The Sceptic's Argument:

PI. Knowledge requires certainty (= the right to be sure).

P2. We can never attain certainty about anything.

C. We know nothing.

Some modem epistemologists reject P1; Descartes accepts Pl, so to evade the sceptic's conclusion C he must reject P2. Why do the sceptics accept P2? Pyrrhonian argument:

P3. Unless there is a criterion of truth, nothing is certain

P4. There is no criterion of truth

C. Nothing is certain (=P2 in the above argument).

For Descartes to deny C here he must deny either P3 or P4. But he accepts P3. So to avoid scepticism he must deny P4 and assert the existence of a criterion of truth.

Descartes' argument in Meditation One:

All my beliefs are derived from Sense, Authority, or Reason. Beliefs derived from Sense, Authority, and Reason might be false. Therefore, all my beliefs might be false.

Can you spot the equivocation here? Strong version: It is possible that all my beliefs (taken collectively) are false, i.e. that I have not one single true belief. Weak version: It is possible that any one of my beliefs (taken individually) might be false, i.e. that I can't be absolutely sure of any of them.

The strong version may turn out to be incoherent. But does D need it for his argument? Perhaps not. Cf Williams on the red and green mushrooms. The rule of methodological doubt is to treat every doubtful proposition as if it were known to be false. Levels of doubt in Meditation 1: Illusions - Dreams - the Demon. The crucial sceptical claim is that I couldn't tell if I were being deceived by the demon. Thus:

P5. I can't know that I am, e.g. seeing a chair if exactly the same visual experience could be produced by the demon.

P6. Any visual (auditory, etc) experience could be produced by the demon.

C. My senses cannot provide me with any knowledge of the external world (if it exists).

Lecture 2: Argument Outline

Is there any belief of mine that couldn't be false? Yes, the belief that I exist. 'I don't exist' is self-defeating: there are no conditions under which it could be truly thought or asserted. It gives rise to a pragmatic paradox. Cf 'I'm not here now'. To try to think or assert my own non-existence leads inevitably to the thought that I must exist in order to have the thought. I thus know my own existence - but only as a thinking being. Cogito ergo sum. Is this an ordinary logical inference, thus: I think; but whatever thinks, exists; Therefore I exist?

Or is the cogito an enthymeme? Or (Hintikka) is the relation of cogito to sum the relation of process to product not of premise to conclusion? Why not ambulo ergo sum? The inference looks equally valid, but the premise is uncertain. I can doubt that I walk but not that I think. Phantom limbs. It follows that the mind is better known than the body. I know myself as a res cogitans (thinking being) while remaining uncertain whether I am also an embodied being. The role(s) played by the cogito in the Meditations:

1. It refutes scepticism by providing an example of certainty.

2. It provides the criterion of truth.

3. It establishes that the mind is better known than the body.

Here 1 contradicts the sceptic's P2, 2 contradicts the sceptic's P4 (see last week's sheet). 3 provides a crucial premise for Descartes' dualism (to come).

How does the cogito prove the existence of a criterion of truth? Answer:

4. Unless there is a criterion of truth, nothing is certain.

5. It is false that nothing is certain.

C. Therefore, there is a criterion of truth.

By the end of Meditation Two D will claim to have made real progress. He now claims to know the contents of his own mind with absolute certainty. The world remains a problem.

Lecture 3: Argument Outline.

Why does D try to prove the existence of God? Well, how else can he get back to the world? Crucial first premise for both Descartes' arguments for the existence of God (Meds 3 & 5).

P1. I have an idea of God (=df Being with all perfections). Trademark argument (Med 3). Phase One:

P2. All ideas are either innate, sensory, or artificial.

P3. The idea of God is not sensory (obvious).

P4. The idea of God is not artificial (needs support)

C. The idea of God is innate.

Trademark argument: Phase Two:

PI. I have an innate idea of God.

P2. Whatever exists has an adequate cause

P3. The only possible cause for my idea of God is God.

C. God exists.

Here P2 violates the principle of doubt, and P3 needs further support. D introduces his distinction between 'objective' and 'formal' reality. The objective reality of an idea (picture) is its representational content, what it is an idea of. D's claim is that the content of our idea of God needs explanation, and that we couldn't have dreamed God up for ourselves. Analogy: the child with the plan (idea) of a super-computer (See Cottingham).

Ontological argument (Med 5):

PI. God =df Being with all perfections

P2. Existence is a perfection.

C. God exists.

This is a purely analytic argument, quite different from the causal argument of Med 3.On this view, 'God exists' is like 'bachelors are unmarried' or 'triangles have three sides', i.e. simply involves spelling out the meaning of the term.

Objection (Gassendi, Kant, Russell): Existence is not a predicate of objects, therefore not a perfection. Grammar misleads us here. 'God exists' is grammatically akin to 'God cares', but its proper logical form is quite different. To see this, contrast the negations 'God doesn't exist' and 'God doesn't care'. The atheist's claim is that the set of divine beings is empty. Frege: existence is a second-order predicate (of sets or properties), not a first-order predicate (of objects).

Lecture 4: Argument Outline

The existence of God (all-powerful and benevolent) excludes that of the Cartesian demon (all-powerful and malevolent). God, says D, provides a guarantee of our clear and distinct ideas and thus a justification of the criterion of truth. Argument:

P1. If I had no criterion of truth, I could never know that any of my beliefs is true.

P2. But I do know (from the cogito) that some of my beliefs are true.

Cl. Therefore I have a criterion of truth.

P4. But what is special about the cogito is just that it is clear and distinct (c&d).

C2. Therefore, whatever I perceive c&d is true.

There is now a problem of error. If I have my faculties from a benevolent and trustworthy God, how can I fall into error at all? D answers (Med 4) that my errors arise from the abuse of my free will, giving assent to what is not c&d perceived. I am potentially infallible (not of course omniscient).

Problem 1. Is whether a perception is c&d something introspectible? A dilemma arises here: 'Yes' faces counterexamples, e.g. conflicting intuitions and intuitive judgments that turned out to be false. (Lots of examples in the history of mathematics). 'No' leads to the need for a new criterion for what is c&d. A regress looms.

Problem 2. The 'Cartesian Circle' (Amauld).

Descartes uses Reason (reliance on c&d ideas, logic) to prove the existence of God. But he needs God to justify our reliance on c&d ideas. So he is guilty of a vicious circle, using A to prove B and B to prove A. Three attempts to escape the 'vicious circle' objection:

1. Drop the reference to objective truth and argue only for the internal coherence of a set of indubitable beliefs (Frankfurt). 2. Emphasise the role of the time factor (Gilson, Doney).

3. Deny that the circle is a vicious one (Williams).

Lecture 5: Argument Outline

Whatever I perceive c&d is true. I have a c&d intellectual grasp of the essence of material substance ('something extended, flexible, and moveable'). Cf the wax in Med 2. This c&d idea of matter is an innate idea of the intellect, not an idea of the senses. The senses can't tell me it is the same wax that remains when all its sensible properties change.

But does anything exist corresponding to this idea? Not necessarily. Its essence does not entail existence. How then can we prove the existence of bodies? By a causal argument:

P1. I experience sensory states which I spontaneously take to be perceptions of bodies.

P2. These sensory states must have adequate causes.

P3. I am not myself the cause of these sensory states. They are not subject to my will.

P4. Other possible causes include God, angels, demons …

P5. But God (who is trustworthy) has given me a strong natural inclination to believe that these sensory states are caused by bodies. C. Therefore, bodies exist and cause my perceptions of them.

An alternative reconstruction would run as follows, invoking the doctrine of Med 4:

P1. God has given me the means to correct all my errors.

P2. But everything in my experience is as if there were a world of bodies.

P3 I have a strong inclination to believe in bodies.

Cl. So (from P2 and P3) if there were no external world, God would have made me subject to an error I could not correct.

C2 So (from P1 and Cl) there is an external world.

But God's guarantee extends only to our c&d ideas (size, shape, motion). not to our confused ideas (colour, heat, etc). These latter are mere sensations.

Lecture 6: Argument Outline

To prove that A is distinct from B. one must show that A and B have different properties. If A has a property B lacks, or vice versa, then A is not = B. D offers three lines of argument for his conclusion that I (=my mind) am distinct from my body.

A1. The argument from doubt.

PI. My existence is not doubtful.

P2. The existence of my body is doubtful.

C. Therefore, I am not my body.

Is this valid? No. Even if one grants the two premises, the conclusion doesn't follow. To see this, construct a parallel case by way of counterexample:

PI. I can doubt that √289 > 16.

P2. I cannot doubt that 17 > 16.

C Therefore, √289 ≠17.

The premises are true; the conclusion is false. So the argument is invalid. Then so too is Descartes' version. Why? Because clauses governed by psychological verbs ('A doubts that…') are intensional and not extensional. (Cf ‘Lois Lane loves Superman’).

A2. The argument from c&d ideas.

PI. I have clear, and distinct ideas of mind and body.

P2. Whatever can be conceived distinctly can exist separately.

C Therefore, mind and body are really distinct and only contingently connected.

But (Arnauld) is the supposedly c&d idea of mind an adequate idea, or only an abstraction? Might I not be necessarily embodied, but not obviously so? And can we really make sense of the notion of disembodied existence?

A3. The argument from indivisibility.

PI. My body is (infinitely) divisible.

P2. I (=my mind) am indivisible. The very notion of half a mind is nonsense.

C. I am not my body.

A materialist response: 'mind' is a mere label for certain powers of complex bodies. These powers might be indivisible in the sense of being all-or-nothing.

Problems for Descartes' dualism:

1. Mind -Body interaction becomes unintelligible. 2. Embodiment and bodily sensations. 'I am not in my body like a pilot in a boat'.

Six Lectures on the Philosophy of Hume

Recommended Reading: Text and Commentaries. The only primary text you must read for this course is Hume’s Enquiry Concerning Human Understanding of 1748 (otherwise known as the first Enquiry), although I shall also refer at times to parts of the Treatise of HumanNature (1739-40) and the Dialogues Concerning Natural Religion, published posthumously in 1779. The best edition of the first Enquiry for students is that of Tom Beauchamp (OUP, 1999). The older edition of Selby-Bigge (Clarendon, Oxford, numerous editions) is still serviceable, but Beauchamp has a useful introduction, a helpful and up-to-date bibliography, and a glossary and notes for students struggling with Hume's somewhat archaic English. You should also make an effort to read at least one of the following commentaries, listed as usual in approximate order of ascending difficulty.

1. A.J.Ayer, Hume, OUP, 1980. (A Past Masters volume - quick and easy. Much of Ayer’s philosophy can be traced back to Hume).

2. Alan Bailey and Dan O’Brien, Hume’s Enquiry Concerning Human Understanding: A Reader’s Guide, London, Continuum, 2006 (Introductory work designed for students.)

3. Terence Penelhum, David Hume: An Introduction to his Philosophical System, Indiana, 1992. (Valuable introduction to Hume’s philosophy).

4. G. Dicker, Hume’s Epistemology and Metaphysics: An Introduction, Routledge, London, 1998. (Excellent new book, covering exactly the right ground for this course).

5. Norman Kemp Smith, The Philosophy of David Hume, MacMillan, London, 1949. (An old book, but still worth reading, by one of the great historians of philosophy).

6. Stephen Buckle, Hume's Enlightenment Tract, OUP Oxford 2001. (Best study of the first Enquiry for many years).

7. John Passmore, Hume’s Intentions, 3rd edition, Duckworth, London, 1980. (Distinguishes the ‘naturalistic’ and ‘sceptical’ strains in Hume’s philosophy).

8. Peter Millican, ed, Reading Hume on Human Understanding, OUP, 2002. Superb collection of recent work on the first Enquiry, with a fine bibliography and associated website.

9. David Fate Norton, ed, The Cambridge Companion to Hume, CUP, 1993. (Useful collection of overview articles, plus excellent bibliography).

10. Anthony Flew, Hume’s Philosophy of Belief, London, RKP, 1961. (Close study of the first Enquiry, focussing on Hume’s theory of belief).

11. Barry Stroud, Hume, Routledge, London, 1977. (Major study of Hume by an important modern philosopher, but not always easy).

12. Galen Strawson, The Secret Connexion: Causation, Realism, and David Hume, Clarendon, Oxford, 1989. (The best case for interpreting Hume as a sceptical realist about causation rather than a strict meaning empiricist).

13. Jonathan Bennett, Learning from S ix Philosophers, 2 Volumes, OUP, 2001. (Better on Hume than on Locke, with some insightful remarks on meaning-empiricism).

14. Don Garrett, Cognition and Commitment in Hume's Philosophy, OUP 1997. (Close study of Hume's account of our cognitive powers - sense, memory, imagination, reason - and their respective roles in cognition & belief).

The website at the University of Leeds ( gives access both to the complete text of the first Enquiry and to an extensive bibliography.

Lecture 1 (Hume’s Problem and Project): Argument Outline

Read: Enquiry, Section 2, ‘Of the Origin of Ideas’ and Section 3, ‘Of the Association of Ideas’. Hume’s problem: the dependence of Reason (and hence of Philosophy) on Human Nature. Hume’s project: to be ‘The Newton of the Intellect’.

Hume’s theory of impressions and ideas leads (in the view of many commentators) to meaning-empiricism (Flew, Bennett). This entails that much traditional philosophy is literally nonsense (cf the logical positivists of C20). This 'positivist' reading of Hume was dominant until late C20, when it was challenged by “the New Hume” of the sceptical realist interpretation (Galen Strawson, John Wright, Edward Craig).

Hume's Copy Principle: no (simple) idea without a corresponding impression. Hume’s challenge: find a counter-example! The missing shade of blue. Why doesn’t Hume take it seriously? Could you come up with other counter-examples, that is, concepts not derived from impressions?

The association of ideas is to psychology what Newton’s law of universal gravitation is to physics: experience tells us that it is true, but we do not (cannot?) understand why it is true. Association works by (a) resemblance (b) contiguity © cause & effect. Hume’s fork: ‘relations of ideas’ versus ‘matters of fact’. Only the former can be known a priori. Has Hume condemned his own books to the flames? What room is left for philosophy?

Two possible answers: either (1) philosophy as a purely analytic discipline (conceptual analysis) or (2) philosophical anthropology (naturalism).

Lecture 2 (Induction): Argument Outline

Reading: Enquiry, Section 4, ‘Sceptical Doubts concerning the Operations of the Understanding’ & Section 5, ‘Sceptical Solution of those Doubts.’

‘Induction’ has a broad and a narrow sense. In the broad sense, an argument can be called inductive if it is non-deductive; in the narrow sense, an argument is called inductive if it is a generalization from experience (cf “all swans are white”). Reliance on induction (narrow sense) is fundamental alike to common sense and to science. But what reason can we give why unobserved cases will resemble observed ones? None, says Hume. Referring to Science won’t help because (of course) Science relies on the very assumption under question.

Russell’s chicken (in Problems of Philosophy) & its lesson: we may be in the position of the chicken!

Normative versus Naturalistic approaches to epistemology. Hume can be seen as a precursor of modern naturalism. Hume’s naturalistic response to inductive scepticism. On a naturalistic account, norms regulating belief are derived from the proper functioning of our belief-forming mechanisms. There is no higher court of appeal, and Cartesian doubts do not (cannot?) arise.

According to Hume, “Nature, by an absolute and uncontrollable necessity, has determined me to judge as well as to breathe and feel.” If this is true, we can’t take inductive scepticism seriously. So (assuming that ‘ought implies can’) we are not obliged to take it seriously. If ought implies can, cannot implies is not obliged to. Nature is (fortunately) too strong for Reason.

Can we say that inductive conclusions are probable, given their premises? This looks promising, but turns out to raise a host of further difficulties, some of which Hume saw (see Treatise, Appendix). Subjective probability (=degree of belief) vs objective probability. To make progress we clearly need an objective notion of probability.

Classical mathematical theory of probability is fine but inapplicable to the problem of induction. Empirical (frequency) theory of probability is question-begging, therefore no solution at all. Rudolf Carnap et al tried to develop a ‘logical’ theory of probability as partial entailment. But this promising programme led to one paradox after another.

Lecture 3 (Causation): Argument Outline

Reading: Enquiry, Section 7, ‘Of the Idea of Necessary Connection’.

In his discussion of causation, Hume attempts to do three things:

1. To spell out or articulate our naïve, pre-reflective notion of cause.

2. To criticize that notion from an empiricist viewpoint.

3. To replace the naïve notion with a better one, i.e. one with proper empirical credentials. You need to understand this complex aim if you are to make sense of his argument.

The naïve notion of cause contains three elements:

1. If C causes E, C and E are contiguous in space.

2. If C causes E, C precedes E in time.

3. If C causes E, there is a necessary connection between C and E.

Hume accepts 1 and 2, but challenges the meaning of clause 3. Whence, he asks, this (supposed) idea of necessary connection? From what impression could it be derived? My senses tell me that C precedes E and is contiguous with E, but not that, given C, E must occur. To say that C “makes E happen” or has a “power” to produce E seems equally unintelligible.

All that experience teaches is that events of kind C regularly precede events of kind E. So perhaps we should delete clause (3) above and replace it by (4).

4. Events of kind C regularly precede events of kind E.

This, says Hume, is OK as far as it goes, but it can’t be the whole story. We still need to explain our sense of causal necessity, our feeling that the glass must break when dropped on the concrete floor. This ‘must’, Hume explains, is in the mind of the perceiver, i.e. is a merely subjective ‘must’. Regular succession generates in the minds of observers (by the psychological laws of association of ideas) an expectation of a certain outcome. This expectation is itself a new impression (of reflection, not of sense), hence the original from which a new idea can be copied. So we add a further clause:

5. Any experiencer aware of the regularity with which Cs are followed by Es will come to expect an E the next time he or she experiences a C.

The regularity is objective, the expectation (and hence the sense of ‘must’) is subjective. Hence the two definitions of cause in the Enquiry: the first = (1) + (2) + (4); the second = (1) + (2) + (5). The two definitions are clearly intended to be complementary rather than competitors. The first definition gives the objective side/aspect of causation; the second gives its subjective side/aspect.

Hume also offers a further definition of cause in counterfactual terms (what would have happened if….) He thinks this is equivalent to the definitions he has already given. But he’s wrong about this. Counterfactuals raise deep difficulties for empiricist accounts of knowledge. We can observe what does actually happen, but not what would have happened.

Lecture 4 (Liberty and Necessity): Argument Outline

Reading: Enquiry, Section 8, ‘Of Liberty and Necessity’.

The old problem of freewill vs determinism: we seem strongly inclined to believe both, but many philosophers have claimed that they are incompatible. When I performed action A, could I have performed action B instead? Freewill → “Yes”; Determinism → “No”; Therefore freewill and determinism are incompatible. This is the central argument of the incompatibilists, who then divide into two groups depending on which of the two theses they reject.

Hume is the most important advocate of compatibilism, the belief that, properly construed, our belief in universal determinism is perfectly compatible with our belief in free agency. The whole dispute, he thinks, is due to misunderstandings and muddles, and can be resolved by a few clear definitions. All men, he claims, “have ever agreed in the doctrine both of necessity and of liberty, according to any reasonable sense, which can be put on those terms.”

The “doctrine of necessity” = universal determinism = the claim that every event falls under universal laws. All men believe this, says Hume, BOTH for the events of inanimate nature AND for human actions. Cf the prisoner and his jailer, the man who leaves his purse of gold at Charing Cross, the shopper going to market…. Where we come across counter-examples to universal claims, we assume the “secret operation of contrary causes” rather than accept genuine indeterminism. Human actions stem from human character – if they did not, morality itself would collapse. So it turns out that moral responsibility presupposes determinism, and cannot therefore be incompatible with it.

As for free agency, all we can mean by it is “a power of acting or not acting, according to the determinations of the will”, which power “is universally allowed to belong to every one who is not a prisoner and in chains.” To say “I was free to do B” means only “I would have done B if I had so chosen”. But of course my choice was determined by my character and (perceived) situation. This psychological determinism, Hume thinks, poses no threat to our sense of free agency.

Problem (1): Is Hume’s account of free agency adequate? What of the victim of hypnotism or brainwashing, the drug addict or compulsive gambler?

Problem (2): Is God to blame for all our wrong actions? He, after all, must have initiated all the deterministic causal chains. Hume thinks that once again, Nature is too strong for Reason: we do feel moral sentiments, and hence make judgments of praise and blame. This is our natural response to the perceived characters of our fellow humans, and this natural response cannot be eliminated by philosophical reasoning.

Lecture 5 (Miracles): Argument Outline.

Reading: Enquiry Section 10, ‘Of Miracles’ and Section 11, ‘Of a Particular Providence and of a Future State’ Natural & Revealed Religion. S10 of the Enquiry seeks to undermine belief in revealed religion; S11 (and the posthumously published Dialogues concerning Natural Religion) undermine natural religion.

What grounds are given for the belief that someone has revealed knowledge of God and His designs for humans? Miracles and prophecies. Hume asks when it would be rational to believe reports of a miracle (rather than to believe that the supposed witnesses lied, or misunderstood what they saw). His simple answer is “never”. Reasons for doubt are the usual reasons that would be taken into account by historians & lawyers – time-lapse, bias, credulity, and the intrinsic improbability of what is reported. All these factors tell against the Scriptural miracles. Hume’s conclusion: “Our most holy religion is founded on Faith, not on reason”, and (with delicious irony) “whoever is moved by Faith to assent to it, is conscious of a continued miracle in his own person, which subverts all the principles of his understanding….”

What if we today were to see (under controlled conditions) water turning to wine, or a man walking on water? Would we have to reject the testimony of our own senses? Not necessarily. We might say that we had previously got the laws of Nature wrong. In S11 Hume has “a friend” present a speech by an Epicurean philosopher defending the freedom of speech and the claim that the State has no business to suppress certain anti-religious opinions. (The Epicureans accepted the existence of the gods, but denied Creation, Providence, and the immortality of the human soul). Christians argued that Epicureans must be bad men and bad citizens. Why? Because they don’t accept an afterlife, with rewards & punishments.

Hume’s crucial argument: we cannot infer more reality (intelligence, moral perfection, etc) in the unseen cause (God) than is present in the seen effect (the world). So if the world shows some signs of distributive justice (the virtuous usually do better than the wicked) we have a purely natural motive for righteousness; if they do not, we have no warrant for assuming the gods care about justice and will rectify injustices in an afterlife.

Stock Christian claim: our world exhibits limited or imperfect distributive justice – the afterlife will compensate those who suffer unjustly, and punish those who profited from injustice.

Hume’s response: such an inference is permissible for human artefacts (eg incomplete buildings) but only because there is a well-founded generalisation to draw on concerning human beings & their activities (cf his analysis of causality). But the universe is a one-off effect, so gives no warrant for any further inferences regarding its cause. The Dialogues present Hume’s final and definitive treatment of the argument to design.

Lecture 6 (Scepticism): Argument Outline.

Reading: Enquiry, S12, ‘Of the Academical or Sceptical Philosophy’. Hume is a sort of “academic” sceptic (Cicero) not a “Pyrrhonian” sceptic (Sextus Empiricus) Scepticism = the denial of knowledge-claims; it is not, of itself, a positive thesis. The sceptic comes up with alternative possibilities. He says to his opponent the dogmatist “You claim to know that p. But how do you know that q is not the case?” Here q is not put forward as a positive claim, but as a ‘sceptical possibility’ that needs, somehow, to be eliminated if anyone is to claim to know p.

Hume distinguishes antecedent scepticism (= Cartesian methodological doubt, prior to enquiry) from consequent scepticism (concluding from one’s studies that human faculties are hopeless as guides to truth). A modicum of antecedent scepticism, he thinks, is useful (helps us to overcome prejudices) but IF it could ever be universal, such doubts would be incurable. Fortunately, universal antecedent scepticism is quite impossible for us.

The main target of consequent scepticism = beliefs derived from the senses. The standard arguments from illusion don’t impress Hume much: such “trite topics”, he says, serve only as warnings not to trust everything revealed by sense, and to make certain corrections. There are, however, “more profound arguments against the senses, which admit not of so easy a solution.” Belief in an external world, a world of objects that exist independently of my perceptions of them (tables & chairs, trees & houses) is, Hume thinks, a natural belief of mankind, the result of “a natural instinct or prepossession”. (In the Treatise, he gives a detailed psychological mechanism explaining the origin of the belief). Our natural tendency, he continues, is to assume that the immediate objects of our perception = tables & chairs, trees & houses. This is direct or naïve realism, “the universal and primary opinion of all men”.

But this direct or naïve realism is false, “soon destroyed by the slightest philosophy”. The direct or immediate objects of our perceptions are mind-dependent; external objects are assumed to be mind-independent. So the realist shifts from direct to indirect (representative) realism: what I am directly or immediately aware of = the image of the tree in my mind; this image is caused by, and is a representation of, the real tree.

But indirect or representative realism leaves itself wide open to obvious sceptical doubts. By what right do I claim to know anything about the external object (not an object of experience) from the idea or image in my mind? How could I know that the former is the cause of the latter? Facts about causes are learned from experience, but the (supposed) external object is not an object of experience.

The indirect realist (Locke) thinks that colours, etc are mere sensations (only in the minds of observers, not in the world at all) but that size, shape, and motion are objective properties of bodies. But there seems no good reason to accept this distinction and this claim. Why not go all the way with Berkeley, and accept idealism (all that exists = minds and their ideas)? Berkeley’s arguments, says Hume, “admit of no answer and produce no conviction.” As philosophers, we might follow the arguments to Berkeleyan conclusions, and not know where we have gone wrong; but as human beings (and especially as agents) we can’t help believing in a mind-independent world. “Nature is always too strong for principle.”

We thus find ourselves in a “whimsical condition”, with certain natural beliefs which we can NEITHER justify by philosophical reasoning, NOR abandon as unwarranted. These beliefs include those in a mind-independent world of bodies, in induction, and in moral responsibility…

Essay Topics

Descartes 1. In what sense, if any, can Descartes be described as a sceptic?

2. In what sense (if any) is it true that I know my mind better than my body? What does your answer imply regarding the natures of mind and body?

3. Why is it so important to Descartes that he is responsible for his mistakes? Is he right to think that believing something involves an act of assent?

4. Critically discuss ONE of Descartes’ arguments for the existence of God.

5. Is there a vicious circle in the argument of the Meditations?

6. Can you make any sense of the notion that you might continue to exist in a disembodied state? Hume

1. Why does Hume dismiss the “missing shade of blue” as not posing a real threat to his theory of impressions and ideas? What should he have said about it?

2. If I say “It is highly probable that it will rain in Bristol this month”, what sort of claim am I making, and what evidence would I cite to support it? Does such evidence show that Hume was wrong to have doubts about the rationality of induction?

3. Why is Hume’s third definition of cause (in counterfactual terms) not equivalent to his first and second definitions? Why are counterfactuals a problem for empiricists?

4. Did Hume succeed in his “reconciling project”, i.e. his attempt to show that our beliefs in determinism and in free agency are perfectly compatible?

5. How might a defender of miracles have replied to Hume’s critique of the rationality of such a belief?

6. Critically discuss Hume’s views about the rationality of our belief in a mind-independent external world. Is there no way of formulating such a belief in a way that resists sceptical doubts?


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