Hume’s Epistemology

1. Hume’s Epistemology Melchert, Norman. “Unmasking the Pretensions of Reason” The Great Conversation: A Historical Introduction to Philosophy. Second edition. California: Mayfield Publishing Company, 1995: 346 – 375.

2. The Theory of Ideas • What are Ideas? And how do we come to have them? • Hume uses “perceptions” as a general term for “all the contents of the mind.” • PERCEPTIONS: Divided into 2 major classes • IMPRESSIONS • IDEAS

3. Impressions and Ideas • “The difference betwixt these consists in the degrees of FORCE and LIVELINESS with which they strike upon the mind, and make their way into our thought or consciousness.” • IMPRESSION: • Those perceptions which enter with most force and violence. • They refer to all our sensations, passions and emotions, as they make their first appearance in the soul. • IDEAS: • The faint images of these in thinking and reasoning.

4. IMPRESSIONS AND IDEAS: SIMPLE AND COMPLEX • The impression you have when you slap the table is simple. • The impression you have when you hear a melody is complex. • Complex IDEAS and IMPRESSIONS are built up from simples.

5. THE GREAT RESEMBLANCE BETWEEN OUR IMPRESSIONS AND IDEAS • Seemingly, “all the perceptions of the mind are double, and appear both as impressions and ideas” (T, 3). • Hume commented that this is not quite correct. • “You may have the idea of a unicorn, but you have never experienced a unicorn impression.” • Reaction: “I have seen a picture of a unicorn.” • Reply: “Your experience on that occasion did not constitute an impression of a unicorn, but of a unicorn picture.” • Your idea of a unicorn is not the idea of a picture. • Consequently, you do have an idea that does not correspond to any impression; so not all our perceptions are “double”. • This observation does not hold for COMPLEX IDEAS; it does hold however for all SIMPLE IDEAS. • SIMPLE IDEA corresponds a SIMPLE IMPRESSION that resembles it.

6. RELATION OF DEPENDENCE • Every simple idea has some simple impression as a causal antecedent. • Every simple idea is a copy of a preceding impression. • What is the origin of all our ideas? • Answer: “The impressions of experience. No impression, no idea.”

7. THE ASSOCIATION OF IDEAS • What are the principles that bind these elements together to produce the rich mental life characteristic of humans? • These are principles of association. • Read E, 14. (Melchert 352b) • The three principles of connexion among ideas: (Read E, 14; cf. Melchert 353a). • Resemblance • Contiguity in time or place • Cause or effect.

8. CAUSATION: THE VERY IDEA • Fundamental Principles of the Science of Human Nature • An analysis into the elements of the mind (impressions & ideas) • The relation between them (dependence) • The principle that explain how ideas interact (association) • What are the objects of reason or enquiry? (M, p. 353; E, Sec IV, part 1, para 1) • Relations of ideas • Matters of Fact

9. RELATIONS OF IDEAS • Involve the sciences of Geometry, Algebra, etc • Every affirmation, which is either intuitively or demonstratively certain. • Ex. “The square of the hypotenuse is equal to the square of the two sides.” • Proposition of this kind is discoverable by the mere operation of thought, without dependence on what is anywhere existent in the universe. • There never were a circle or triangle in the universe. • Its falsity implies a contradiction.

10. MATTERS OF FACT • The contrary of every matter of fact is still possible. • Reason: It can never imply a contradiction, and is conceived by the mind with the same facility and distinctness, as if ever so conformable to reality. • Ex. “The sun will not rise tomorrow.” • It is no less intelligible a proposition, and implies no more contradiction, than the affirmation, that it will rise tomorrow. • Its falsehood is to be demonstrated. • It could never distinctly conceived by the mind.

11. A FURTHER EXPLANATION • Suppose we contrast these two statements: A. Two plus three is not five. B. The sun will not rise tomorrow. • Both statements are false, but in different ways.

12. “TWO PLUS THREE IS NOT FIVE.” • This statement is false simply because of the way in which the ideas “two”, “plus”, “three”, “five” and “equals” are related to each other. • Believing A as ease is to utter a contradiction. • It can be known as false “by mere operation of thought”. • Experience is not needed to know that its false.

13. “THE SUN WILL NOT RISE TOMORROW.” • Accepting this to be true does not demonstrate any contradiction. • We can clearly conceive what that would be like. • What if “we wake up to total and continuing darkness.” • The truth value of B depends on the FACTS, on what actually happens in nature. • To know its truth value, we need to consult our EXPERIENCE. • REASON alone will not suffice to convince us of matters of fact; hEre only EXPERIENCE will do.

14. FURTHER DIFFERENCE • We can be certain about A; but with respect to propositions stating matters of fact, our EVIDENCE is never great enough to amount to certainty.

15. CAN WE KNOW ONLY PHENOMENA, I.E., THE PERCEPTIONS OF THE MIND, ITS IMPRESSIONS AND IDEAS? • Nope. • We talk confidently of things beyond the reach of our senses and memory. • Ex. God and the soul, what’s going on in the next room or on the moon, of what happened long before we were born, etc. • Why? “Where someone claims to know something not present in his perceptions, you will find that a connection is being made by the relation of CAUSE & EFFECT. • It is CAUSATION that allows us to reach out beyond the limits of present sensation and memories (M, 354b).

16. FURTHER EXAMPLES • A man believes that his friend is in France. Why? He has received a letter from his friend. • You find a watch on a desert island and conclude that some human being had been there before you. • You here a voice in the dark and conclude there is another person in the room.

17. EXPLANATION OF THE EXAMPLES • In each case, a present impression is associated with an idea. • And in each case, the idea is an idea of something not present. • The way we get beliefs about matters of fact beyond the present testimony of our senses and memory by relying on our sense of causal relations.

18. HOW DO WE ARRIVE AT THE KNOWLEDGE OF CAUSE & EFFECT? • We do not, and cannot, arrive at such knowledge independently of experience,or a priori. • Our knowledge of causality is not a matter of the relation of ideas. • “No object ever discovers, by the qualities which appear to the senses, either the causes which produced it, or the effects which will arise from it; not can our reason, unassisted by experience, ever draw any inference concerning real existence and matter of fact…. Causes and effects are discoverable, not by reason, but by experience. (E, 17)

19. EXAMPLE • Think about two balls on a billiard table, the cue ball striking the eight ball, causing the eight ball to move. • Suppose we know all about the cue ball but have never had any experience whatsoever of one thing striking another. • Could we predict what would happen when the two balls meet? (Not at all.) • Why? The cue ball might simply stop, etc. • But why would we expect a movement on the second ball? • Our belief that the effect will be a movement of the second ball is completely dependent on our having observed that sort of thing on prior similar occasions. Without that experience, we would be at a total loss. • Is the prediction reasonable? If it is, provide the argument.

20. THE ARGUMENT • I have seen one ball strike another many times. • Each time, the ball which was struck has moved. Therefore: • The struck ball will move this time. • Comment: Does (3) follows from (1) and (2)? • (Not necessarily). • (This time the ball could fail to move. So argument is invalid and does not give us a good reason to believe that the second ball will move.) • But why believe that the first ball will cause the second ball to move? • Hume is searching for what, if anything, makes this a rational thing to believe. He patched up the argument.

21. PATCHING THE ARGUMENT UP • Experimentally, he added a premise to the argument. • (1a) The future will (in the relevant respect) be like the past. • Apparently, 1a + 1 + 2 = 3. • Meaning, if we know that 1a is true, then, in the light of our experience summed up in (1) and (2), it is rational to believe that the second billiard ball will move when struck by the first one. • (1a) is called the principle of the uniformity of nature.

22. COMMENT ON THE UNIFORMITY OF NATURE PRINCIPLE • How do you know that (1a) is true? • How do you know that the future will be like the past? • It is surely not contradictory to suppose that the way events hang together might suddenly change; putting the kettle on the fire after today could produce ice. • So (1a) is not true because of the relation of the ideas in it. • Whether (1a) is true or false must surely be a matter of fact. • So if we know it, we must know it on the basis of experience. • What experience?

23. EXPERIENCE EXPLAINED • If we look back, we can see that the futures we were (at various points) looking forward to always resembled the pasts we were (at those points) recalling. • How come? • (4) I have experienced many pairs of events which have been constantly conjoined in the past. • (5) Each time I found that similar pair of events were constantly conjoined in the future. Therefore: • (1a) The future will (in these respects) be like the past. • Does this hold water now? • The fact that past futures resembled past pasts is simply no good reason to think that future futures will resemble their relevant pasts. • Yet we all think that this is so. (Our practical behavior surely testifies to that belief.) • Why? Because “we believe in the uniformity of nature.” • But why? For what reason?

24. HUME’S RESPONSE TO THE QUESTION • “These two propositions are far from being the same. I have found that such an object has always been attended with such an effect, and I foresee, that other objects, which are, in appearance, similar, will be attended with similar effects. I shall allow, if you please, that the one proposition may justly be inferred from the other: I know, in fact, that it always is inferred. But if you insist that the inference is made by a chain of reasoning, I desire you to produce that reasoning. The connexion between these propositions is not intuitive. There is required a medium, which may enable the mind to draw such an inference, if indeed it be drawn by reasoning and argument. What that medium is, I must confess, passes my comprehension; and it is incumbent on those to produce it, who assert that it really exists, and is the origin of all our conclusions concerning matter of fact.”

25. REVIEW • Hume is inquiring into the foundation of ideas about things that go far beyond the contents of our present consciousness. • These ideas all depend on relations of cause and effect; they are effects caused in us by impressions of some kind. • But what is the foundation of these causal inferences? • EXPERIENCE. • But experience cannot supply a good reason, for example, for believingthat my friend is in France. • There is a gap between the premise and the conclusion. • It seems always possible that the premise might be true while the conclusion is false. • The gap is certainly there; and it seems there is no possible reason that can fill that gap. • Reason does not seem to be the right “medium” to fill the gap.

26. FOR EMPHASIS • What justifies us in believing in so many things independent of our present experience? • Not any reason! • Implication: Should we give up our belief on knowing about things that go far beyond the contents of our present consciousness? • Hume thinks we could not, even we wanted to. • Why? Hume said, “Nature will always maintain her rights, and prevail in the end over any abstract reasoning whatsoever.” (E, 27) • Furthermore, he insists that “these are beliefs living creatures such as ourselves really cannot do without. Our survival depends on them.”

27. IF NOT ANY REASON, WHAT THEN IS THE FOUNDATION OF THIS CAUSAL INFERENCE? • A thought experiment: • “Suppose a person, though endowed with the strongest faculties of reason and reflection, to be brought on a sudden into this world; he would, indeed, immediately observe a continual succession of objects, and one event following another; but he would not be able to discover anything farther. He would not, at first, by any reasoning, be able to reach the idea of cause and effect; since the particular powers, by which all natural operations are performed, never appear to the senses; nor is it reasonable to conclude, merely because one event, in one instance, precedes another, that therefore the one is the cause, the other the effect. Their conjunction may be arbitrary and casual. There may be no reason to infer the existence of one from the appearance of the other. And in a word, such a person, without more experience, could never employ his conjecture or reasoning concerning any matter of fact, or be assured of anything beyond what was immediately present to his memory and senses. Suppose, again, that he has acquired more experience, and has lived so long in the world as to have observed familiar objects or events to be constantly conjoined together; what is the consequence of this experience? He immediately infers the existence of one object from the appearance of the other.” (E, 27-28)

28. WHAT IS THE DIFFERENCE BETWEEN THE FIRST AND THE SECOND SUPPOSITION?

29. The only difference is that in the first case the man lacks sufficient experience to notice which events are “constantly conjoined” with each other.

30. BUT WHAT DIFFERENCE DOES THIS DIFFERENCE MAKE? • What allows him in the second case to make inferences and have expectations, when he cannot do that in the first case? • If it is not a matter of reasoning, then there must be • “some other principle which determines him to form such a conclusion. This principle is Custom or Habit. For wherever the repetition of any particular act or operation produces a propensity to renew the same act or operation, without being impelled by any reasoning or process of the understanding, we always say, that this propensity is the effect of Custom.” (E, 28) • “This hypothesis seems even the only one which explains the difficulty, why we draw, from a thousand instances, an inference which we are not able to draw from one instance, that is, in no respect, different from them. Reason is incapable of any such variation. The conclusions which it draws from considering one circle are the same which it would form upon surveying all the circles in the universe. But no man, having seen only one body move after being impelled by another, could infer that every other body will move after a like impulse. All inferences from experience, therefore, are effects of custom, not of reasoning.” (E, 28)

31. EXPLANATION • Our belief that events are related by cause and effect is a completely nonrational belief. • Yet, we cannot help but believe on all those things which are going beyond the range of our present impressions and memories. • It is simply by virtue of a kind of natural instinct. • That is just how human nature works: • When we experience the constant conjunction of events, we form a habit of expecting the second when we observe the first. • It is just CUSTOMARY.

32. ON CUSTOM • Hume said: • “Custom, then, is the great guide of human life. It is that principle alone which renders our experience useful to us, and makes us expect, for the future, a similar train of events with those which have appeared in the past. Without the influence of custom, we should be entirely ignorant of every matter of fact beyond what is immediately present to the memory and senses.” (E, 29) • NB: • Almost none of our most important beliefs (all of which depend on the relation between cause and effect) can be shown to be rational. • Experiencing the constant conjunction of pairs of events leads to expect the one when we experience the other. • Hume does not try to explain why human nature functions this way – it just does.

33. ON PROBABILISTIC EXPECTATIONS • But why do we sometimes expect with great certainty that an event will happen in conjunction with another event? • Sometimes a certain event is always conjoined with another event. But in other cases two events are more loosely connected in our experience. (Ex. Water always boil when put on a hot fire, but it only sometimes rains when it is cloudy.) • Meaning, our degree of belief corresponds to the degree of connection that our experience reveals between the two events. • The more constant the conjunction between event A and event B, the more probable we think it that a new experience of A will be followed by B. • Again, this is not a result of rational calculation. • We find ourselves believing those things most confidently which are most regular in our experience.

34. ON NECESSARY CONNECTION • In the two events, do you observe the necessary connection between them? • Hume is convinced that you do not. • “When we look about us towards external objects, and consider the operation of causes, we are never able, in a single instance, to discover any power or necessary connexion; any quality, which binds the effect to the cause, and renders the one an infallible consequence of the other. We only find, that the one does actually, in fact, follow the other. The impulse of one billiard-ball is attended with motion in the second. This is the whole that appears to the outward senses. The mind feels no sentiment or inward impression from this succession of objects: consequently, there is not, in any single, particular instance of cause and effect, any thing which can suggest the idea of power or necessary connexion.” (E, 41)

35. WHERE THEN DO WE GET THIS IDEA OF CAUSE? • “… upon the whole, there appears not, throughout all nature, any one instance of connexion which is conceivable by us. All events seem entirely loose and separate. One event follows another; but we never can observe any tie between them. They seem conjoined, but never connected. And as we can have no idea of any thing which never appeared to our outward sense or inward sentiment, the necessary conclusion seems to be that we have no idea of connexion or power at all, and that these words are absolutely, without any meaning, when employed either in philosophical reasonings or common life.” • HABIT is the key to understanding the concept of a cause.

36. ON HABIT • “…after a repetition of similar instances, the mind is carried by habit, upon the appearance of one event, to expect its usual attendant, and to believe that it will exist. This connexion, therefore, which we feel in the mind, this customary transition of the imagination from one object to its usual attendant, is the sentiment or impression from which we form the idea of power or necessary connexion…. When we say, therefore, that one object is connected with another, we mean only that they have acquired a connexion in our thought, and give rise to this inference, by which they become proofs of each other's existence.” (E, 50 – 51).

37. ON CAUSE • Hume is able, in this way, to give a certain legitimacy to the concept of cause. • In fact, he ventures to give a definition of a cause. • “… an object, followed by another, and where all the objects similar to the first are followed by objects similar to the second. Or in other words where, if the first object had not been, the second never had existed.” • “… an object followed by another, and whose appearance always conveys the thought to that other.”