1
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Eight. Okay.

2
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Let's now move forward to Hume's theory of belief.

3
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Now to understand what's going on here, let's recall the agenda.

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Back in one, three, five. At the beginning of that, he said, we have three things to explain.

5
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The original impression, the transition to the idea of the connected cause or effect and the nature and qualities of that idea.

6
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So he just talked about the inference from the impression to the idea.

7
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That's the second component. He's now moving on to the third one.

8
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So one, three, seven of the nature of the idea or belief focuses on the idea.

9
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That is the idea of the effect be which arises when we make an inference from the impression of the cause.

10
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A. Well, he said that all inference about the unobserved arises from causal inference and causal inference,

11
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as we've seen moves from the impression of the cause to the idea of the effect.

12
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So we may establish as one part of the definition of an opinion or belief that tis an idea related to or associated with a present impression.

13
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He's now going to build on that and see what else is required to make something a belief.

14
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He calls this a new question on the thought of by philosophers.

15
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That's from the abstract. And it is actually quite a profound question and not an obvious one.

16
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Where in consists the difference betwixt incredulity and belief.

17
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And those of you who know about Phrygian logic may be interested to note that it's a

18
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similar question that Fraga confronted and that he used the judgement stroke to solve.

19
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Suppose we have a proposition like P implies Q notice when you say P implies Q, you're not asserting P,

20
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you're not asserting Q, you're contemplating the Proposition P and the Proposition Q and the relation between them.

21
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So you can contemplate a proposition without asserting it, without believing it.

22
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And what HUME is doing here is noticing that we can have a thought without actually believing it.

23
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So what is it? Makes the difference between a thought that we just ponder and a thought that we actually believe.

24
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It's quite a deep question. Well, first of all, it isn't the addition of some new idea.

25
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It's not that I have an idea of a particular thing, and then I add to it the idea of existence.

26
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And that makes it a belief, because we know that there isn't any separable idea of existence.

27
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We dealt with that back in one, two, six four. Another point is, I believe Proposition P and you don't you disagree with me.

28
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The same ideas must be involved or it wouldn't be the same proposition.

29
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If I believe in you disbelieve p. If our ideas are different, then we're actually at cross-purposes.

30
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So the difference between believing and just pondering an idea a a proposition

31
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must lie in the manner of conception rather than the content of the proposition.

32
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So it's not to do with the nature of the ideas themselves. It's the manner of their conception.

33
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And HUME talks about this as force and vivacity. The reason he goes for force and vivacity seems to be that it's the it's the only thing he thinks,

34
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the only kind of characteristic of an idea which could change the manner of the idea

35
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of the manner in which it appears to you without actually changing the idea itself.

36
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But it is quite problematic as we'll see. Okay.

37
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So we can now fill out the definition of belief.

38
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An opinion, therefore, or belief may be most accurately defined a lively idea related to or associated with a present impression.

39
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So all belief in things that are unobserved, according to HUME, comes from causal inference.

40
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That means it has to start from what he loosely called an impression of the memory or senses.

41
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And that leads us to an idea, an associated idea, which is a lively idea, and that is what a belief is.

42
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No, I've said that appealing to force and vivacity is not entirely satisfactory.

43
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Suppose you're reading a novel that might strike you with much more fulsome vivacity

44
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than the ideas that you get from reading a dull history that you believe the history.

45
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You don't believe the novel. So how does that fit? If fulsome vivacity is what makes the difference to a belief that doesn't seem to work,

46
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and how does fulsome vivacity think fit into the theory of ideas?

47
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I mean, HUME has said that all the perceptions of mind, the mind resolves themselves into impressions and ideas.

48
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Well, is fulsome vivacity some kind of extra feeling?

49
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In which case, presumably, it's an impression. So what?

50
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Why doesn't that make a difference to what you're thinking about?

51
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If the force and vivacity is part of the idea. If when you have a belief, what happens is that the idea itself becomes more forceful and vivacious,

52
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then how can we distinguish between believing that there's a dull red door and imagining a bright red door?

53
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On the face of it, the extra brightness there in our thought of the door provides more fulsome vivacity.

54
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So how does that not make it into a belief? Now humans talk about manner of conception seems to be rather happier.

55
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That seems to be more on the right track.

56
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Fulsome vivacity ought not to be something that goes within the ideas, as it were, because otherwise we run into these problems very seriously.

57
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It seems more satisfactory to think of belief as some kind of manner of conception,

58
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the way in which we grasp or our attitude to those ideas, rather than the nature of the ideas themselves.

59
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But notice that that doesn't fit terribly well with Hume's theory of ideas.

60
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In particular, it can provide some conflict with Hume's theory of personal identity.

61
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We'll come to that later. HUME wants to say that we don't have any conception of a person other than lots and lots of fleeting impressions and ideas,

62
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sort of bundle of perceptions. And it's not clear how a manner of conception can fit with that kind of picture.

63
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So there are quite a lot of problems here, and we do see some symptoms of unease.

64
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So HUME added a paragraph to the appendix of 1740.

65
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The appendix came out at the end of 1740, along with book three of the treaties,

66
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and he included in it a few extra paragraphs and footnotes and so forth to be inserted in books one and two.

67
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And this is one of them. An idea assented to feels different from a fictitious idea of this different feeling.

68
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I endeavoured to explain by calling it a superior force or vivacity or solidity or firmness or steadiness.

69
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It is impossible to explain perfectly this feeling or manner of conception.

70
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We may make use of words that express something near it.

71
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But its true and proper name is belief, which is a term that everyone sufficiently understands.

72
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So ultimately he seems to be rather giving up on explaining what belief is.

73
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He seems to be just saying belief, you know? You know what that is, don't you?

74
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That's its name. And he hasn't really given us a very satisfactory account of what it is.

75
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However, back to 1739, and he does think he can give something like a satisfactory theory of belief.

76
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So notice that we've got two discoveries which have a rather neat connection.

77
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Causal reasoning starts from an impression of the senses or memory.

78
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They're distinguished from mere ideas by their force and vivacity.

79
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Indeed, that force or vivacity. HUME says their constitutes their belief or assent.

80
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And now we've concluded that something that is inferred by causal inference becomes a belief in virtue of its force and vivacity.

81
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Well, that's a very nice coincidence. We get the hydraulic theory of belief.

82
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That's my term for it.

83
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I would willingly establish it as a general maxim in the science of human nature that when any impression becomes present to us,

84
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it not only transports the mind to such ideas as are related to it, but likewise communicates to them a share of its force and vivacity.

85
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I call this the hydraulic theory because it's as though you've got force and vivacity squirting into the inference from the impression.

86
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And then it goes into the idea, fills up the idea, and the idea becomes more forceful and vivacious.

87
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In fact, HUME goes further when he discusses probability, which we'll be coming back to in a future lecture.

88
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He extends this you get the false and vivacity being divided into different channels,

89
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and that leads you to having different probable beliefs in the various possible outcomes.

90
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So he does seem to take the hydraulic model quite seriously.

91
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Okay. I'm going to end with two quite important passages from 138 well-known passages and quite significant.

92
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So he's summing up his theory of belief, and he says thus all probable reasoning is nothing but a species of sensation.

93
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It is not solely in poetry, in music. We must follow our taste and sentiment.

94
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But likewise in philosophy. When I'm convinced of any principle, it is only an idea which strikes more strongly upon me.

95
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So it's as though we are simply creatures being buffeted around by these associational processes in our mind.

96
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They lead force and vivacity to be applied to certain ideas.

97
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When the force and vivacity is applied to those ideas, I end up with a belief.

98
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And belief is a sort of feeling. It's all about sensation.

99
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Very, very anti rationalist. Notice he's more or less saying that when we reason probably probable reasoning.

100
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Causal reasoning. Essentially it's the associational processes that are driving it, not reason.

101
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Again, it's looking pretty sceptical. Also, quite importantly, the uniformity principle is typically unconscious.

102
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So when we infer one thing from another causally, typically we do it without a moment's thought.

103
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He gives the example of a man coming to a river and stopping at the river.

104
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And it's not that the man is reflecting on his past experience and thinking, Well, if I go on into the river, I could drown, and so forth.

105
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The idea of the river and the idea of getting wet and drowning comes so immediately to him that he doesn't need to reflect on past experience at all.

106
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It's pretty much automatic.