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So. Okay.

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So today we're going to talk about abstract ideas and move on to Hume's theory of space and time.

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Now the theory of abstract ideas or general ideas occurs in the last section of book one, part one, and it's got a lot packed in there.

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It's actually of quite an important section. HUME brings quite a lot of principals to bear, and he's going to appeal to those later on.

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So if we seem to be spending rather too much time on book one, part one, and this section in particular, it is with good reason.

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Now. Imagine that you're empiricist like Locke or Berkeley or HUME in the sense that you think all our ideas are derived from experience.

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So our ideas don't have some sort of aethereal intellectual existence that we

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grasped by pure intellect in the way that Descartes thought some of our ideas came.

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So almost inevitably you're going to lean towards Nominalism.

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That is, you're going to be thinking that all of our ideas must be of particular things rather than abstract essences.

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So we get Locke saying all things that exist are only particulars.

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And he's echoed by Berkeley and he's echoed by HUME in the section that we're talking about, 1176.

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Now, if the only things we encounter and experience are particulars, this raises the question of how we are able to think in general terms.

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How do we get general ideas? Or if you like. How do we use general terms?

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So are we going to start from Locke's theory? Because Locke's theory provides the background for both Barkley and HUME.

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Arguably, they misunderstand lock. Since we want to understand HUME, we need to understand his misunderstanding of Locke.

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Okay. So here is Loch on General Ideas. Ideas become general by separating from them the circumstances of time and place.

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And any other ideas that may determine them to this or that particular existence.

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By this way of abstraction, they are made capable of representing more individuals than one,

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each of which, having in its a conformity to that abstract idea is, as we call it, of that sort.

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So the way in which we rank things into sorts is by producing what Locke calls abstract ideas and checking whether things match up against them.

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Now he gives an example. To clarify this.

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Imagine a baby. First of all, gets acquainted with its mother, its father, its nurse.

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And as it observes more and more people in the world, it sees they're of a similar shape.

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They behave rather similarly and so on. It sees the resemblance is and forms a general idea of a person.

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Locks as man. And in forming that idea, they make nothing new but only leave out of the complex idea they had of Peter and James,

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Mary and Jane, that which is peculiar to each and retain only what is common to them all.

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So the general thought is that you start with specific ideas of people.

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And then you see the resemblance and you form an idea that retains what's common to them but leaves out everything that specific.

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So you form a general abstract idea. Now.

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Rather notoriously, Locke gave an example which Barkley made fun of.

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Uh. It's a little bit unfair in a way, because what he's doing in this part of the essay is explaining how difficult it is to form abstract ideas,

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why it's rather difficult for children to do it. Doesn't it require some pains and skill to form the general idea of a triangle?

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It must be neither oblique nor rectangle, nor equilateral, equally cruel, in other words, isosceles nor skeleton.

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But all of these. And none of these at once. In effect, it is something imperfect that cannot exist.

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Now, if you try to form a general triangle image in your mind that will match up to all the

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possible triangles you might encounter and not match up with anything that isn't a triangle,

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even if it looks pretty triangular. You've got problems.

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It's hard to see how you could form any such indeterminate image.

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So Berkeley accordingly comes in and says, Well, can you form such an idea?

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But you can't. And you can see that he's quoting directly from Locke's essay saying There is no such possible idea.

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Locke's whole theory of abstraction is a non-starter because there's no way that we can leave

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out what is specific to every individual triangle without completely destroying the idea.

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So how does Berkeley think we manage to think in general terms?

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Because clearly any empiricist has to give an account of this.

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He might not say that we have these weird general ideas, but he's got to give some account of how we manage to do general thinking.

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So here is Barclay's rival account. A word becomes general by being made the sign not of an abstract general idea,

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but of several particular ideas, any one of which it indifferently suggests to the mind.

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And he gives an example of Law of Motion and he says,

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we can think about the motion of an object when whenever we think about the motion, we have to think about a specific object.

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But nevertheless, we are able to use that as an example to think more generally.

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Now, the clearest example of this is probably in geometrical proof.

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And Berkeley gives such an example. So here we have a diagram that one might use to prove that the angles of a triangle add up to two right angles.

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So we have the triangle there. That's a right angle triangle.

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Isosceles. But that doesn't matter. It's just a triangle.

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We draw a line here that's parallel to the other line. And you can see that this angle is equal to that angle because they're corresponding angles.

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And this angle is equal to that angle because there alternate angles between parallel lines.

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So the angles of the triangle add up to the three angles on a straight line.

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Okay. A very familiar, uh, demonstration of a well-known geometrical truth.

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And what Berkeley wants to say about this is that although when we perform the proof,

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we're using a specific triangle as it happens, a right angled isosceles triangle.

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Nevertheless, the proof is equally applicable to any triangle at all.

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Though the idea I have in view whilst I make the demonstration be, for instance,

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that of an isosceles, rectangular triangle whose sides are of a determinate length.

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I may nevertheless be certain it extends to all other rectilinear triangles of what sort or bigness so ever.

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And that because neither the right angle nor the equality nor determinate length of the sides are at all concerned in the demonstration.

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So a very familiar practice of using a particular example as a way of reasoning more generally.

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Once we've proved that the angles of that triangle add up to 180 degrees or two right angles.

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We're very happy to extend that conclusion to all other triangles,

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because we see that no part of our reasoning has depended on the specific characteristics of the triangles we've picked.

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Okay. So that's Barclays account of abstraction. We use individual specific ideas with all their particularity, but we use them as representatives.

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Now just in passing, Barclays probably a bit unfair to lock.

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It's not clear that locks theory of abstraction depends on producing indeterminate

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image images that will equally match all triangles and none of them.

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Michael has argued this at length, but I'd just give one quotation here, which suggests, at any rate, that lock isn't quite.

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I'm in the position that Berkeley thinks he is. But at any rate, as I've said, both Bartley and HUME treat lock as a foil.

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They do take him to have this rather naive idea with abstract images.

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HUME accordingly credits Barkley with one of the most valuable discoveries that has been made recently in the Republic of Letters.

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Barkley's criticism of Locke, his development of an alternative theory of general ideas is a great success.

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And you get the impression from this that Hume's theory is going to be essentially the same as Barclay's.

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But actually it's not quite the same because HUME gives a major role to custom.

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Now. We'll see later when we come to deal with human induction.

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That custom plays a major role there. Custom is habit.

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We see things happen. We expect the same in the future.

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And here HUME is appealing to a custom which he will later say is very similar in explaining our operation of general thought.

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So when we found a resemblance among several objects, we apply the same name to all of them.

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And this name plays a crucial role. After we've acquired a customer of this kind,

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the hearing of that name revives the idea of one of these objects and makes the

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imagination conceive it with all its particular circumstances and proportions.

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So notice when we conceive if I say triangle or dog.

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The idea of a particular triangle or a particular dog comes into your mind.

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With all its particular features. But as the same word is supposed to have been frequently applied to other individuals,

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the word not being able to revive the idea of all these individuals only revives that custom, which we have acquired by surveying them.

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They're not really present to the mind, but only in power.

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We keep ourselves in a readiness to survey any of them.

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So you think of a specific dog. But because the word dog has been associated by you with lots of other specific animals, those other specific animals,

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or your idea of them are, as it were, waiting in the wings, waiting to jump in as needed in your thinking.

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So all of your thinking involves very specific ideas, but other ideas are potentially there.

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So. In particular, HUME says.

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Suppose some proposition is put to us which may match with the particular idea we're thinking of at the moment, but doesn't match in general.

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So suppose I think of the idea of a triangle and it happens.

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That's an equilateral triangle, as it were, appears in my mind.

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So when I think of a triangle, I'm thinking of a specific equilateral triangle.

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And then maybe the proposition occurs to me or somebody says to me, all triangles are equilateral.

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Now you might think that I will be seduced into believing that because I have

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this idea in my mind which I'm using as a representative of all triangles,

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and it happens to be equilateral. But actually, HUME says.

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We've got this magical faculty in the soul that when this happens, when some general rule is proposed to us,

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which doesn't match with all of our ideas that are associated with the word triangle.

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Lo and behold, by magic, as it were, another idea occurs to me and jumps in.

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The custom brings to my mind an idea of a triangle that is not equilateral.

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And so I see that the proposed general rule that all triangles are equilateral is false.

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Okay. So to sum up, some ideas are particular in their nature.

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But general in their representation.

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Everything that exists is particular, but some ideas manage to become general in their representation by being annexed to a general term,

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which, from a customary conjunction, has a relation to many other particular ideas and readily recalls them in the imagination.

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Don Garrett has coined a useful term for the set of ideas that are associated with the term and readily recalled in this way.

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He calls them the revival set very appropriate name.

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Okay. So HUME has his alternative theory.

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But before presenting this, he attacks Locke's theory using some similar considerations to Berkeley.

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But actually he puts forward three arguments, one of them involving the severability principle,

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one involving the copy principle that we've already come across,

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and one involving the conceive ability principle that we've already mentioned but not discussed in much detail.

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So I've put references there. I would suggest, you know, go and look at those passages, see how he argues it.

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What I'm going to focus on now is the first of these, the separate ability principle,

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because we'll see that that plays quite a significant role later on in Hume's philosophy.

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Now. It's a little bit strange when he introduces the severability principle.

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He says. We have observed that whatever objects are different are distinguishable,

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and the whatever object to distinguish distinguishable are separable by the thought and imagination.

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We have observed that. When did we observe that? Well, it's not quite clear.

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He's never said that before.

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The nearest seems to be treatise 1134, where he talks about the liberty of the imagination to transpose and change its ideas.

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And he refers to that as his second principle, the first principle being the copy principle.

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So it seems most plausible that when HUME suddenly starts talking about what is universally known as his severability principle,

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though he doesn't call it that. But he's actually referring back to that principle of the liberty of the imagination.

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Okay. And what exactly does that amount to? Whatever objects are different or distinguishable,

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and then whatever objects are distinguishable are separable than the thought by the thought and imagination.

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When we think of different things, we're able to separate the ideas of the.

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And he goes on to say, these propositions are equally true in the inverse,

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and whatever objects are separable are also distinguishable, and that whatever objects are distinguishable are also different.

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So he seems to be saying that distinguish ability difference severability all come to the same thing.

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Well, his argument for this is very cursory. And this is a little bit strange because we'll see.

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He does actually make significant use of this principle.

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He simply says, How is it possible we can separate what is not distinguishable or distinguish what is not different?

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That's pretty much it. He seems to think that it's a pretty obvious principle.

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Now, I suspect that what's going on here is that HUME is motivated by his general picture

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of the human mind and his empiricist picture of our ideas as copied from impressions,

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copied from sensation. And as always, HUME tends to model all this on a visual picture.

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So although we have five senses and we get ideas from the impressions of all of those five senses.

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HUME seems most of the time to be thinking in terms of visual impressions and ideas.

151
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Okay. So when I look around me, I get a visual image.

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My ideas are copied from that. And HUME seems to be working with a picture of something like a pixelated computer screen.

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So I've got that image. We can divide it into lots of parts.

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And my imagination gives me the freedom to take a part here.

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Imagine it over there so I can move things around how I like.

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And it seems to be that if you can separate out a part of that, fine.

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You can distinguish it. It's different. You can move it around.

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And this seems to make sense of how. I've suggested he's referring back to what he called the liberty of the imagination to transpose our ideas.

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It's as simple as that. But we'll see that.

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HUME immediately goes on to draw quite significant conclusions from this principle, which makes it look as though maybe it's not so trivial.

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In particular, it is evident at first sight that the precise length of a line is not different,

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nor distinguishable from the line itself, nor the precise degree of any quality from the quality.

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So straightaway you think of a line. Think of the length of a line.

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You cannot distinguish those ideas. They're not separable.

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So you can't think of one of them alone.

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Now, that looks like a much more significant conclusion than humans, rather short justification of the principle would seem to justify.

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And raises an obvious problem. Because we do seem to be able to draw these distinctions.

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I can talk about the length of the line distinct from the line itself.

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Maybe I can't form an idea of the line. Distinct from the idea of its length or vice versa.

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But I think we have to talk about it. Okay. And think about it.

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So, for example, we can distinguish between the figure and the body figured.

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We can distinguish between motion and the body moved.

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Recall Berkeley saying that when we think of a body in motion, we always think of the body with its specific motion.

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And we may use that as a representative when thinking about moving bodies in general.

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But in our thought, we cannot distinguish an abstract idea of the object that's moving from the specific motion.

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So again, we've got both human Barclay and.

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Saying that when we think of things, we always think of particular things in all their particularity.

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So we've got this remaining problem how we can have general thoughts.

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So. HUME At the end of Section seven. Talks about what he calls the distinction of reason, which is so much talked about and so much misunderstood.

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And he his account of the distinction of reason,

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the way we can distinguish between the body and the body moved is by means of his theory of abstraction or theory of general ideas.

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It's because of these patterns of resemblance. So suppose we see a globe of white marble.

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All we get is the impression of a white colour disposed in a certain form.

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So I look at a globe of white marble.

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What comes to me is a white impression, or loads and loads of little white impressions, in fact, disposed in a certain way.

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So I can think of the globe of white marble, I can think of its whiteness, I can think of its circularity.

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I'm actually thinking of the same thing. I cannot distinguish or separate those thoughts.

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However, what I can observe is different resemblances. So when I look at a globe of black marble, I see the similarity in shape.

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If I look at a cube of white marble, I see the similarity in colour.

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And it's because of these different patterns of resemblance that I'm able to draw the distinction between the relevant general ideas.