So. Okay.
So today we're going to talk about abstract ideas and move on to Hume's theory of space and time.
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.
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.
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.
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.
So our ideas don't have some sort of aethereal intellectual existence that we
grasped by pure intellect in the way that Descartes thought some of our ideas came.
So almost inevitably you're going to lean towards Nominalism.
That is, you're going to be thinking that all of our ideas must be of particular things rather than abstract essences.
So we get Locke saying all things that exist are only particulars.
And he's echoed by Berkeley and he's echoed by HUME in the section that we're talking about, 1176.
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.
How do we get general ideas? Or if you like. How do we use general terms?
So are we going to start from Locke's theory? Because Locke's theory provides the background for both Barkley and HUME.
Arguably, they misunderstand lock. Since we want to understand HUME, we need to understand his misunderstanding of Locke.
Okay. So here is Loch on General Ideas. Ideas become general by separating from them the circumstances of time and place.
And any other ideas that may determine them to this or that particular existence.
By this way of abstraction, they are made capable of representing more individuals than one,
each of which, having in its a conformity to that abstract idea is, as we call it, of that sort.
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.
Now he gives an example. To clarify this.
Imagine a baby. First of all, gets acquainted with its mother, its father, its nurse.
And as it observes more and more people in the world, it sees they're of a similar shape.
They behave rather similarly and so on. It sees the resemblance is and forms a general idea of a person.
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,
Mary and Jane, that which is peculiar to each and retain only what is common to them all.
So the general thought is that you start with specific ideas of people.
And then you see the resemblance and you form an idea that retains what's common to them but leaves out everything that specific.
So you form a general abstract idea. Now.
Rather notoriously, Locke gave an example which Barkley made fun of.
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,
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?
It must be neither oblique nor rectangle, nor equilateral, equally cruel, in other words, isosceles nor skeleton.
But all of these. And none of these at once. In effect, it is something imperfect that cannot exist.
Now, if you try to form a general triangle image in your mind that will match up to all the
possible triangles you might encounter and not match up with anything that isn't a triangle,
even if it looks pretty triangular. You've got problems.
It's hard to see how you could form any such indeterminate image.
So Berkeley accordingly comes in and says, Well, can you form such an idea?
But you can't. And you can see that he's quoting directly from Locke's essay saying There is no such possible idea.
Locke's whole theory of abstraction is a non-starter because there's no way that we can leave
out what is specific to every individual triangle without completely destroying the idea.
So how does Berkeley think we manage to think in general terms?
Because clearly any empiricist has to give an account of this.
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.
So here is Barclay's rival account. A word becomes general by being made the sign not of an abstract general idea,
but of several particular ideas, any one of which it indifferently suggests to the mind.
And he gives an example of Law of Motion and he says,
we can think about the motion of an object when whenever we think about the motion, we have to think about a specific object.
But nevertheless, we are able to use that as an example to think more generally.
Now, the clearest example of this is probably in geometrical proof.
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.
So we have the triangle there. That's a right angle triangle.
Isosceles. But that doesn't matter. It's just a triangle.
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.
And this angle is equal to that angle because there alternate angles between parallel lines.
So the angles of the triangle add up to the three angles on a straight line.
Okay. A very familiar, uh, demonstration of a well-known geometrical truth.
And what Berkeley wants to say about this is that although when we perform the proof,
we're using a specific triangle as it happens, a right angled isosceles triangle.
Nevertheless, the proof is equally applicable to any triangle at all.
Though the idea I have in view whilst I make the demonstration be, for instance,
that of an isosceles, rectangular triangle whose sides are of a determinate length.
I may nevertheless be certain it extends to all other rectilinear triangles of what sort or bigness so ever.
And that because neither the right angle nor the equality nor determinate length of the sides are at all concerned in the demonstration.
So a very familiar practice of using a particular example as a way of reasoning more generally.
Once we've proved that the angles of that triangle add up to 180 degrees or two right angles.
We're very happy to extend that conclusion to all other triangles,
because we see that no part of our reasoning has depended on the specific characteristics of the triangles we've picked.
Okay. So that's Barclays account of abstraction. We use individual specific ideas with all their particularity, but we use them as representatives.
Now just in passing, Barclays probably a bit unfair to lock.
It's not clear that locks theory of abstraction depends on producing indeterminate
image images that will equally match all triangles and none of them.
Michael has argued this at length, but I'd just give one quotation here, which suggests, at any rate, that lock isn't quite.
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.
They do take him to have this rather naive idea with abstract images.
HUME accordingly credits Barkley with one of the most valuable discoveries that has been made recently in the Republic of Letters.
Barkley's criticism of Locke, his development of an alternative theory of general ideas is a great success.
And you get the impression from this that Hume's theory is going to be essentially the same as Barclay's.
But actually it's not quite the same because HUME gives a major role to custom.
Now. We'll see later when we come to deal with human induction.
That custom plays a major role there. Custom is habit.
We see things happen. We expect the same in the future.
And here HUME is appealing to a custom which he will later say is very similar in explaining our operation of general thought.
So when we found a resemblance among several objects, we apply the same name to all of them.
And this name plays a crucial role. After we've acquired a customer of this kind,
the hearing of that name revives the idea of one of these objects and makes the
imagination conceive it with all its particular circumstances and proportions.
So notice when we conceive if I say triangle or dog.
The idea of a particular triangle or a particular dog comes into your mind.
With all its particular features. But as the same word is supposed to have been frequently applied to other individuals,
the word not being able to revive the idea of all these individuals only revives that custom, which we have acquired by surveying them.
They're not really present to the mind, but only in power.
We keep ourselves in a readiness to survey any of them.
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,
or your idea of them are, as it were, waiting in the wings, waiting to jump in as needed in your thinking.
So all of your thinking involves very specific ideas, but other ideas are potentially there.
So. In particular, HUME says.
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.
So suppose I think of the idea of a triangle and it happens.
That's an equilateral triangle, as it were, appears in my mind.
So when I think of a triangle, I'm thinking of a specific equilateral triangle.
And then maybe the proposition occurs to me or somebody says to me, all triangles are equilateral.
Now you might think that I will be seduced into believing that because I have
this idea in my mind which I'm using as a representative of all triangles,
and it happens to be equilateral. But actually, HUME says.
We've got this magical faculty in the soul that when this happens, when some general rule is proposed to us,
which doesn't match with all of our ideas that are associated with the word triangle.
Lo and behold, by magic, as it were, another idea occurs to me and jumps in.
The custom brings to my mind an idea of a triangle that is not equilateral.
And so I see that the proposed general rule that all triangles are equilateral is false.
Okay. So to sum up, some ideas are particular in their nature.
But general in their representation.
Everything that exists is particular, but some ideas manage to become general in their representation by being annexed to a general term,
which, from a customary conjunction, has a relation to many other particular ideas and readily recalls them in the imagination.
Don Garrett has coined a useful term for the set of ideas that are associated with the term and readily recalled in this way.
He calls them the revival set very appropriate name.
Okay. So HUME has his alternative theory.
But before presenting this, he attacks Locke's theory using some similar considerations to Berkeley.
But actually he puts forward three arguments, one of them involving the severability principle,
one involving the copy principle that we've already come across,
and one involving the conceive ability principle that we've already mentioned but not discussed in much detail.
So I've put references there. I would suggest, you know, go and look at those passages, see how he argues it.
What I'm going to focus on now is the first of these, the separate ability principle,
because we'll see that that plays quite a significant role later on in Hume's philosophy.
Now. It's a little bit strange when he introduces the severability principle.
He says. We have observed that whatever objects are different are distinguishable,
and the whatever object to distinguish distinguishable are separable by the thought and imagination.
We have observed that. When did we observe that? Well, it's not quite clear.
He's never said that before.
The nearest seems to be treatise 1134, where he talks about the liberty of the imagination to transpose and change its ideas.
And he refers to that as his second principle, the first principle being the copy principle.
So it seems most plausible that when HUME suddenly starts talking about what is universally known as his severability principle,
though he doesn't call it that. But he's actually referring back to that principle of the liberty of the imagination.
Okay. And what exactly does that amount to? Whatever objects are different or distinguishable,
and then whatever objects are distinguishable are separable than the thought by the thought and imagination.
When we think of different things, we're able to separate the ideas of the.
And he goes on to say, these propositions are equally true in the inverse,
and whatever objects are separable are also distinguishable, and that whatever objects are distinguishable are also different.
So he seems to be saying that distinguish ability difference severability all come to the same thing.
Well, his argument for this is very cursory. And this is a little bit strange because we'll see.
He does actually make significant use of this principle.
He simply says, How is it possible we can separate what is not distinguishable or distinguish what is not different?
That's pretty much it. He seems to think that it's a pretty obvious principle.
Now, I suspect that what's going on here is that HUME is motivated by his general picture
of the human mind and his empiricist picture of our ideas as copied from impressions,
copied from sensation. And as always, HUME tends to model all this on a visual picture.
So although we have five senses and we get ideas from the impressions of all of those five senses.
HUME seems most of the time to be thinking in terms of visual impressions and ideas.
Okay. So when I look around me, I get a visual image.
My ideas are copied from that. And HUME seems to be working with a picture of something like a pixelated computer screen.
So I've got that image. We can divide it into lots of parts.
And my imagination gives me the freedom to take a part here.
Imagine it over there so I can move things around how I like.
And it seems to be that if you can separate out a part of that, fine.
You can distinguish it. It's different. You can move it around.
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.
It's as simple as that. But we'll see that.
HUME immediately goes on to draw quite significant conclusions from this principle, which makes it look as though maybe it's not so trivial.
In particular, it is evident at first sight that the precise length of a line is not different,
nor distinguishable from the line itself, nor the precise degree of any quality from the quality.
So straightaway you think of a line. Think of the length of a line.
You cannot distinguish those ideas. They're not separable.
So you can't think of one of them alone.
Now, that looks like a much more significant conclusion than humans, rather short justification of the principle would seem to justify.
And raises an obvious problem. Because we do seem to be able to draw these distinctions.
I can talk about the length of the line distinct from the line itself.
Maybe I can't form an idea of the line. Distinct from the idea of its length or vice versa.
But I think we have to talk about it. Okay. And think about it.
So, for example, we can distinguish between the figure and the body figured.
We can distinguish between motion and the body moved.
Recall Berkeley saying that when we think of a body in motion, we always think of the body with its specific motion.
And we may use that as a representative when thinking about moving bodies in general.
But in our thought, we cannot distinguish an abstract idea of the object that's moving from the specific motion.
So again, we've got both human Barclay and.
Saying that when we think of things, we always think of particular things in all their particularity.
So we've got this remaining problem how we can have general thoughts.
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.
And he his account of the distinction of reason,
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.
It's because of these patterns of resemblance. So suppose we see a globe of white marble.
All we get is the impression of a white colour disposed in a certain form.
So I look at a globe of white marble.
What comes to me is a white impression, or loads and loads of little white impressions, in fact, disposed in a certain way.
So I can think of the globe of white marble, I can think of its whiteness, I can think of its circularity.
I'm actually thinking of the same thing. I cannot distinguish or separate those thoughts.
However, what I can observe is different resemblances. So when I look at a globe of black marble, I see the similarity in shape.
If I look at a cube of white marble, I see the similarity in colour.
And it's because of these different patterns of resemblance that I'm able to draw the distinction between the relevant general ideas.