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So what is the distinction between primary and secondary qualities?

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It is not, as Barkley and Hume thought, that primary qualities are in objects and secondary qualities aren't.

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That's not the distinction.

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It's rather that the ideas of primary qualities are resemblances of them, and their patterns do really exist in the bodies themselves.

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But the ideas produced in us by these secondary qualities have no resemblance of them at all.

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There is nothing like our ideas existing in the bodies themselves.

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So when I say that something around yellow thing is round, I'm attributing a property to it which resembles my idea,

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the roundness of the object and the roundness, as it were, as perceived by me, are supposed to resemble.

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Whereas the yellowness of the object is not a resemblance of my idea at all.

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My idea of yellow,

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the phenomenal character of the yellowness that I see is completely different from whatever it is in the object that causes that idea.

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Yellowness in the object is a matter we speculate of the micro structure, the surface texture, the corpuscles,

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the shape of the corpuscles, how they're arranged, the way that light reflects off them and so forth.

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And its resemblance, rather than presence in the object that distinguishes primary and secondary qualities.

15
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OK, now Barkley famously attacks Locke on this, as on many other things.

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And Berkeley wants to say that an idea cannot resemble an object, an idea can be like nothing but an idea,

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a colour or figure can be like nothing but another colour or figure.

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So he attacks Locke's claim concerning resemblance.

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He wants to say that ideas are, as it were, intrinsically perceivable.

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There's something about them which just in their very nature has to be perceived.

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Now, I think this is very plausible with secondary qualities. Suppose, for example.

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You imagine the smell of lavender. Imagine that I've got some lavender essence and I sprinkle it around the lecture theatre and.

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And you sniff it. You'll get that smell. That smell of lavender.

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Right. Could that smell exist outside the mind?

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I don't mean the substance that causes the smell. I mean the smell itself. That could that exist outside of mind?

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No, surely not.

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If nobody existed, if there were none of us, there were no people to have that smell or no animals to have that smell, then the smell would not exist.

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Even if the substance did, it is plausible to say that nothing physical can be like a smell.

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A smell is just intrinsically something which has to be in the mind, has to be perceived in order to exist.

30
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That's a very plausible claim. OK.

31
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Now think about a colour. Think about the yellowness of that light.

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And I don't mean whatever it is that causes the yellow. Now, I mean the perceived yellowness, the phenomenal idea that you get.

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Think of the difference between yellow and red or blue or whatever.

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It feels different to us. It looks different. Can that look exist outside the mind?

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Plausibly not. Plausibly, the look, the phenomena, look what it is like to see it can only exist by someone actually seeing it,

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just as the smell can only exist by someone actually smelling it.

37
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So if you think of things in that way, barclays' principle that for ideas there being is there being perceived seems very plausible.

38
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But what about primary qualities? We think, well, the roundness of the light.

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Wow. That's not the same.

40
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I look at the light and I see it as round and I don't feel anything like the same reluctance to say that a real object can be round.

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The roundness is not something that can only exist by being perceived,

42
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at least that it's our natural inclination to say that, and Berkeley wants to argue against that.

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And in the case of primary qualities, you can see he's got much more of an uphill battle arguing the point.

44
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It doesn't seem that ideas of primary qualities have quite the same intimate connexion with being perceived with mentality.

45
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And part of the reason is that they're more abstract and structural.

46
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We can use the abstract mathematical properties of shapes to think about them in a way that seems to correspond with the real world I'm given.

47
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I'll give an example. Imagine that you have.

48
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A rectangle. OK, now imagine a diagonal line drawn from the bottom left corner of the rectangle to the top right corner of the rectangle.

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Now, imagine a vertical line bisecting the wreck, that rectangle.

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So it so it goes from the middle of the top to the middle of the bottom. From the point where those two lines meet.

51
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Imagine a horizontal line being drawn to the right. Where does it cross the boundary of the rectangle?

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And you will all say, well, halfway up the right hand side. And you'd be right.

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I hope so. Now, we can do that sort of imagining,

54
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we can imagine an idea and we think actually correctly that if we were to do that with physical objects and so on, everything would work out.

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We would find that the kind of thinking we are doing, the structural thinking we're doing does seem to match up with physical objects in the world.

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And that goes together with the fact that attributing to objects,

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properties that are structurally similar to our mental picture of them does actually work.

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Which makes it quite plausible that the objects in themselves, though perhaps in many ways very, very different from our conception of them,

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nevertheless have a sort of structural isomorphic them a similar structure to the way we conceive of them,

60
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at least in respect of their shapes, size and so forth.

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If you want to read more on this Jonathan Lowe's book on Lock, the Routledge book discusses these sorts of issues.

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The pages I've referred to there. OK.

63
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So we can make some sense of primary qualities in general, like shape and size and motion.

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Resembling somehow our ideas of them. It seems, at any rate, to make a lot more sense than the thought of.

65
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Primary qualities resembling a smell or a colour. But solidity seems to be a bit of an odd man out here.

66
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OK, so we've got a nice divide between primary quality, secondary qualities.

67
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We've got secondary qualities that seem to be intimately connected with perception.

68
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We've got primary qualities which seem to be more abstract and structural, and we seem to be able to make some sense,

69
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at least of our ideas of primary qualities resembling primary qualities in the objects themselves.

70
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But solidity does my idea of solidity resemble solidity?

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And the object itself can make any sense of that. That's not so clear.

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How do I get my idea of solidity? Well, I get it by kind of pushing against things or seeing one thing bash into another and knock it out of the way.

73
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It looks like my only idea of solidity comes from.

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Seeing things behave in a particular way,

75
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I don't seem to have any intrinsic idea of solidity in the way that I might do of a shape or a size or a movement.

76
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So when we say that objects are solid, it's not clear that we really understand in any intimate way what we're saying.

77
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Solidity seems to be a power, a disposition, a way of behaving.

78
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It's the power to exclude other bodies. So what's a body then?

79
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Well, a body is something solid.

80
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But if we can't understand solidity except as a power to exclude other solid bodies, it looks like we're just going in a circle.

81
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So here is David Hume attacking on precisely this line.

82
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Two nonentities cannot exclude each other from their places.

83
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Now, I ask, what idea do we form of these bodies or objects to which we suppose solidity to belong?

84
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To say that we conceive them merely as solid is to run on in infant item.

85
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Extension must necessarily be considered either as coloured,

86
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which is a false idea because it's a secondary quality, which we're supposing not to be an object or a solid.

87
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Which brings us back to the first question. Hence, after the exclusion of colours and so forth from the rank of external existences,

88
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there remains nothing which can afford us a just and consistent idea of body.

89
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So what humans saying here is. The particular idea of solidity is highly problematic.

90
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It doesn't seem to fit in to the category of ideas which we can coherently form

91
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and somehow written an idea of object as resembling the way we conceive of them.

92
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And if you try to get an adequate conception of solidity, you fail.

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You have to think of a body as excluding other bodies,

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but the only sense you can form of that is either to think of a body as a coloured expense or to think of it as a solid expense.