Okay. Today, the topic is a double one dealing with perception and the primary secondary quality distinction. These are very closely related topics, as we'll see the various luminaries here, all of whom have something to do with Oxford. Robert Boyle, who did his famous experiments more or less founding the science of chemistry in Oxford. John Locke of Christchurch. Bishop Berkeley, who died and is buried in Oxford. He was visiting his son, Christchurch at the time, A.J. Eyre,
who was Wiccan professor of logic at New College, J.L. Austin, and Peter Straughan, whom we've already met. Now, as he explained in the introductory lectures.
A lot of these problems arose precisely because of the development of modern science in the early modern period, in particular the move away from Aristotelian ism to a mechanical account of the world implied explaining perception, not in terms of some kind of thing coming from the object to the eye, which was somehow intrinsically similar to the object, so that we directly grasp its qualities, but rather in terms of causal intermediaries, particles or waves,
little particles of light that bounce off the objects and come to our eyes and then interpreted by our brains in order to give us perception of objects. Now, obviously, the issue doesn't only affect organs of sight, but all of our senses. But most of the discussions of this period tend to be focussed on site or to some extent, touch. Those are the senses that seem to come closest to giving us a. A presentation of objects as they are altogether.
Now, this kind of view of the world started, as we saw with Galileo and Descartes, but Locke's account is the one that was most influential. So when people discuss these issues, it's typically against the background of a Lockean account of perception and the primary secondary quality distinction. So what are objects like when we perceive objects? When we see them in particular? There are impressions caused in us, in our brain somehow by a means of our sense organs, particularly our eyes.
But we hypothesise that these are caused by particles or waves of light coming from the objects and the properties of those particles or waves. Bear no resemblance at all to the objects themselves. They somehow convey that information. But we are aware that there is very complex processing goes that goes on with the particles or waves hitting the retina. Messages travelling down the optic nerve, somehow being synthesised by the brain and so on.
First of all, it does imply that that intermediary process involves things that are quite unlike either the perceptions that we have mentally and also probably quite unlike the objects themselves. If we're thinking in terms of a mechanical paradigm that the best explanation of how things happen is basically things bashing into each other, then that naturally suggests that the explanation of all this process had better be in mechanical terms.
We'll naturally see geometrical and dynamical properties, things like shape and size and motion as being the crucial causal determinants of what happens. Now, John Locke, as we've seen before, took over Boyle's corpuscular arean hypothesis. He mentions it actually explicitly in the essay only once, the book for part three, search a Section 16. He doesn't commit himself to this. He doesn't say this is definitely the right account of things.
But he says this seems to come closest to an intelligible explanation of how things work. So the corpuscular arean hypotheses, a hypothesis explains the properties of different substances, say gold or lead or whatever it may be, as arising from their particular micro structure.
So the hypothesis is that the micro structure of gold is different from the micro structure of lead in a way that explains their different properties, why they have the colour they do, why they melt at the temperature that they melt. Why they're as hard as they are and so on. So the micro structure is supposed to consist of lots of little corpuscles. Now these corpuscles are likely to vary between the different substances.
Presumably they do vary. They might vary in shape, in size and in organisation. They might be differently packed, say. But the corpuscular arean hypothesis involves the conjecture that all of these corpuscles are made of the same stuff. So they may vary in their properties, shape and size and so on, but they're made of the same stuff, which Boyle called universal matter. And when Locke talks about pure substance in general, it seems likely that he is referring to the same kind of thing.
Except, of course, when Locke talks about pure substance in general and the ideas we have of it, he doesn't want to commit himself to the corpuscular Aryan hypothesis. So he's talking about the stuff of which things are made. Whatever that is, on the corpuscular in hypothesis, it would be the universal matter from which the corpuscles are composed.
So this underlying substance is hypothesised to have primary qualities, that is shape, size, movement, texture and what Boyle called impenetrability and what Locke called solidity. And these are the qualities which are supposed to belong, as it were, intrinsically to the stuff. And those are the qualities in terms of which the appearance of the stuff to us is to be explained.
So the secondary qualities, things like colour, smell, taste, the qualities that appear to us are explained by the primary qualities they are in themselves. Nothing like what we see. So when I see something. Suppose I look at the light and I see it as yellow. There is nothing in the light remotely like my idea of yellowness. It's rather that the primary qualities somehow cause that idea in me. So being yellow is a matter of having the power to produce the idea of yellow.
That phenomenal idea that we are familiar with from seeing yellow, it's having the power to produce that in an observer who's suitably placed. So let's focus on the problem here by considering the case of a circular hot plate. Suppose there's an electric hot plate on an oven and it's been heated up until it's glowing red hot. Okay, quite familiar. I bring my hand close to the hot plate and I feel warmth.
I bring it still closer and I feel pain. Well, the sensations are felt, warmth and pain are clearly in the mind. We do not attribute the pain to the hotplate itself. We're not even tempted to do that. Warmth. Maybe less clear, but at least the felt sensation of warmth. We won't attribute that to it. The circular shape. Well, we are inclined to attribute that to the object, the hotplate really is circular.
We think. What about the red colour? The red circle that we see when we look at the hot plate, is that in the mind or is it in the object? And you can see that there's a bit of a tension here. When we look at objects and see them as coloured, we're naturally inclined to think of the colour as they're in the object. But if we start speculating about the mechanisms of perception, as one naturally does it in the early modern period. And now, of course.
You're naturally led to think, hang on, it can't be like that, though, we're inclined to attribute the redness to the thing itself. Actually, there's no way there can be anything remotely like the redness in the object. Now, there's a well-known text in Locke's essay, a book to Chapter eight, Section 10. Which is quite notorious. Lock here is drawing a distinction between primary and secondary qualities. And he is discussing what he understands by a secondary quality.
So he talks about such qualities, which in truth are nothing in the objects themselves, but powers to produce various sensations in us by their primary qualities, i.e. by the bulk figure, texture and motion of their insensible parts as colours, sounds, tastes, etc. These I call secondary qualities. Okay. So you've got the primary qualities in the object, the bulk figure, texture, motion.
You've got the secondary qualities, colours, sounds, tastes and so forth, which are, he says, nothing in the objects themselves but powers to produce ideas in us. Now, that comma before, but is rather unfortunate. It gives the impression that Locke is saying that secondary qualities are nothing in the objects themselves. That's quite different from saying that they're nothing in the object but powers, then nothing but powers.
They are in the object, but they are powers. Now, some people have interpreted like one way, some the other. I think it's quite clear that Locke does think that secondary qualities are in object, but secondary qualities in objects are powers. Now, Berkeley read Locke as denying that secondary qualities are in objects. He thought Locke was saying that secondary qualities are just in the mind, not in objects.
But Locke is actually pretty clear on the matter. If you look at his chapter on the adequacy of ideas, so I've quoted a little passage there. Now, an adequate idea is one which faithfully represents what it is the idea of. So whether an idea is adequate or not depends on the faithfulness of the representation and lock being a An empiricist is trying to find a suitable foundation for our knowledge.
How can we know that any of our perceptions of the world are securely anchored in the way things are? And lot comes up with a very ingenious solution to this. It's really quite clever. Take the simple idea of yellow that I get from looking at something yellow, just that particular colour, not the shape, just the yellowness. And I ask myself, is that thing really yellow? Is my idea of yellow a faithful representation of what is there?
And Locke says, yes, it is definitely simple ideas are certainly adequate because being intended to express nothing but the power in things to produce in the mind such a sensation, it follows. Since I see the yellow, the thing itself must have the power to produce that idea. And that's all I mean by calling it yellow, that it has that power. Therefore, my idea must be adequate. Very ingenious. If something causes the idea of yellow in me, then that is its being yellow.
There's nothing more to being yellow than having the power to produce the idea in me. So at least we can tick off the simple ideas like yellow as corresponding to the way things are. Now that's quite important. It's an important epistemological point and a very subtle and clever one. Locke is saying that an object being yellow is not a matter of there being anything in the object that resembles my idea of yellow.
It's simply a matter of the object having whatever qualities it is that normally a naturally produce the idea of yellow. So that gives us something solid epistemologically to build on. And this is just one example of a quite fundamental shift between Descartes and Locke.
Descartes looks at a piece of wax in meditation, too, and finds that his sensory perceptions are leading him radically astray and reckons that the only way that he can get a proper, adequate idea of what's there is to use his intellect to penetrate into the nature of matter and see that its essence is extension. So Descartes wants to found everything on intellectual perception. But here is Locke founding everything on sensory perception and saying here we have a solid anchor.
So it's quite a deep move. But at this point, I'm just mainly using it to to prove that Locke does think that secondary qualities are in objects. So when you read Locke and Berkeley on these things, it's worth bearing in mind that Berkeley and indeed Hume get Locke wrong in this particular.