6.1 Introduction to Primary and Secondary Qualities

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 and the various luminaries here all of whom have something to do with Oxford was 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 in his buried in Oxford he was visiting his son at Christchurch at the time AJ Ayer who was Wickham professor of logic at New College JL Austin and Peter Strawson 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 grasped 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 are then interpreted by our brains in order to give us a perception of objects now obviously the 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 focused on sight or to some extent touch those are the senses that seem to come closest to giving us a presentation of objects as they are all together 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 object when we see them in particular there are impressions caused in us in our brains somehow by a means of our sense organs particularly our eyes but we hypothesize 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're aware that there is very complex processing goes that goes on with the particles or waves hitting the retina no messages traveling down the optic nerve somehow being synthesized 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 thing as bashing into each other then that naturally suggests that the explanation of all this process had better be in mechanical terms will 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 Boyles corpuscular ian hypothesis he mentions it actually explicitly in in the essay only once the book for the part three section sixteen 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 Ian's hypotheses a hypothesis explains the properties of different substances say gold or LED or whatever it may be as a rising from their particular microstructure so the hypothesis is that the microstructure of gold is different from the microstructure of lead in a way that explains their different properties why they have the color they do why they melt at the temperature that they melt at why they're as hard as they are and so on so the microstructure 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 organization they might be differently packed say but the corpuscular ian 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 Ian hypothesis so he's talking about the stuff of which things are made whatever that is on the corpuscular ian hypothesis it would be the universal matter from which the corpuscles are composed so this underlying substance is hypothesized to have primary qualities that is shapes 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 color 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 caused 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 ok quite familiar I bring my hand close to the hot plate and I feel warmth I'd bring it still closer and I feel pain well the sensations of felt warmth and pain are clearly in the mind we don't attribute the pain to the hot plate itself we're not even tempted to do that warmth may be less clear but at least the felt sensation of warmth we won't attribute that to it the circular shape where we are inclined to attribute that to the object the hot plate really is circular we think what about the red color 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 colored we're naturally too inclined to think of the color as they're in the object but if we start speculating about the mechanisms of perception as one naturally does 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 book 2 chapter 8 section 10 which is quite notorious Locke 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 ie by the bulk figure texture and motion of their insensible parts as colours sounds tastes etc these I call secondary qualities ok 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 are nothing in the object but powers they're nothing but powers they are in the object that they are powers now some people have interpreted a lot 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 object are powers now Berkeley red lock as denying that secondary qualities are in objects he thought lock was saying that secondary qualities are just in the mind not in objects but lock 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 Locke 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 Locke 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 color 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 intent 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 it's 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 in 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 and 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 object so when you read Locke and Berkeley on these things it's it's worth bearing in mind that Berkeley and indeed Hume get Locke wrong in this particular

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Length: 14min 32sec (872 seconds)

Published: Wed Apr 13 2011