so John Lock's distinction between primary and secondary qualities and his Arguments for the distinction and uh what he thinks the world is like so bit of background lck is an empiricist not a rationalist like dayart so uh the usual distinction between empiricist and rationalist back then is rationalists believe that we have innate ideas that is uh babies born fresh into this world have already got some ideas in their minds all sort of imprinted already in their minds they're hardwired as we would say now to already believe certain things and that's the basic building block block of everything that we know thereafter according to the rationalist so if from those ideas that you start out with you can logically deduce other ideas then you can you can expand your knowledge without ever having experiences whereas the empiricists of which Lo is uh the first no he's not the first hubs is uh before him but um Lo is uh definitely an empiricist the empiricists argue that babies are tabularasa that is they're born blank slates there are no ideas that you are born with any idea that you end up having you will have acquired uh will either be based on or will have been directly acquired through the census um so uh any even ideas of math you have to have had experiences of the world that will trigger these deductions that lead to ideas of math so the senses are very important now dayut rationalist uh goes to Great Lengths to argue that um the senses could be deceiving us uh that's the first meditation decart's first meditation he gives uh skeptical arguments why we can't trust the senses most famously obviously that we could be dreaming that is just as in our dreams we have ex we have sensory experiences we in our dreams we see things happen but then when we wake up we realize oh we were having this what it seemed like Sensations to us it seemed like we were seeing things but in fact there were Sensations with nothing really causing them we just had the sensations without there being anything real to cause them the sensations just were figments of our imagination were caused in some way by our own minds um because we know that that's possible then it's possible that when we have Sensations and we think we're awake those Sensations are not caused by what we think they're caused by you know a real thing uh my sensation of I think that I'm wearing a shirt because I can see it and touch it uh but maybe that I'm just having Sensations as if I'm wearing a shirt but there's no real shirt there uh the the modern way of putting this is we could be brains in Vats with little electrodes attached to them being fed uh electrical imp pulses that trigger the parts of the brain that are do to do with the senses uh so I feel like I'm like tasting an apple when in fact I'm just a brain and a vat and I don't even have a body and there's no apple there in other words there's this gap between ideas in our minds and what we think are caused by it and all we've got to go on are the ideas in our minds so we can't know that what that there is anything out there causing them or that um that there's a real world at all now dayart uh isn't a skeptic he doesn't he he doesn't end up thinking that yeah we can't trust our our senses but his reason for undermining the skepticism is a rationalist one he thinks that there are uh there there are ideas that cannot be doubted and that from them just by thinking rationally you can reconstruct uh and you can come up with a reason for why we could trust us senses very quickly he thinks that you can uh there is something you can never doubt that you exist this is his famous I think therefore I am um you cannot doubt that you exist because you know either you're right that you exist or if you're doubting that you exist you still have to exist to en able to in order to doubt so there is uh at least one belief that you can be sure about and then rationally using logic you can move through several steps until you can prove the existence of God and you can prove the existence of a perfect God who would not deceive you about what your senses are telling you therefore you can trust your senses but this is a rationalist approach to it a an empiricist like uh like Lo basically he says no you your brain would be still be empty if it weren't for the senses so there's nothing to go on um prior to the senses that can justify the senses so in some sense we have to have a reason to believe what our senses are telling us otherwise his whole empiricist program kind of collapses um now uh he does have a few arguments that are included in the reading I've given about why how you can tell the difference between dreams and reality for example at one point he says um sense one of the things that's special about Sensations is you can tell that they're really being caused by something out there in the world because they back each other up if we were just imagining if our senses were just imagining then there would be no reason for our senses to coincide I could just have visual Sensations and I could have auditory Sensations and they wouldn't appear to be of the same thing it would just be as if you had a a film strip going and then a totally different soundtrack Going because why would they be related if you're just imagining them but what actually happens with our Sensations is if you see something uh and you're not sure it's really there you know it's really there if you can touch it so in other words my my two senses that are otherwise unrelated touch and sight appear to uh back each other up and support the idea that there's something really there so the simplest explanation of this coincidence between s sight and touch is that there's an actual thing out there that's causing both my sensations of sight and touch it's a single thing explaining both phenomena uh so that's one explanation for why uh you can believe that there's something out there now having said that uh what is the world actually like if you're an empiricist you have to use your senses to get at what the world is actually like so it's kind of surprising that Lo ends up arguing that the world the the material world uh is not as it appears to us um so let's look at his view first of all uh he divides he he distinguishes between qualities which are features of the material world if there were no Minds in the universe there would still be qualities if all humans and any thinking and perceiving creature were wiped out from the universe or before any uh humans or perceiving creatures developed evolved in the universe there already were qualities they're just features of matter what is matter well matter is qualities that are somehow held together and supported by something he calls uh sub material substance literally the word sub the prefix sub means under it's as if it's like the dough that holds the raisins of qualities um together now what's slightly embarrassing for lock the empiricist is substance is completely imperceptible the only reason he believes that substance exist is because uh he infers to the best explanation the best explanation of how certain qualities stick together like for example in an apple you've got the quality of red or green combined with the quality of the taste combined with the sound that it makes when you bite into it all of those qualities are quality qualities of a single thing and the qualities are clustered together because they're all embedded in something called substance but by definition you can only perceive the qualities you cannot believe perceive the substance so it's a bit like what uh his idea of substance should kind of remind you if you're familiar with ideas from contemporary physics the idea of Dark Matter supposedly like 90% of the universe is composed of something called dark matter which we cannot detect we just know that it must be there because otherwise the math doesn't work otherwise there's far too little matter in the universe to explain what's going on so physicists say there has to be this thing called dark matter that we can't detect but it has to be there because otherwise our theories break down lock has a similar argument for this thing called substance but the things that the features of substance that we can actually perceive are the qual qualities and they can div be divided into three kinds there's primary and then there's what he calls uh secondary and he calls at uh most of the way through the reading bare Powers but then in the end when he summarizes he lumps the secondary and the bare Powers both under the title secondary and he calls what he has been calling secondary qualities secondary qualities immediately perceiv that means directly perceptible and then the bear powers are secondary qualities immediately perceived that is you can't perceive them directly you can just perceive that something has them because of its effect on a third thing for so a clear an obvious example of this is magnetism if a if you look at a magnet you can't see the magnetism but you can perceive that it is a magnet by its effect on iron filings or something iron that you can see that it is a magnet once you put a piece of iron near it and you say oh okay I can see that that's magnetic but you can't directly see the magnetism so it's immediately perceived you perceived that it has it because of this uh effect that it has both of these things should be lumped together though because they are both powers of the primary qualities in a way that I'll explain in a second okay so this is what uh what's happening in the material world and then this in the thought bubble here is your mind now you have ideas of that you think represent the primary qualities so the primary qualities of an object uh say for example this um well is it a pen is it a marker it's it's actually chalk so I'm going to call it a pen I was just mocked by some of my high school students who said that this is not a pen it's a marker a pen a marker is a pen I mean anyway I'm not going to have that argument again I'm going to call this a pen it has certain qualities that is it is a certain length it is a certain width it is solid if you sque if I squeeze it my fingers don't go through it I can detect the solidity so these solidity is one of them extension just means you know its dimensions in three space height width and so on figure means the shape and Mobility is whether or not it moves that all of these things are primary qualities of an object now I perceive this pen as having a certain shape and as having a certain width and height and so on so I have ideas that I think resemble the features of the pen uh my mental picture all I have to go on is a mental picture but according to lock that mental picture of the pen at least in respect of the the these primary qualities resembles the real thing so there is a real pen out here causing my perceptions of it that has the height and the width and the shape that I think it does so my ideas of the primary qualities resemble the qualities themselves but notice that's not the only properties that this has uh this is green this is black so it has color I'm not going to taste it but it can smells a bit chemically uh makes a sound when I flick it and it it feels smooth um or it it feels uh it feels a certain way in terms of its um uh temperature so those are other qualities that uh I think this has so I have exactly the same reason for thinking that this pen is green as I have for thinking that it is this height but here's the deal lck says although I'm right about these qualities I'm wrong about these that is I the only green that exists is in my mental picture of this pen there is no green in the pen itself all that and in fact all there really is is the primary qualities these are the only things that are really in the material world the material world consists of these things so then the question is well but why am I seeing color why am I tasting taste and the answer is so how how are my ideas of these things the secondary qualities caused and if you look in section 12 of the reading he he gives an answer and it's sometimes called the causal theory of perception essentially um the so notice that uh here I've got an arrow going directly from the qualities to the ideas because the primary qualities directly cause our ideas of them but we think that the secondary that there's there really is color in the world and it's directly causing our idea of color but in fact what's causing our idea of color is some actual feature of the primary qualities how is my idea of green being caused by some combination of these the his answer is things that have a certain shape and solidity are but that are imperceptible they're too small for me to see are flying off the real pen flying at my eyeball bouncing off my eyeball causing little ripples to go from my eyeball through the um the nerves in my you know the optic nerve that leads to the brain to the brain and then to my mind remember my mind and my brain are not the same thing a brain is a physical object your mind is what you think with this is one of the puzzles of philosophy how are the mind and brain related but anyway um so my idea of green is caused by tiny little you know atoms or molecules uh that fly off this thing and and that's how actually I'm able to see things at a distance because Lo doesn't actually have a theory of light light uh that was only really understood after Lock's time so Lock's view of the material world is as entirely governed by Newton's Laws Newton's Laws of Motion Lo is a huge Newton fan Lo basically begins his great work the essay by saying I'm not a you know I'm I'm sort of in the shadow of this awesome genius uh Newton and my job is just to sort of clear away uh misunderstandings that are stopping people from understanding the greatness of Newton Newton got everything right according to lock Newton uh Newton's Laws of Motion describ how everything works so the entire universe is just made of bodies that have this feature these features so they're solid they're extended they have shape and they move so any phenomena that we think are out there in the world are some combination of this what is color color is just an effect of certain kinds of molecules hitting our eyeballs maybe different shaped molecules cause green or red or whatever but there's no actual green there's just molecules of a certain shape flying off this now once we understand light lock is basically right about color because what we think color is now is we think this is green because it reflects light of the wavelength green it absorbs light of all wavelengths except green wavelengths and why does it do that because of its surface texture in other words something that can be explained in terms of its figure so actually this pen is green in the sense that it has a certain surface texture that reflects light but there's no greenness in it the greenness is just a byproduct of when you shine light on it something reflects off it there's no actual green here uh so modern science kind of backs lock up in this respect so the real world so notice again what's kind of weird about what Fox's doing he's saying our ideas are are are we're right that there is a real world out there and we know there's a real world out there because of Sensations but the real world is not as we sense it it's different so how on Earth can you can your senses tell you that the world is not as your senses tell you it is the answer is well if you think about it and you do a bunch of little experiments lock is a good empiricist in that most of his examples sound like tiny little science experiments so for example here are some features of the primary qualities primary qualities are inseparable from matter that is you can cut up uh or or try and alter a chunk of matter any way you like and it will never lose these features because that's what a chunk of matter is it's these primary qualities so he says in section n he says take a grain of wheat divide it as much as you like it will still have these features but if you really pound it it will totally change in all the secondary qualities you can in some sense remove the secondary qualities later on he gives an example of pounding an almond an Armond starts with a certain color and taste you can change the taste of an Armond just by pounding it so that must mean The Taste is not built into it so the secondary qualities are separable and remember His argument uh about how we can tell Sensations are real because they're accessible to more than one sense well that's true of primary qualities primary qualities are accessible to more than one sense now this kind of only works with touch and sight though um um but nonetheless it's certainly true that you can tell solidity by sight because you can tell something solid when you can't see through it but also by touch you can tell the shape of something by sight and by feel figure you can tell something is moving by you know uh you can touch it and feel that it's moving and also see it so all of these are accessible to only one sense whereas all of these are just one sense this is sight this is taste smell and so on um so those are features because we can work out these features uh if we use if we think carefully about it we can work out that these are two separate kinds of things and furthermore we can work out that if we believed that these these qualities were actually in in something we would be led to paradoxes so for example um this is one of my favorite examples the water tub in section 21 you've probably done this where you have three tubs uh this is a good you know Elementary School science experiment you have three tubs uh cold hot and lukewarm you stick a hand in the cold or stick a hand in the hot you wait for a little bit as long as you can stand and then you put them both in the lukewarm water now the uh hand that was in the hot tub feels the lukewarm water now as cold the hand that was in the cold tub feels the lukewarm water now as hot so how do you know what temperature water is the answer is by touch but now your touch you two different things your touch this hand is telling you that it's hot because it's just come from the cold water this hand is telling you that it's cold well which is it is it hot or cold and his answer is that it's neither because there is know warmth is a secondary quality that is not really in it so why are we getting these idea where are we getting these ideas of warmth and here the answer is in terms of mobility of the particles of the um of the water so uh he actually gives the correct explanation which is uh heat where in the old days they used to think that heat was a real kind of sort of power of something that there really was this thing hotness and this thing called coldness and we could feel them but he says no there's no heat there's no cold there's just Mobility so what we call hot is just uh stuff that where the particles of it are vibrating really fast so when you heat something you're just making the particles in it move faster so heat is actually just motion which is a primary quality and the reason why it feels cold to the hand that's just been in the hot water is because the hot water has made all the molecules uh move fast in your hand and now when you're move putting them into something colder than that they're slowing down and the deceleration of the uh the molecules in your hand causes it to feel cold so the water is neither hot nor cold there is no such thing as heat out in the world all there is is this stuff um and there's a couple of other examples uh when you read Lo for any amount of time you'll see a lot of his examples involve pain I don't know if he's a sadist or a masochist or whatever um but well it's probably because pain is a really it's a really nice example of a sensation but it's also a sensation that we don't think represents anything so the example of the fire in section 16 is a great example on he says okay you think that warmth is in the fire your your common sense view is that the fire has this stuff called warmth in it uh and why do you think that because it feels warm to you he says but here here's the thing you think that the fire is warm because it feels warm to you stick your hand in the fire there there's at least three or four cases where he says stick your hand in something hot clearly he hates his readers and he wants them to s suffer but uh stick your hand in the fire and you feel pain do you think that there's pain in the fire and that your feeling of pain is caused by uh the fire transferring the pain that is in it into your hat of course you don't you understand that pain is just something that happens in your mind it's not in the thing that causes it so you understand that the pain which is an idea anything that happens in your mind mind as an idea doesn't resemble the cause of the pain and he gives an example of a knife you know if you're stabbed with a knife you don't think that there's pain in the knife you don't think that your idea of pain that's undoubtedly caused by the knife you don't think it resembles something in the cause so ideas can be caused by things that don't resemble them and we know that with pain we just forgot that with warmth but we're right about pain and we should think exactly the same about about warmth that the cause of our sensation of warmth doesn't resemble it isn't anything like warmth in fact it's motion um now this is all setting up for Barkley to agree with some of the things that Lo says but uh turn some of his own arguments against him but uh basically so things to remember Lo does believe that there are primary qualities in in um an object but he also believes that there are secondary qualities it's easy to to speak sloly and say that Lo doesn't believe that there are secondary qualities now if you list color as a secondary quality it's true he doesn't think that is in an object however he does think that there's something really in an object that causes our idea of it it just doesn't resemble the idea and in fact what secondary qualities are are powers of primary qualities but they really are powers that primary qualities actually have so for example taste when you you taste something that's caused by some combination of these reacting with uh the structure of your tongue and causing uh sensation in your mind but orange juice doesn't taste sweet anymore than it tastes whatever disgusting taste that is that when you drink it just after you've brushed your teeth that's horrible if you haven't brushed your teeth it tastes good but in fact neither of those tastes are actually in the orange juice orange juice doesn't really have a taste it just has some combination of these that causes us to taste it a certain way if we were designed differently we would taste it completely differently um so that I think is enough for um for lock at the moment there you go that's locks I IDE distinction between qualities and ideas and ideas and the causes of those ideas