Primary and Secondary Qualities

i'm going to talk about an important distinction not only in early modern philosophy but in philosophy in general it's the distinction between primary and secondary qualities john locke introduces that terminology and talks about this explicitly and gives us the classic characterization of what these qualities are but this distinction is already there in earlier philosophers like descartes or gesendi and so it's something that locke is already picking up at least the general idea from other people and then developing it and making it a key part of his own philosophy they don't really give it names like this but locke does and builds it into the structure in an important way it also becomes a target for later figures in the empiricist tradition like barkley and hume who reject this distinction and think that locke is partly drawing a distinction where there isn't one but also drawing the wrong conclusions from it so let's take a look at first before we think about this particular distinction something that i think gives rise to the distinction and the similar thinking let's go back to ancient times and in particular the skeptics like philo of alexandria or sextus empiricus who talk about the argument from comparison the argument from comparison says that we never really encounter objects in the world as things in themselves they always come filtered through our own cognitive and perceptual apparatus we always know things not in themselves but in relation to other things and in particular in relation to us the faculty i have a vision for example affects the way i see things and then my brain processes all of that and the brain is processing it in a way that affects it as well so the image i end up with in my eye and then in my brain in my mind that may be quite far removed from what the object itself is so we know things only as they relate to us we can't distinguish what's really in the object from what we are contributing and our own faculties are contributing a nice way of looking at this is to consider a case like this which was popular on the internet a few years ago this particular dress that is one dress but in different lighting it looks very different in one context it looks blue and black in the other it looks white and gold and the question was what color is the dress all sorts of people fought about it they said well it's obviously black and blue someone else would say no it's obviously white and gold and it turns out what is in the background and the general lighting of the dress makes a huge difference the little strip of fabric in between there linking them is meant to show that it is the same it is exactly the same dress it is exactly the same fabric and so the difference there is not in the object but look at the what version on the left look at the version on the right they look completely different and why because the background is a different color because the lighting is different and so it turns out that this difference is due entirely to our own perceptual apparatus our own cognitive apparatus it has nothing to do with the dress that is presumably not changing in color at all well that's a great case for the argument from comparison and people have found that color perception is like this in general move a color to a different setting a different context put it around different things and it looks very different to us psychologists have wanted to know well what does a color look like and how good are we at distinguishing colors if there is no context if you just see nothing but that color and the answer is surprisingly is we're terrible at distinguishing them we can't do a good job of distinguishing them at all and so show me something often the way they do this is by showing me a color through a tube so that all you see is that color patch you see nothing around it and you can't tell what it is that's an amazing fact about it but notice it may be that the patch down there is really very clearly brown or very clearly blue or orange or yellow and the fact that you're seeing only that suddenly makes you almost unable to discern what color it actually is the argument from comparisons as well exactly we never perceive things as they are in themselves we're always perceiving them through the filter of our own cognition well here's how sextus puts the point in the mode deriving from the relativity as we said above the existing object appears to be such and such relative to the subject judging and the things observed together with it but we suspend judgment on what it's like in its nature so how we see things depends on the context in which we see them and it depends on us not just on the object that makes it really difficult to tell what the qualities that we're perceiving are really in the object and which of those qualities are really in us the blue the black the white and the gold they're all in a sense relative to us and relative to that context they're not in the dress itself so he says we really cannot tell what's in the object and what we're contributing the knowledge of the external underlying objects is impossible we can't tell what their true nature is what the things in themselves are like at best we can suspend judgment and say i here's how it looks to me but i don't know whether the object is really this way the dress in this context looks blue and black is it really blue and black i have no idea i suspend judgment this problem becomes much worse with the atomic theory of matter the atomic theory poses a challenge to theories like aristotle's of substances or objects the atomic theory after all tells us things are composed of atoms the properties of those things depend on the nature and motion of atoms so that implies that things are not at all as they appear but that's a disturbing idea things don't necessarily have the qualities they appear to have at all take a look for example at this sheet of paper it's yellow right well yes and if you looked at it through a tube maybe you'd have a hard time discerning that it's tempting to walk it over to the camera and so you can see nothing but the yellow i'm pretty sure in this context though you're there's going to be enough around your visual field you'll have no problem discerning it as yellow but is the yellow really in the paper or is the yellow contributed by your visual experience well sextus would have said there's no way to tell we have to suspend judgment however after the atomic theory we're inclined to see it different we say hold on a second i now conceive of the object and its properties rather differently i think this is really not just one substance this is something that is some combination of atoms of molecules in a certain kind of structure and that structure is what enables me to see it as yellow but of course in different lighting i would see it differently bring in a black light into the room or a yellow light and it's going to look quite different and so i realized hm yes the context matters but a cat will see it differently a dog will see it differently other animals will perceive it differently here i've got a version of the argument of variability going but all that's a way of indicating that really according to the atomic theory this thing doesn't have any color at all it's a question of what wavelengths of light are being reflected by the sheet of paper and then how my visual system processes that and what kind of impression is created from that different animals will have different visual systems different people may divide up the colors a little differently perceiving them slightly differently and so when we think about that we realize wait there's a sense in which this paper has no color at all that's really not in the thing itself we're inclined to think now sextus says we can't judge but physics tells us man well maybe we can judge if this is really a function of the wavelengths of light and the way it affects my eyes and the cones in my eye and the signals that are then transmitted into my brain then i'm contributing the yellow it's not really there in the paper itself now something's there there is some configuration of atoms and molecules that enables it to reflect wavelengths of light of that kind in that range and so affect me in that way nevertheless it is the pattern of the molecules here that structure is there the molecules are there but on the other hand the yellow isn't there nothing really out there is colored color is a matter of how things affect our visual system well if that's the right way to look at things we realize hmm actually maybe the atomic theory tells us we can make some judgments about what's in the object and what we're contributing but it's going to imply that a lot of what we see not just color but maybe many other things and lots of what we hear lots of what we smell and so on those are really contributed by us they're not in the things themselves so that's a disturbing idea when we look at a classic picture of philosophy of mind something like this where i have a thought that that object is a triangle and the triangle is causing me to have that thought because i'm perceiving it and the word triangle or the the idea that gets mobilized in my mind of triangle it means or connotes something like a form or an essence triangularity and that does apply to that object the triangle so we can say that my thought or my language refers to or denotes that triangle that object in the world because its meaning connects up to that essence that the thing really does have really does exhibit and that's a nice little picture it's a picture you find in aristotle in aquinas in peter of spain and a variety of other people it applies to all categoric terms that is to say things that actually do refer to things in the world things that aren't just conjunctions or connectives or the word the or a preposition like in or other things that play a different linguistic function but after the atomic theory we're inclined to say wait that picture is not well really accurate it's a bit oversimplified why well in aristotle's view and in the view of aquinas and peter of spain and the entire ancient and medieval tradition objects cause perceptions and they're represented in those perceptions the paper is the cause of my perception of the paper and it's represented in my perception and the same thing is true of that triangle i perceive the triangle it is the cause of my perception and it is the content of my perception it is represented in my perceptual state so the causes of perception are equal to the objects of perception the things represented in the perception but according to the atomic theory that's not quite right the causes of the atoms the causes of the micro particles or the electromagnetic fields or whatever it is that is causing my perception maybe it's the sound waves maybe it's something else but whatever it is it is something like that that is causing my perception and the perception then represents something that actually has very little relation to the causes i don't see the atoms i don't see the molecular structure i pick up the paper it looks smooth it looks yellow i don't perceive any atoms i don't receive any molecules i can't tell any internal structure and when i look at it more carefully it doesn't help it still looks smooth and yellow it doesn't look like aha now i see the atoms so wait a minute it looks like the cause of my perception and then what's represented in my perception are two very different things well that would lead us to go back to that diagram and say hold on a second there is something in the world the atoms that make up that triangle or the light waves or the sound waves or whatever it is that our thought is directed about that is causing us to have the thought but then what gets represented in the thought and any essence that we connote by it what's the relationship between that and the atoms what's the relationship between the yellow and the atoms or the smooth and the atoms or the triangle and the atoms that's why i've got that marked as a question mark now it's not obvious and so is much of what we say about the world wrong are we thinking things have all these qualities like being smooth and being yellow and being a triangle that they don't really have well that's a frightening and ultimately skeptical thought so here's the way arthur eddington famous 20th century physics physicist put the problem in the world of physics we watch a shadow graph performance of the drama familiar life the shadow of my elbow rests on the shadow table as the shadow ink flows over the shadow paper it's all symbolic and as a symbol the physicist leaves it the frank realization that physical science is concerned with the world of shadows is one of the most significant of recent advances a world of shadows what is eddington talking about he gives us a famous example the two tables here i see a table for example it's a table as i ordinarily perceive it it's smooth it appears looks like it's made of wood it is firm it resists things i can put things on it it seems to be solid and so in general i attribute the things to it that i attribute to a table it has kind of blonde wood maybe oak um i say all those things about the table they seem perfectly fine but then i asked the physicist to tell me okay you analyze the table tell me about the physics of the table well now this is the second table in some way a shadow of the first or maybe the shadowing goes the other way it depends on our view of this but in any case the physicists will say well i see an object that consists of atoms in the following kind of structure and i see them arranged in this pattern and reflecting light of these wavelengths and i see a complex pattern of striations in this wood that's actually a complex of organic compounds of the following structure and in short the scientist is going to describe the table in ways that are very different from the ways we would describe it now sometimes it's just different but sometimes it seems to conflict i say well the table is solid right the physicist says well actually much of it is really empty space it is simply all these particles that are vibrating very rapidly and in rapid motion and they move rapidly enough that they do resist pressure so i'm not saying it's not it doesn't feel solid of course it does but actually the percentage of that volume that is taken up by the actual particles is relatively low and bubble so wait it's not solid it's mostly empty space it seems to be stationary but in fact things in the in rapid motion it seems to have a color but in fact it has no color wow that physicist image of the table is really different from our ordinary image of the table what's represented in my consciousness is that ordinary table but lurking behind it in some way is that physical table that's actually the cause of my perception of the table even though it isn't at all like what is represented in my perception of the table well here's how we might put it then the causes of perception are the atoms the atomic structure the waves the things that are really there according to the physics but we don't see any of those things we just see their effects what we see therefore doesn't really exist in reality something does the atoms do let's say according to the physical theory of atomic theory uh saying the world consists of these atoms molecules and so on but it creates a problem how can we distinguish the aspects of the effects the appearances that is to say the perceptions that do match these causes i look at things and i think well are those things parts of the world are they being contributed by my mind are these qualities they seem to have things that are really there in the object are they being contributed by my mind is the paper really yellow or is that just a mental construct and the paper really is colorless the table is it really mostly empty space or is it solid how do i tell what's really in the object itself now lock is going to say let's distinguish two kinds of qualities the qualities that are really possessed by the collection of atoms call those the primary qualities they're really there in the world they're part of the thing but qualities of the appearance only that are being contributed by the mind call those secondary qualities you might see philo and sextus as already having given you the grounds for distinguishing primary qualities from secondary qualities some of these things are really there in the things themselves some of them are being contributed by our own perceptual and cognitive faculties but which are which phylo and sexistus would say i have no way of knowing however lock says maybe i do and here's my way of knowing physics i study the underlying science i study my perceptual apparatus i do both physics and cognitive science to find out what really is going on in the world and a formulated theory then about how my mind and my brain are processing this and why i have the right representations that i do so here is how lock defines primary qualities qualities thus considered in bodies are first such as are utterly inseparable from the body in what state so ever it be and such as in all the alterations and changes it suffers all the force can be used upon it it constantly keeps and such a sense constantly finds in every particle of matter which has bulk enough to be perceived and the mind finds inseparable from every particle of matter though less than to make itself singly be perceived by our senses so in short he gives us two criteria two closely related criteria for a primary quality they are inseparable from the object and they are constant they are things that are there in the object in every part of the object so here's an example take a grain of wheat divide it into two parts each part still has solidity extension figure and mobility divide it again and it retains still the same qualities so divide it on until the parts become insensible they must retain still each of them all of those qualities these i call original or primary qualities of body which i think we may observe to produce simple ideas in us solidity extension figure motion or rest and number that's an interesting example i have a friend who was a very fine musician but gave up music to become a miller and now he mills grain not too far from austin he takes grains of wheat and rye and other things and breaks them down in this way now as he does this many of the qualities change something will go from having a bitter taste for example to having a sort of sweet taste something will go from appearing golden to appearing white something will go from appearing dark blue to appearing well a very slightly bluish white and so forth all of those things change about the appearance but there are some things that do not change solidity for example it still has a kind of solidity even in the tiny parts take some flour and put it between your hands it's not going to resist in the way that a wheat berry does but still it will resist to some degree it still has extension it still takes up space it still has some mass it still has some shape it's got well we can talk about it moving or remaining still and so all of those things are properties that the flower still has that were there in the berries of wheat however a lot of other properties change so the ones that are remaining there are the primary qualities they are still there now notice the particles of flower are much much smaller than the particles of wheat that we start out with they've been broken up and broken up again and again however even though the size changes it still has size even though it still has some mass that may be changing it still has some mass and so it still has properties of that general kind those are its primary qualities so here's how descartes tends to think of it the primary qualities are something like the mathematical properties they're assigned to atoms by physical theory so they're things like size shape mass motion if we look to physics look to a theory like that momentum is mass times velocity force is the derivative of momentum the force in one direction is always met by an equal and opposite force those are basic newtonian laws of motion and what are we talking about there we're talking about basic physical properties so mass velocity momentum force direction those are things we can talk about as primary qualities so they are in short inseparable from the objects even the atoms have them they are things that the objects possess according to the atomic theory of matter locke says they produce simple ideas in us and those simple ideas represent the primary qualities in the objects exactly so which of the qualities in our perceptions can we trust to be really there in the objects themselves things like that the primary qualities things like solidity extension mass motion so those are things descartes says we clearly and distinctly perceive we can trust that they are in the objects themselves and they and only they reflect the true natures of things secondary qualities on the other hand are different they are the effects of the primary qualities on us examples color texture maybe moral and aesthetic qualities they are separable they are variable so the yellow of the paper that's a secondary quality that is a quality that is being contributed by our own perceptual faculties it's not there in the paper itself the paper itself is colorless according to the atomic theory but it's something nevertheless that we perceive it is being contributed by us it's not in the thing the same thing is true of the texture it feels smooth to me well if i go down to the atomic level it doesn't look very smooth but that texture is something being contributed by my own cognitive faculties i'm not very aware of the fine details of that luckily or the world would seem to be an incredibly bumpy place it would be very uncomfortable so in short we are going to perceive the world in a way that is going to consist of a combination of primary and secondary qualities the primary ones are really in the object the secondary ones are not they're being contributed by our own cognitive faculties they're a matter of how those primary qualities there in the world are affecting us so locke gives the definition of a secondary quality this way secondly such qualities which in truth are nothing in the objects themselves but power to produce various sensations in us by their primary qualities that is by the bulk figure texture and motion of their insensible parts as colors sounds tastes and so on these i call secondary qualities so there are the effects on sensation of the primary qualities of objects they are the power of those objects to affect us they depend on the primary qualities but they are separable and they are variable i pound that weak berry into flour and the secondary properties often change so yeah color changes as i pound this and grind it into flour the texture changes the taste may change all of that can change however the primary qualities are still there it still has solidity extension weight it still either moves or remains stationary and so on those primary qualities are had by the flower as well as by the original berries well then here's the idea overall we look at the world and we say what is really in the world and what's being contributed by us sexist philosophy no way to tell suspend judgment lock says there is a way to tell it's natural science look at our scientific theory of the world the ideas of the primary qualities of bodies are resemblances of them their patterns really do exist in the bodies themselves the ideas produced in us by these secondary qualities have no resemblance of them at all there's nothing like our ideas existing in the bodies themselves there's nothing like color that's really in the paper we don't look at the atoms we don't look at the electrons and say well it's made up of yellow electrons at one point my father told me chocolate milk came from brown cows well you might think oh yellow paper is made of yellow molecules no it's not that's not how it goes at all the molecules have no color and so this is the color is something being contributed by us that's an important fact to know and lock says we don't have to face the world saying just we we are always perceiving things in relation to other things and in relation to ourselves so we can't tell he says physics tells us we do have theories of the world and we have theories of our own cognitive capacities as well we do have cognitive science cognitive psychology that allows us to study our own perceptual faculties and our own cognitive faculties so we can come to some conclusions about what's really in the world those are the objects that physics postulates lock is a scientific realist he says the things that are really in the world are the objects that science postulates as being the fundamental entities in the world the things that are other than that are the things that we are contributing secondary qualities in particular like color are just the effects of objects on our nervous systems or if we want to talk about them as really being in the object they're the powers in the object to affect our nervous systems in that way they produce ideas in us that do not resemble the object they are effects that have nothing corresponding to them in the object so they do depend on the primary qualities it's because of the primary quality of the paper that i'm actually able to perceive as yellow but the yellow isn't itself a primary quality it's not itself in the paper these secondary qualities are what contemporary philosophers refer to as response dependent to have one is just to produce a certain kind of effect in a normal perceiver so we could say for example that something is red if it just affects a standard perceiver in standard conditions in a certain kind of way well that allows us to say the realist and the idealist are both in a sense right the realist says in general some things are mind independent the idealist says no everything is mind dependent locke and descartes say well let's be a little more specific some things truly are mind independent they're both realists in those those terms but we can talk about realism about specific things you might be a realist for example about the existence of scientific objects and an idealist about moral properties or about other kinds of things so let's say that a realist about some subject x says that some of these x's are mind-independent an idealist about that thing is going to say all of those things are mind-dependent and now we can articulate this we can say just as to be read is just to look red to a standard perceiver in standard conditions so we want to be realists about the primary qualities but idealists about the secondary qualities that is to say we want to say extension motion mass figure those are really in the object we're realists about those qualities but on the other hand colors textures tastes we're idealists about those they're contributed by the mind so descartes and lock are realists about the primary qualities those things are mind independent they exist in the things themselves and our ideas of them are adequate they match what's going on in the world but they're idealists about the secondary qualities the secondary qualities are mind-dependent they don't exist in the things themselves they're contributed by the mind alone the color is the result of my perception of the paper it's not there in the paper itself our ideas of these secondary qualities are inadequate they represent the object not as it is but actually in a way that's divergent and in some cases outright conflicting from the way it is so we look at something like the fabric of the dress sometimes it looks white and gold to us sometimes it looks black and blue or here we don't quite get to the black and blue but you can see it trending in that direction if it continued the color is being contributed by us but the primary qualities the actual pattern there that remains the same throughout the primary qualities don't change but the secondary qualities do because they depend on us they depend on the context they depend on other things in a way that tells us they're not in the things themselves but the primary qualities they are they're really there in the world you

Channel: Daniel Bonevac

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Id: -VZuAxaLMMA

Length: 30min 18sec (1818 seconds)

Published: Mon Feb 22 2021